Office of Research and 

Development 

Washington, DC 20590 

DOT/FRA/ORD-07/17 May 2007 This document is available to the

U.S. public through the National

Technical Information Service

Springfield, VA 22161.

Federal Railroad

Administration

U.S. Department

of Transportation

In-Track Demonstration of Laser-Treated 

Rail to Reduce Friction and Wear 
Notice 

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the Department of Transportation in the interest of 

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assumes no liability for its contents or use thereof. 

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May 2007

4. TITLE AND SUBTITLE 

In-Track Demonstration of Laser-Treated Rail to Reduce Friction 

and Wear

5. FUNDING NUMBERS 

DTFR 53-00-C-00012 

6. AUTHOR(S) Task Order 226

Richard Reiff

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION 

Transportation Technology Center, Inc. REPORT NUMBERS

P.O. Box 11130 

Pueblo, CO 81001

9. SPONSORING/MONITORING AGENGY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY 

U.S. Department of Transportation REPORT NUMBER 

Federal Railroad Administration DOT/FRA/ORD-07/17 Office of Research and Development, MS 20 

1120 Vermont Avenue, NW 

Washington, DC 20590

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

This document is available through National Technical 

Information Service, Springfield, VA 22161.

13. ABSTRACT

In-track evaluations of a laser-treated rail intended to provide a permanent reduction of the friction level and 

increased wear life were conducted at the Transportation Technology Center’s Facility for Accelerated 

Service Testing, Heavy Axle Load track in Pueblo, CO. These evaluations were conducted during the 

October 2005 operating period. Results suggest that the cracks formed during the laser treatment process led 

to early spalling and chipping of the gage corner, requiring removal of the test rail from the track. Limited 

data suggests that the treatment process did not significantly reduce gage face rolling friction. 

15. NUMBER OF 

PAGES

67 

16. PRICE CODE

14. SUBJECT TERMS

Laser-glazed rail, laser-treated rail, spalling, and chipping

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF 

OF THIS PAGE OF ABSTRACT ABSTRACT 

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED 

NSN 7540-01-280-5500 Standard Form 298 (Rec. 2-89) 

Prescribed by ANSI/NISO Std. 

239.18 

298-102
ii
Table of Contents 

List of Figures...............................................................................................................................v 

List of Tables...............................................................................................................................vi 

Executive Summary......................................................................................................................1 

1.0 Introduction .........................................................................................................................3 

 1.1 Background.................................................................................................................3 

2.0 Objectives............................................................................................................................5 

3.0 General Project Approach ...................................................................................................7 

 3.1 Test Rail......................................................................................................................8 

 3.2 Inspection of Received Rail........................................................................................9 

 3.3 Measurements...........................................................................................................10 

4.0 Installation of Test Rail .....................................................................................................11 

5.0 Results ...............................................................................................................................13 

6.0 Laboratory Evaluation of Rail Samples ............................................................................23 

7.0 Conclusions and Observations ..........................................................................................25

8.0 Future Application and Development ...............................................................................29 

Appendix A. Laser-Glazed Rail Failure Analysis.....................................................................31 

Appendix B. Nuvonyx Laser-Glazing of Rail for AAR/TTCI FAST Loop Tests ....................57 

Acronyms ...................................................................................................................................67 

iii
iv
v

List of Figures 

Figure 1. FAST Loop and Location of Test Rail....................................................................7 

Figure 2. A Typical Rail Showing Dark Grease in Area that Should Have Reduced 

Friction ....................................................................................................................8 

Figure 3. Overall View of Laser-Treated Rail Before Installation.........................................9 

Figure 4. Closeup of Laser-Treated Rail Before Installation .................................................9 

Figure 5. Laser-Treated Test Rail as Installed in Section 07 at FAST, Before 

Train Operation ..................................................................................................... 11 

Figure 6. Control Rail After 1.2 MGT.................................................................................. 14 

Figure 7. View Along Gage Corner, Looking in the Clockwise Direction 

After 1.2 MGT....................................................................................................... 14 

Figure 8. Typical Chip Noted on Gage Corner of Laser-Treated Trail 

After 1.2 MGT....................................................................................................... 15 

Figure 9. Two Chips on Gage Corner of Laser-Treated After 1.2 MGT.............................. 15 

Figure 10. Closeup of the Same Location as Shown in Figure 9 After 1.2 MGT .................. 16 

Figure 11. Overall View of Thermite Weld in Laser-Treated Section After 1.2 MGT.......... 16 

Figure 12. Closeup View of Thermite Weld as Shown in Figure 11 in Laser-Treated 

Section After 1.2 MGT.......................................................................................... 17 

Figure 13. Summary of Tribometer/Friction Data Showing Only a Slight Reduction or No 

Change Between the Laser-Treated and Untreated Surfaces ................................ 18 

Figure 14. Control Rail Showing Rough Gage Face from Dry Operation. Shiny Gage 

Corner After 5.6 MGT .......................................................................................... 19 

Figure 15. Control Rail Closeup Showing Dry Surfaces. No Pitting or Spalling 

After 5.6 MGT....................................................................................................... 19 

Figure 16. Junction of Control Rail to Laser-Treated Rail..................................................... 20 

Figure 17. Laser-Treated Rail After 5.6 MGT Showing Two Spalls ..................................... 21 

Figure 18. Typical View of Gage Corner on Laser-Treated Rail. No Spalls ........................ 21 

Figure 19. Thermite Weld on Laser-Treated Rail Segment After 5.6 MGT .......................... 22 

Figure 20. Close View of Spalls At and Near Thermite Weld After 5.6 MGT...................... 22 

Figure 21. Overlay of Control (untreated) and Laser-Treated Rail ........................................ 26 
vi

List of Tables 

Table 1. Notes from Pre-Operation Data Collection ............................................................... 13 

Table 2. Summary of Hardness and Friction After 1.2 MGT of Traffic at FAST .................. 13 
1 

EXECUTIVE SUMMARY 

In-track evaluations of a laser-treated rail intended to provide a permanent reduction of the 

friction level and increased wear life were conducted at the Transportation Technology 

Center’s (TTC) Facility for Accelerated Service Testing (FAST), Heavy Axle Load (HAL) 

track in Pueblo, CO, during the October 2005 operating period. Results suggest that the cracks 

formed during the laser treatment process led to early spalling and chipping of the gage corner, 

requiring removal of the test rail from the track. Limited data suggests that the treatment 

process did not significantly reduce gage face rolling friction. 

The limited time in track and small (5.6 million gross tons (MGT)) exposure to traffic was 

insufficient to obtain accurate wear data; thus the effectiveness of this process to control rail 

wear was not evaluated. While measurements did show dramatic increases in hardness of the 

laser-treated areas (from 360 Bhn to over 650 Bhn), the depth and thickness of this hardened 

layer could not withstand continued rolling loads of passing wheels. 

Future development of the laser concept must consider the tendency for cracks to develop 

during the treatment process. Any future laser-treated rail being considered for installation into 

track must be inspected for cracks. Surface cracking can be easily identified using dye 

penetrant and magnetic particle inspections. As some of these cracks are very small and occur 

in the subsurface, however, a metallurgical evaluation of samples cut from production lasertreated segments should also be conducted. This is to ensure that no hidden defects could 

develop into larger cracks or spalls and chips. 
2 
3 

1.0 Introduction 

1.1 Background 

Railroads utilize a number of lubricant materials and application methods to reduce friction at 

the wheel/rail contact patch. Data has shown that by proper application of friction controlling 

materials, rail and wheel wear life can be extended, and energy needed to move a train can be 

reduced. This has generally been achieved by applying lubricants to the rail’s gage face. 

Lubricants have been applied by a number of methods (mobile-and wayside-based); however, 

due to the limited life of lubricants once applied to the rail, the application is for every train 

passing a given location (wayside-based system) or must be applied virtually along the entire 

route, usually with systems mounted on locomotives (mobile-based systems). For the purposes 

of this project, an alternative to using lubricants that generally reduce gage face friction to 

levels of 0.25 μ or less is being considered. Other types of friction control products, which are 

intended to be applied to the top of rail, are also in use but were not considered for this project. 

This project has evaluated a concept that treats the rail gage face and is intended to provide a 

permanent reduction of the friction level (generally less than 0.25 μ), thus eliminating the need 

for constant reapplication of lubricants. By laser treating the rail surface, a hard surface is 

created, which is intended to reduce wear and produce a reduced level of friction. While this 

process has been demonstrated in laboratory settings that simulate the wheel/rail contact 

conditions, a full-scale demonstration had not been previously conducted. The Federal 

Railroad Administration (FRA), working with the Department of Energy (DOE), funded the 

testing of laser-glazed rail at TTC’s FAST in Pueblo, CO, conducted during the October 2005 

operating period. 
4 
5 

2.0 Objectives 

The objectives of the laser-glazed rail evaluation were to determine the following: 

• Ability of laser treatment to reduce rail friction to 0.25 μ or less 

• Ability of the laser treatment to reduce rail wear rates compared to untreated rail 

• Long-term surface fatigue performance of the laser-treated surface 
6 
7 

3.0 General Project Approach 

Favorable review of laboratory test results on the laser-glazing treatment, conducted by the 

National Research Council of Canada, were provided to FRA and DOE to justify these fullscale tests. Results were encouraging, such that an in-track test was funded to determine 

performance of a laser-treated rail under full-scale loaded wheels. The test site selected was in 

a segment of Section 07 of the track at FAST (Figure 1). By using the high rail of this curve, 

which is a nonlubricated, 5-degree curve, the effectiveness of the laser treatment in reducing 

rail wear and friction could be assessed. The FAST/HAL program is used to evaluate track and 

mechanical components under a train consist with 315,000-pound cars that impose between 

100 and 125 MGT annually on the track structure. 

Figure 1. FAST Loop and Location of Test Rail 
8 

Normal FAST operations utilize a 4-locomtive/75 (+/-) loaded car train, operating at 40 mph 

over the 2.7-mile loop. Each loaded car weights approximately 315,000 pounds at the rail. 

During one 10-hour shift, up to 125 laps can be operated, applying over 1 MGT of traffic. For 

comparative purposes, a typical North American mainline freight line will be subjected to 60 to 

90 MGT per year. 

3.1 Test Rail 

The Transportation Technology Center, Inc. (TTCI) obtained two 40-foot sections of identical 

141 AB (International Steel Group–formerly Pennsylvania Steel Group, heat-treated head 

hardened (HH) rail) for this test at FAST. One section was kept as is and installed as a control. 

The other 40-foot section was cut in half and then welded back together to form a 40-foot 

section containing a thermite weld in the middle. This weld was installed to determine if the 

laser-treating process would treat the casting-like material of a thermite weld in the same 

fashion as it does the pearlitic structure of regular rail. Heat-treated rail was selected as almost 

all major railroads now utilize such rail in curves, as the heat treatment provides superior 

performance in wear and deformation. 

The 40-foot section containing a thermite weld was then shipped to Nuvonyx, near St. Louis, 

MO, for laser-glazing treatment. Appendix B includes a report of the treatment process. TTCI 

provided information to Nuvonyx as to the recommended area of treatment, the gage corner 

area (Figure 2). As this was new, unworn rail, most wheels will contact the rail in the gage 

corner area. 

Preferred Area of 

Friction Reduction 

Figure 2. A Typical Rail Showing Dark Grease in Area that Should Have Reduced 

Friction 
3.2 Inspection of Received Rail 

Before installation at FAST, the rail was inspected for any major cracking. Figures 3 and 4 

show the rail before installation and that the laser-treated surface had a rough appearance. 

9 

Figure 3. Overall View of Laser-Treated Rail Before Installation 

Figure 4. Closeup of Laser-Treated Rail Before Installation 
10 

3.3 Measurements 

Because laser glazing of rail is an experimental procedure and its effect on the performance of 

rail under actual operating conditions was uncertain, to ensure safety, the rail was inspected 

visually each day following train operations. To determine performance of the laser-treated 

rail, monitoring locations were established on the control and laser-treated rail. Data included 

MiniProfTM cross-sectional rail profiles, hardness, and rail friction. 

3.3.1 Profiles 

A MiniProfTM profile was measured at the beginning of the test and scheduled every 25 MGT 

after that. Three measurement sites were implemented on the nonglazed section and three on 

the glazed section. Figure 1 shows these in numbered sequence. Due to premature failure, 

end-of-test profiles were taken after 5.6 MGT. 

3.3.2 Rail Hardness 

An Equiotip® Brinell device was utilized to measure rail hardness at the same intervals as rail 

profile measurements. 

3.3.3 Rail Friction 

Rail friction was measured with a hand-held tribometer. Due to the need for a distance of 

25 to 30 feet for the tribometer to measure, only 1 or 2 friction readings could be taken on 

either section. 

3.3.4 Photo and Other Documentation 

Photos were taken to show surface conditions, along with notes and records of train operation 

and tonnage. 
11 

4.0 Installation of Test Rail 

After the rail was laser treated, a short section was cut and removed for possible future 

laboratory analysis. The remaining 39-foot section was then installed in track along with the 

control rail. The laser-treated rail and control rail were installed at the same time. Rail was 

then installed on the outside of Section 7 of the High Tonnage Loop (HTL) at FAST, a 

nonlubricated, 5-degree curve where rail wear tests are conducted (Figure 1). 

Figure 5 shows the condition of the rail as installed before any train operations. 

Figure 5. Laser-Treated Test Rail as Installed in Section 07 at FAST 

Before Train Operation 
12 
13 

5.0 Results 

Before operation, all sites were measured for profiles, hardness, and rail friction. As shown on 

Table 1, hardness data was potentially impacted due to mill scale present on running surfaces of 

the control rail. The tribometer data may also have been impacted due to mill scale on the nonlaser-treated surfaces. Table 1 shows the hardness of the laser-treated surface is much greater 

than the control rail that is untreated surface (approximately 670 bhn versus 340 bhn). 

Table 1. Notes from Pre-Operation Data Collection 

Laser-Glazed Rail Test

Date: 10/14/05 

MGT: 0 Mgt first test 

Tie Location MiniProfTM Equio-Tip Hardness Tribo-Reading

File Name Top Gage Face Top Corner Face 

07-567 14102005-0011 347 N/A

07-574 14102005-0021 353 N/A 0.38 0.34 0.25

07-581 14102005-0031 348 N/A

07-591 14102005-0041 340 680

07-595 14102005-0051 350 668 0.35 0.32 0.23

07-604 14102005-0061 354 653

The hardness was taken with de-carb on the running surface. 

The tribometer readings were taken with scale and rust on the rail.

After approximately 1.2 MGT of operation, the rail was re-inspected and hardness re-measured. 

Field inspection of the control and laser-treated rail indicated no issues with the control rail; 

however, the laser-treated rail exhibited several chips and spalls. Table 2 summarizes the 

results of friction and hardness measurements after one night of train operation. 

Table 2. Summary of Hardness and Friction After 1.2 MGT of Traffic at FAST 

Laser-Glazed Rail Test

Date: 10/17/05

MGT: 1 MGT test 

Tie Location MiniProfTM Equio-Tip Hardness Tribo-Reading

File Name Top Gage Face Top Corner Face 

07-567 None 353 N/A 

07-574 None 350 N/A 48 31 30

07-581 None 341 N/A 

 

07-591 None 360 658 

07-595 None 346 650 48 32 30

07-604 None 368 650 

The laser rail still rough. Tribo still has a hard time giving a correct reading. 

Figure 6 shows the control rail after 1.2 MGT of traffic. Figures 6 through 12 document the 

visual inspections conducted after 1.2 MGT of traffic. 
14 

Figure 6. Control Rail After 1.2 MGT. Compare with Figures 14 and 15, 

Same Location After 5.6 MGT 

Figures 7 through 12 show the laser-treated rail surface conditions after 1.2 MGT of traffic. In 

Figure 7, note the smoothed gage corner, where most of the wheel contact appears to have 

occurred as compared to Figures 3 and 4, which show the gage corner before operating any 

trains and show no wear on the rail. 

Figure 7. View Along Gage Corner, Looking in the Clockwise Direction 

After 1.2 MGT 
15 

Figure 8. Typical Chip Noted on Gage Corner of Laser-Treated Trail After 1.2 MGT 

Figure 9. Two Chips on Gage Corner of Laser-Treated Rail After 1.2 MGT 

Compare with Figure 17 at the Same Location After 5.6 MGT 
16 

Figure 10. Closeup of the Same Location as Shown in Figure 9 After 1.2 MGT. 

Compare with Figure 17 on the Same Location After 5.6 MGT to Show 

Growth in Size of Spalling

Figure 11. Overall View of Thermite Weld in Laser-Treated Section After 

1.2 MGT. Compare with Figure 19 at the Same Location After 5.6 MGT 
17 

Figure 12. Closeup View of Thermite Weld (as Shown in Figure 11) in Laser-Treated 

Section After 1.2 MGT. Compare with Figure 20 at the Same Location After 5.6 MGT 

Information regarding chipping was transmitted to the sponsors and developers of this concept. 

After the fourth night of operation (5.6 MGT), the laser-treated rail exhibited severe spalling 

(12 spalls noted in the 40-foot length); thus it was decided to remove the rail from track and 

conduct metallurgical evaluations of the laser-treated surfaces. Although the cracking was not 

a safety concern at the time, further cracking would have prevented adequate rail flaw detection 

and reduced system safety. 

During the initial 5.6 MGT, tribometer data indicated almost no significant difference between 

the laser-treated and untreated surfaces, as summarized in Figure 13. 
18 

0

0.2

0.4

0.6

10/20/2005 10/21/05 pre clean 10/21/05 post clean

control top

laser top

control gage face

laser gage face

Figure 13. Summary of Tribometer/Friction Data Showing Only a Slight Reduction 

or No Change Between the Laser-Treated and Untreated Surfaces 

Inspection of the control and laser-treated rails after 5.6 MGT of traffic showed the following 

surface conditions. 

Figures 14 and 15 show the condition of the control/untreated rail after 5.6 MGT. 
19 

Figure 14. Control Rail Showing Rough Gage Face from Dry Operation. 

Shiny Gage Corner After 5.6 MGT 

Figure 15. Control Rail Closeup Showing Dry Surfaces. 

No Pitting or Spalling After 5.6 MGT 
As a concern existed that the surface condition might develop fatigue failures early in the test, 

the laser-treated rail was initially bolted in place, with the intent to weld it at both ends to the 

adjacent rail if no problems occurred. Figure 16 shows the appearance of the mechanical joint 

at the junction between the control and laser-treated rails after 5.6 MGT. As seen, the left side 

(center rail) shows no cracking and a smooth surface. The treated rail, to the right of the joint, 

is rough and shows signs of cracking. 

20 

Figure 16. Junction of Control Rail to Laser-Treated Rail. 

Left Side is the Control Rail; Right Side is Laser-Treated Rail 

Figures 17 through 20 show various locations along the laser-treated rail after 5.6 MGT. 

Figure 18 shows the smooth gage corner from contact with wheels but with large valleys and 

rougher surface of laser-treated area. Figure 19 shows spalling at the center and each side of 

the thermite weld; compare with the same location shown in Figure 11 after 1.2 MGT. 
21 

Figure 17. Laser-Treated Rail After 5.6 MGT Showing Two Spalls. 

Compare with Same Location as Shown in Figures 9 and 10 After 1.2 MGT 

Figure 18. Typical View of Gage Corner on Laser-Treated Rail, No Spalls. 

Compare to Figures 3 and 4, Which Show the Gage Corner Before Train Operation 
22 

Figure 19. Thermite Weld on Laser-Treated Rail Segment After 5.6 MGT 

Figure 20. Close View of Spalls At and Near Thermite Weld After 5.6 MGT. 

Compare with Same Location as Shown in Figure 12 After 1.2 MGT 
23

6.0 Laboratory Evaluation of Rail Samples 

Due to the premature failure of the laser-treated rail surface, in the form of numerous spalls or 

cracks that would likely develop into spalls, the rail was removed from the track after 5.6 MGT 

of traffic. In order to better understand the failure mechanism, a series of laboratory tests was 

proposed and authorized in lieu of continuing the in-track tests. Appendices A and B include 

results of the laboratory testing. 

TTCI recommends that any future specimens of laser-glazed treated rails undergo a full 

metallurgical evaluation to determine their integrity before installation in track. No rail should 

be subjected to HAL traffic, either at FAST or revenue service, with evidence of cracks similar 

to the ones observed in these rail sections. 
24
25

7.0 Conclusions and Observations 

The rail was removed from track after 5.6 MGT due to numerous spalls that developed along the 

gage corner area of the laser-treated rail. No spalling or other surface damage was noted on the 

otherwise identical, untreated control rail. Spalling on the laser-treated rail appeared to grow or 

originate from cracks created during the treatment process. These cracks were located in the 

very hard laser-treated material on top of the softer parent metal. Similar hardness transitions 

occur at engine burns or where improper rail grinding has been conducted, creating small 

sections of martensite next to the parent metal. At such locations it is common to see chips or 

spalls break out from the running surface. With the laser-treated rails, however, the cracks were 

preexisting and led to rapid failure of the rail section. 

In the laser-treated rail, the potential for cracks to develop into spalls was not at isolated 

locations, but along the entire gage face of the rail. For this reason, the rail was removed after 

12 large spalls were noted within the 39-foot laser-treated rail length. Additional operation 

would have likely led to additional spalling and possible safety issues. 

One issue that may have accelerated the development of spalls and chipping is that the laser 

treatment appears to have very slightly altered the rail’s profile. Examination of Figure 21 shows 

an overlay between a new 141 AB rail and the laser-treated 141 AB rail sections. The profile of 

the glazed/treated rail has minor bumps that are higher than the original profile. These locations 

likely make more frequent contact with passing wheels and would create much higher contact 

stresses until they are worn down or away. During the brief 5.6 MGT of exposure to traffic, it 

appears that many of these bumps resulted in chips and spalls. 
26

Figure 21. Overlay of Control (untreated) and Laser-Treated Rail 

Potential 

High Contact 

Stress 

Glazed Rail 

Control Rail
27

The laser-treated rail, as received, had a very rough surface along the gage face/corner area. 

Based on laboratory analysis of a sample from the laser treated, unused section, cracks were 

present within this laser-treated surface. Most of the small cracks, which likely developed during 

the treatment process, would have eventually grown into large cracks and led to additional 

spalling and chipping of the rail surface. 

The relatively short time of testing did not allow the gage corner/gage face rail surface to become 

smooth; thus reliable tribometer readings could not be collected. The limited amount of 

tribometer data obtained shows little or no difference between the control and laser-treated rails, 

both on the gage face and the top running surface. This suggests that the harder material did not 

affect the tribometer wheel in the stick-slip mode in the same fashion as grease or oil. Although 

the laser-treated rail exhibited a smoothed, narrow band along the gage corner that was also 

smooth to the touch, this did not produce friction levels significantly lower than the adjacent 

control rail. A dry, unlubricated gage face sometimes produces metal flakes, which can interfere 

with accurate tribometer readings. These metal flakes act like ball bearings (due to the size 

factor) and can reduce the measured friction value. An attempt to clean the rail did not, however, 

result in any increase in readings. In fact, a reduction in friction readings from the tribometer 

was observed. The cleaning effort may have removed only the larger metal flakes, leaving the 

small ones in place, resulting in reduced friction values. Again, even after cleaning, the laser 

treated and control sections did not show any significant difference. 

As only 5.6 MGT of operations occurred, measured wear was within the (MiniProfTM) 

measurement system error. In some cases spalling occurred at the location where profiles were 

to be measured, which would have produced erroneous results. A much longer period (25 MGT 

or more) would be needed to determine if wear were significantly reduced over the laser-treated 

segment. With the frequency, depth, and size of spalls, the laser-treated rail gage face would 

have exhibited large amounts of wear at many locations. 
28
29

8.0 Future Application and Development 

Based on the rough surface condition and the cracks developed during the treatment process, 

additional refinement of the laser treatment technique is needed to make this concept acceptable 

for general use in the freight railroad industry. Even small cracks, if not worn away, will grow 

with applied tonnage and eventually result in spalls or, in the worst case, cracks that turn 

downward into the rail resulting in breaks. In addition, the rough surface of the gage face makes 

normal ultrasonic inspection of this surface in the field virtually impossible. Thus inspection for 

cracks is difficult using routinely utilized inspection equipment. The rough surface is not a rail 

condition that most railroad personnel will be expecting; thus issues with cracks and inspection 

must be addressed for this process to be acceptable. Finally, the roughened surface also 

produced some minor bumps and variations that extend outward from the original profile. These 

bumps appeared to take the brunt of passing wheel loads and were likely the origin of some of 

the early spalls. Future processes that treat rail should not change the rail profile shape and 

should maintain a smoother running surface. 
30
31 

Appendix A. 

Laser-Glazed Rail Failure Analysis 

By Francisco Hernandez Robles, TTCI Principal Investigator 

A-1.0 Background 

The Transportation Technology Center, Inc. (TTCI), Pueblo, CO, received a rail sample that had 

been treated by a laser-glazing process. This sample was installed in the Facility for Accelerated 

Service Testing (FAST) at the Transportation Technology Center (TTC) in Pueblo, CO, for 

monitoring under heavy axle load (HAL) traffic (39 tons per axle). Shown in Figure A-1, a 

visual inspection before installing the rail in track showed possible signs of metallurgical damage 

in the regions where the rail had been treated with the laser-glazing process. Figure A-2 shows 

that after approximately 5.6 million gross tons (MGT) of HAL traffic, the glazed areas showed 

signs of chipping at the rail’s gage corner. Since the rail has shown a susceptibility to damage, 

the Federal Railroad Administration (FRA) and TTCI technical staff decided to remove the rail 

from the test. 

TTCI recommends that before installing any other laser heat-treated rails in track, a metallurgical 

analysis should be performed on the rail. The analysis will be used to document the 

metallurgical characteristics of the treated areas on the rail before and after being subjected to 

HAL traffic. 

Figure A-1. Figure 1(a). Laser-Glazed Treated Rail, 

Figure A-1(b). Rough, and Figure A-1(c). Uneven Glazed-Treated Gages 

for the Untested Rail 

1(a) 1(b)

1(c)
32 

 

A-2.0 Non-Destructive Testing (NDT) Analysis 

A-2.1 Visual and Non-Destructive Examination (Non-Service Tested Rail) 

A 6-foot piece of the rail was cut from the original rail sample. This section was used for the 

present metallurgical analysis in order to compare the effect of HAL traffic on the integrity of the 

glazed rail. The visual examination showed no cracks on the glazed regions; however, using 

magnetic particle and liquid penetrant inspections, several cracks were identified particularly 

along the regions where the two laser-glazed treatments overlap, as shown in Figures A-3(a) and 

3(c). No cracks were revealed in the cross section (Figures A-3(b) and 3(d)) of the rail by NDT 

techniques. 

Figure A-2. Figure A-2(a) Rail Removed from FAST Facilities After 

Approximately 5.6 MGT of HAL Traffic, Figure A-2(b). Macro-Picture 

howing Severe Wear, and Figure A-2(c). Macro-Picture Showing Shelling 

Regions of the Laser-Glazed Rail

S

2(b) 2(a)

2(c) 
33 

3(a) 3(b) 

3(c) 3(d) 

Figure A-3. Figures A-3(a) and 3(b). Macro-Pictures of the Laser-Glazed Rail Analyzed 

with Magnetic Particles. Figures A-3(c) and 3(d). Liquid Penetrant (Arrows in 3(d) Show 

Damage Caused with the Cutting Tool) 
34 

A-2.2 Visual and Non-Destructive Examination (Service-Tested Rail) 

The laser-glazed treated rail was removed from FAST after approximately 5.6 MGT of HAL 

traffic due to its susceptibility to shelling at the gage corner area (Figure A-2(c)). After the rail 

was removed from FAST, it was sectioned for analysis at TTC. Three pieces, 3-feet long, were 

shipped to Argonne National Laboratory. Figure A-4 shows a sketch of the sections of the rail 

and indicates the locations for sections sent to the Argonne National Laboratory, as well as the 

ones kept at TTC for analysis. An additional 2-foot portion of control rail was cut and is kept at 

TTC for future investigations (if required and/or requested). The present metallurgical analysis 

was conducted on Section V of the rail located between ties 590 and 600, approximately nine 

feet from either tie (See Figure A-1). 

The damage revealed by the NDT of the laser-glazed treated rail removed from FAST shows 

more severe damage at the gage corners when compared to the non-service tested rail. This 

damage is the result of increased susceptibility of the laser-glazed treated regions to cracking and 

shelling. Figure A-5 shows pictures of the magnetic particle analysis of the gage regions and the 

cross section of the rail. In the cross section of the rail, no cracks were revealed by the NDT 

methods used. 
35 

T A A T A T 

I II 

Tie 

590

III IV V VI VII VIII 

Tie 

600

IX X XI 

Sections I through XII (identified in the web of the rail) of the laser-glazed rail are 3’ in length, and Section XIII is 2through XIII will be kept at TTCI for future reference or analysis unless otherwise requested by Argonne National l

Head of the rail: 

Sections I through VI were used for analysis; the letters on the head of the rail indicate how these sections 

•• “T” indicates the specimens that were analyzed at; Section V was selected for the present metallurgic

Figure A-4. Sketch Showing Segments of Rail Used for Analysis at TTC, as Well as Sections Sent to Argon

“A” indicates the shipped sections to the Argonne National Laboratory. 

Thermite Weld 

38’ 8” 5/8 

3” 

Chip Chip 

Head 

Web 

Base

Chip Chip Chip 

Towards FAST Section 6 Towards FAST Section 
36 

5(a) 5(b)

5(c) 5(d) 

Figure A-5. Photographs of Magnetic Particles Analysis of Various Sections of Laser-Glazed Rail 

from FAST at Approximately 5.6 MGT of HAL Traffic Showing No Cracks in Cross Sectio

Figure A-5(a). Section Showing Shelling at the Gage Corner of the Rail. Figure A-5(b). Extended Cracks Along the Gage Corner of the Rail. Figures A-5(c) and A-5(d). Compare with Laser-Glazed Non-Service Tested Rai

Presents a Less Severe Damage 
37

A-3.0 Metallurgical Analysis 

The metallurgical analysis for the non-service tested rail was conducted on the previously 

mentioned 6-foot section extracted from the section of the rail sample indicated in Figure A-4, 

the original laser-glazed rail. The section used for the present metallurgical and NDT analysis 

was located between ties 590 and 600 (approximately 9 feet from either end tie). In addition, a 

metallurgical analysis for the untreated (field) corners of the non-service tested and servicetested rails was conducted. Both above-mentioned portions of rail were sectioned to obtain a 

set of six metallographic samples for each rail condition, three from the gage (laser-glazed) and 

three from the field sides of the rail. For the service-tested portion of the rail, two of the three 

samples were cut in close proximity to the shelled region to analyze the sections of the rail 

containing the most severe damage caused by HAL traffic. In addition, six charpy samples 

were extracted for every rail condition (service tested and non-service tested); three samples 

were from the gage corner and the other three from the field corner. Each sample was tested at 

different temperatures [-30° C (5° F), 0° C (32° F), and 65° C (175° F)] to investigate the 

effects of the laser-glazed treatment and the HAL traffic on the fracture mechanisms presented 

on the treated rail under different temperatures (environments). 

A-3.1 Stereoscopic Examination 

Subsequent to initial visual examination, the metallographic samples were micro-and macrographically examined. The metallographic samples were polished following standard 

procedures. Using the stereo-macroscope on both non-service tested and service-tested 

samples, several cracks across the glazed regions were identified. A description of the stereomacroscopic analysis conducted on the metallographic samples follows. 

Figures A-6(c) and 6(b) show that for the non-service tested rail, the macrographs of the laserglazed (gage, Figure A-6(b)) and (field, Figure A-6(c)) sections of the rail. The macrographs 

were taken at magnifications of 3.5x for Figure A-6(a), 45x for Figure A-6(b), and 3.5x for 

Figure A-6(c). In the gage side of the rail, cracks were found along the glazed regions. In all 

cases, the cracks did not propagate past the interface between the glazed region and the parent 

rail material. In contrast, the field side of the rail did not have cracks present. 
38

6a 

6b 

6(a) 

6(b) 

Figure A-6. Macrographs of Laser-Glazed Treated Rail at Gage Corner 

Showing Cracks Across Glazed Areas. Arrows Point to Cracks. 

Figure A-6(a). Macrograph with 3.5x Magnification 

Figure A-6(b). Macrograph with 45x Magnification 
39

Figure A-7 shows macrographs with magnifications at 3.5x (Figure A-7(a)) and 45x (Figure A7(b)) of the gage side of the laser-glazed rail removed from FAST after approximately 5.6 

MGT of HAL traffic. Cracks were observed at the gage region within the glazed areas. The 

circled aras show the cracks on the glazed region and parent rail material. Comparing Figures 

A-7(a) and 7(b) with Figures A-5(b) through 5(d), it is clear that an increase in the severity of 

the damage observed in the gage corner of the rail increased under HAL traffic. The 

stereoscopic analysis further confirms the previously mentioned damage on the microstructure 

of the laser-glazed rail. In addition, not only were perpendicular cracks to the glazing region 

identified, but also the cracks going into the parent rail branched, resulting in a web of cracks. 

The branched cracks can act as stress concentrators that promote premature failure of the rail 

particularly under cyclic fatigue conditions. Figure A-6(b) shows that the samples extracted 

from the field side from the non-service and service-tested samples did not contain areas with 

cracks or other damage associated with the laser-glazing process.

Figure A-6(c). Macrograph with 3.5x Magnification of Field Corner of 

Untested Rail Showing a Crack Free Microstructure 

6(c) 
40

Figure A-7. Macrographs of the Laser-Glazed Treated Rail Removed from 

FAST After Approximately 5.6 MGT of HAL Traffic 

A-3.2 Optical Microscopy Examination 

The microstructures of the laser-glazed samples were observed under various magnifications on 

both the polished and etched samples. The etching reagent used was NITAL 2 percent for ~3 

seconds at room temperature. The polished surface for the non-service tested (gage and field) 

microstructures contained a limited number of inclusions (probably sulphurs) visible at low and 

high magnification (Figures A-8(a) and 8(b) respectively). Figure A-8(c) shows the etched 

microstructure where various regions can be identified as in agreement with a previous report 

conducted on laser-glazed rails [Ref.1]. These regions contain martensite, amorphous areas 

(presumably the white zones in Figure A-8(c)), and, in the lower part of the sample, the 

unaffected (non-glazed) region showing the fully pearlitic structure. 

Laser Glazed Region 

Parent Rail 

7(a) 

7(b) 
41

8(a) 8(b) 

8(c) 

 Martensite 

Amorphous Region 

 Martensite 

Pearlite 

Figures A-8(a) and 8(b). Microstructure of the Laser-Glazed Region After Polishing. 

Figure A-8(c). Micrograph of the Various Regions Observed at the Glazed Regions 
42

Figure A-9 shows the etched microstructure of the glazed regions and parent rail material for 

the non-service tested rail. It shows the various microstructures presented by different zones of 

the rail in the glazed region (selected areas from Figure A-8). Figure A-9a shows the presence 

of martensite that is evident at magnifications of 200x and 500x. At 200x it can also be 

observed that the cracks end at the interface between the glazed region (martensite) and the 

unaffected parent material (pearlite; Figure A-9(b)). Figure A-9(c) shows overlapping of the 

two glazing treatments. Some porosity along the interface of both regions can be observed at 

200x in (Figures A-9(b) and 9(c)). The porosity was presumably created during the glazing 

treatment and is detrimental to the integrity of the rail. Figure A-9(d) at 200x shows a fully 

pearlitic region found in the parent rail material. 

9(a) 9(b) 

9(c) 9(d) 

Figure A-9. Etched Microstructure of the Glazed Regions and Parent Rail Material for 

the Non-Service Tested Glazed Rail. Figure A-9(a). Martensite (500x). 

Figure A-9(b). Crack Stopped at Interface Between Glazed Region and Unaffected 

Parent Rail (200x). A-9(c). Overlapping of Two Glazing Treatments (200x). 

Figure A-9(d). Peralitic Region in Parent Rail Material (200x) 
43

Figure A-10 shows the polished microstructures of the glazed region of the service-tested rail. 

The number, location, and severity of the cracks observed on the gage sides for the servicetested rail (5.6 MGT of HAL traffic at FAST) has increased considerably. For instance, Figure 

A-10(a) shows a crack that ended at the interface between the glazed region and the parent rail 

material and a crack that ramified into the parent rail material. Figure A-10(b) shows a crack 

along the glazed region of tested rail removed from FAST after approximately 5.6 MGT of 

HAL traffic. This crack was likely created from the shelling of the glazed treated surface under 

HAL traffic. Figure A-10(c) shows a crack across the laser-glazed region where both laserglazed treatments overlap. In both ends the crack ramified (arrows indicate the interface). It is 

a good example of the possible residual stresses created due to the glazing treatment that 

created regions highly susceptible to cracks. This is further assisted by the martensite 

formation. The above-mentioned residual stresses promote susceptibility to crack formation, in 

particular to cracks in the gage surface and the interface between the glazed regions and the 

parent rail material. This accelerates the progress of shelling. 

Figure A-10(a). A Crack Ending at the Interface Between the Glazed Region and Parent 

Material and a Crack that Ramified Into the Parent Rail Material 

10(a)
44

10(b) 

10(c) 10

Figure A-10(b). A Crack Along the Glazed Region. 

Figure A-10(c). A Crack Across the Laser-Glazed Region 

Where Both Laser-Glazed Treatments Overlap
45

Figure A-11 shows the etched microstructure of the glazed regions and parent rail materials for 

the rail removed from service after approximately 5.6 MGT of HAL traffic. Micrographs in 

Figure A-11 are magnified areas of the micrographs shown in Figure A-9(b) after etching. 

Figure A-11(a) shows micrographs on the etched microstructure of the various phases that form 

in the microstructure. The regions where sequential glazing treatments overlap present sections 

with sharp edges acting as stress concentrators. These build up stresses that can be detrimental 

and can compromise the integrity and service characteristics of the rail, resulting in crack 

formation (Figure A-11(b)). Figure A-11(c) shows sharp needles of lath martensite that formed 

at the interface between the glazed region and the parent rail material. The microstructure of 

the parent rail material is comparable to the non-glazed rail (field section) that is fully pearlitic. 

11(a) 11(b) 

11(c) 11(d) 

Figure A-11. Micrographs of the Etched Microstructure of the Service-Tested Glazed Rail. 

Figure A-11(a). Affected Regions of the Rail by the Glazed Treatment (50x). 

Figure A-11(b). Overlapping of Both Glazed Treatments (200x). 

Figure A-11(c). Zones Showing Sharp Laths of Martensite (1,000x). 

Figure A-11(d). Pearlitic Regions of the Parent Rail Material (200x) 
46

Figure A-12 shows the microstructures of the rail’s field sections. For the field regions, only a 

set of pictures for the non-service tested and the service-tested rails is presented since the 

microstructure in either case shows no significant differences under various magnifications up 

to 500x. After polishing, the microstructure shows a low amount of inclusions, probably 

sulphurs; on the other hand, the etched microstructure is fully pearlitic as expected. 

12(a) 12(b) 

12(c) 12(d) 

Figures A-12(a) and 12(b). Microstructure for the Laser-Glazed Rail Showing as Polished Surface. 

Figures A-12(c) and 12(d). Etched Microstructure. 

Figures A-12(a) and 12(c). 50x Magnification. 

Figures A-12(b) and 12(d). 500x Magnification 
47

A-3.3 Mechanical Testing 

A-3.3.1 Micro-Hardness Test 

Four specimens for non-service tested and service-tested rail conditions (two from the gage 

sides and two from the field sides, respectively) were tested for micro-hardness. The microhardness measurements were conducted, as shown in Figure A-13. The micro-hardness 

measurements at the edge (profile) of the sample for the field sections were conducted only for 

one non-service tested and one service-tested sample since the micro-hardness measurements 

were consistent. Table A-1 presents a summary of the micro-hardness measurements results 

and the statistical analysis of the results for the Left (L), Center (C), and Right (R) diagonals 

and the Edge (E) regions of the analytical samples. The micro-hardness of the gage of the rail 

(glazed-treated section) was very consistent and comparable to the micro-hardness obtained on 

the field side of the rail. The micro-hardness of the parent rail material averaged 414.1 ± 27.2 

HV; for the gage (laser-glazed) region, the micro-hardness averaged 881.75 ± 92.1 HV. The 

higher standard deviation presented in the gage side along the glazed region is the result of the 

lack of integrity and homogeneity of the glazed regions that are mainly composed of 

amorphous [Ref. 1] and martensitic regions or zones. 

Figure A-13. Sketch of the Micro-Hardness Measurements as 

Conducted for the Tested and Non-Tested Sections of the 

Investigated Samples. The Micro-Hardness Measurements 

Were Conducted Along L, C, R, and E Regions 

40/10000 

i

L 

C

R

E
48

Table A-1. Results of the Micro-Hardness Analysis for the Gage and Field Samples Under 

Non-Service Tested and Service-Tested Conditions (for more detail see Figure A-13) 

Standard Confidence Confidence Average (HV) Deviation (HV) Limit (95%) Limit (99%) 

Non-Service Tested Rail “Field” 

Left 398.8 22.6 9.1 11.9 

Middle 404.6 24.5 9.8 12.9 

Right 385.8 40.3 16.1 21.2 

Non-Service Tested Rail “Gage” 

Left 429.2 23.2 9.3 12.2 

Middle 424.8 23.6 9.4 12.4 

Right 418.1 21.6 8.6 11.3 

Edge 857.1 56.3 29.6 29.6 

Service-Tested Rail “Field” 

Left 418.4 26.4 10.6 13.9 

Middle 421.7 23.2 9.3 12.2 

Right 436.6 19.5 7.8 10.3 

Edge 400.6 26.1 10.4 13.7 

Service-Tested Rail “Gage”

Left 404.8 18.9 7.6 9.9 

Middle 420.5 27.3 10.9 14.3 

Right 496.4 17.7 7.1 9.3 

Edge 917.9 121.3 48.5 63.4 

A-3.3.2 Charpy Test 

Six specimens (three from the gage and three from the field side) for non-service tested and 

service-tested conditions were extracted and machined according to the E370 American Society 

for Testing and Materials (ASTM) standard. Impact charpy tests were carried out at various 

temperatures (-30° C (5° F), 0° C (32° F), and 65° C (175° F)) to investigate the effect of the 

glaze treatment on the fracture mechanism for the steel at extreme temperatures for revenue 

service. Table A-2 shows the results of the energy absorbed by the sample during the impact 

(charpy) test. From Table A-2, it can be concluded that the energy absorbed during the impact 

test increased with temperature, which is expected; nonetheless, all fractures observed were 

brittle with limited deformation presented by the samples (Figure A-14). Figures A-14(a) 

(field) and 14(b) (gage) are non-service tested conditions. The above-mentioned increase in 

energy (for the samples extracted from the field regions) is more indicative that the glazed 

treatment reduced the impact toughness. Furthermore, the affected regions with the internal 

damage are severe, resulting in one of the samples fracturing away from the notch region 

(Figures A-14(c) and 14(d)). Figure A-14(d) has a dotted line that circles the notch of the 

sample. Severe damage was caused during the machining of the notch due to the high 

brittleness probably created by the martensite. Results suggest that the glaze treatment can 

form stress concentrations considerably larger than the ones created by the engineered notch 

typically machined for the charpy samples. 
49

Table A-2. Results of the Charpy Test Conducted for Samples Extracted from the Gage 

(Glazed) and Field Regions for Non-Service Tested and Service-Tested Conditions 

Absorbed Energy in Ft2/Pound 

Sample/Testing 

Temperature -30° C (5° F) 0° C (32° F) 65° C (175° F) 

3.8 (gage) 5.0 (gage) 5.7 (gage) Non-Service Tested 4.2 (field) 5.5 (field) 8.0 (field) 

3.5 (gage) 4.3 (gage) 6.0 (gage) Service-Tested 4.5 (field) 5.75 (field) 8.5 (field) 

14(a) 14(b) 

14(c) 14(d) 

Notch Crack 

Figure A-14. Pictures of Selected Charpy Tested Samples Showing Fresh Fractures 
50
A-4.0 Conclusions 

The use of laser-glazing technology for the railroad industry as a substitute for rail lubrication 

is an interesting prospect that requires further investigation. The possibility of reducing the 

roughness of rail at the gage corner by creating a hard surface would reduce the friction 

between the rail and the wheel. This has a potential application to reduce or eliminate the use 

of lubricants for revenue service in curves. Nonetheless, the current technique is only capable 

of reducing the roughness in a discrete manner rather than continuously (see Figures A-1b and 

A-1(c) for details). In addition, the integrity and service characteristics of the glazed regions 

compromise the survivability of this type of treated rail in revenue service. 

For many applications, wear is associated with the hardness of the material; however, previous 

reports by TTCI [Ref. 2] showed that this is not necessarily the case. In fact, the mechanisms 

that influence the different phases to deform and fracture are as important for wear resistance, 

integrity, and service characteristics as the materials themselves. The present analysis is a good 

example, since the transformation of pearlite to martensite by the laser-glazed treatment is 

simple since martensite is considerably harder than pearlite. However, the transformation of 

austenite, which is the face cubic centered phase that is found at temperatures between ~800° C 

(~1,550° F) and ~1,200° C (2,200° F), for the investigated alloy to martensite by a rapid 

cooling is conducted by shear. This sheer creates residual stresses. The residual stresses in the 

overlap of both treatments could be in tension or compression, resulting in areas or regions that 

are sensitive to crack formation and aid crack propagation (see Figures A-10(c) and A-14). 

Sawley, in Reference 1, mentions that the laser-glazed treatment can increase the rail’s 

temperature well up into the austenitic region (~900° C or ~1,650° F). The characteristics of 

the treated glazed rail tested in service for the present analysis, however, show a surface with 

the typical characteristics of a re-melted material. This may indicate that the temperature 

reached by the rail’s surface during the glazing treatment was considerably higher, in the range 

of the semi-solid or liquid state temperatures (>1,200° C (2,200° F) for this alloy). 

The heat affected zone is well localized into the glazed region and makes this treatment worth 

further study, since the parent rail material (fully pearlitic microstructure) appears to be unaffected (compare the microstructures and micro-hardness of the pearlitic regions for gage and 

field regions in Figures A-9 through A-11). The above argument further confirms the reasons 

for the abrupt increase in micro-hardness from less than 440 HV to more than 1,000 HV in a 

distance of less than 0.001 inch (interface). 

51
52
53

A-5.0 Recommendations 

It is recommended that all laser-glazed treated rails undergo a full metallurgical evaluation to 

determine their integrity before their use in revenue service. It is suggested that no glazed rail 

presenting the characteristics of the samples investigated at TTC be subjected to service traffic, 

either at FAST or revenue service. This recommendation does not include the elimination of 

the laser-glazed treatments for standard and/or premium rails but rather encourages the 

optimization of the technique. An optimized technique would ideally heat treat the rail’s 

surface by heating the rail to the austenitic temperature, avoiding an overheat of the rail that 

could reach the semi-solid or liquid states. This would keep intact the integrity of the rail’s 

surface, minimizing or eliminating cracks and residual stresses. The treatment that is proposed 

would transform a small region of the surface into bainite, martensite, or a combination of 

phases and at the same time form a smooth hard shell. This, however, raises the following 

questions that will help to further optimize the laser-glazed technique: 

• Is a harder phase (other than pearlite) the alternative to maximize the wear life 

of the rail? 

- If so, why did steels like J6 steel (fully bainitic [Ref. 2]) not perform as 

expected under HAL service traffic operation at FAST? 

• What will happen once the laser-glazed treated surface wears out? 

• Will the higher hardness of the laser-glazed treated rail wear the wheels more 

rapidly? 

• Is there a methodology to glaze the rail in-track for revenue service? 
54
55

A-6.0 References 

1. Sawley, K. and J. Sun, “Laser Glazing to Reduce Rail Wear,” Technology Digest TD97-024, Association of American Railroads, Transportation Technology Center, Inc., 

Pueblo, CO, July 1997. 

2. J. Kristan, “FAST Rail Evaluation Test–Fracture Performance and Discussion,” 

Technology Digest, TD-05-024, Association of American Railroads, Transportation 

Technology Center, Inc., Pueblo, CO, October 2005. 

3 Welsch, G.E., “Iron–Carbon/Cementite Phase Diagram,” ASM International, Materials 

Park, OH, 1994. 
56
57

Appendix B. 

Nuvonyx Laser-Glazing of Rail 

for AAR/TTCI FAST Loop Tests 
58
59
60
61
62
63
64
65
66
67

Acronyms 

DOE Department of Energy 

FAST Facility for Accelerated Service Testing 

FRA Federal Railroad Administration 

HAL heavy axle load 

HH heat-treated head hardened rail 

HTL High Tonnage Loop 

MGT million gross tons 

TTC Transportation Technology Center (the facility) 

TTCI Transportation Technology Center, Inc. (the company) 
68