OCT 2 4 1968

NATIONAL BUREAU OF STANDARDS REPORT

Examination of

CADMIUM PLATED FUSE BODY REAR

HOUSING COMPONENTS

To

Harry Diamond Laboratories

9927

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards1 was established by an act of Congress March 3,

1901. Today, in addition to serving as the Nation’s central measurement laboratory,

the Bureau is a principal focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. To this end the Bureau conducts research and

provides central national services in three broad program areas and provides central national services in a fourth. These are: (1) basic measurements and standards,

(2) materials measurements and standards, (3) technological measurements and

standards, and (4) transfer of technology.

The Bureau comprises the Institute for Basic Standards, the Institute for Materials

Research, the Institute for Applied Technology, and the Center for Radiation Research.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the

United States of a complete and consistent system of physical measurement, coor- dinates that system with the measurement systems of other nations, and furnishes

essential services leading to accurate and uniform physical measurements throughout

the Nation’s scientific community, industry, and commerce. The Institute consists

of an Office of Standard Reference Data and a group of divisions organized by the

following areas of science and engineering

Applied Mathematics—Electricity—Metrology—Mechanics—Heat—Atomic Physics—Cryogenics2—Radio Physics2—Radio Engineering2—-Astrophysics2—Time

and Frequency.2 THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to methods, standards of measurement, and data needed by industry, commerce,

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1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted ; mailing address Washington, D. C. 20234.

2 Located at Boulder, Colorado 80302.

3 Located at 5285 Port Royal Road, Springfield, Virginia. 22151.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT

872064

1

OCT 2 4 1968

NBS REPORT

9927

Examination of

CADMIUM PLATED FUSE BODY REAR

HOUSING COMPONENTS

By

W. F„ Gerhold

Engineering Metallurgy Section

Meta 1 1 urgy Division

To

Harry Diamond Laboratories

IMPORTANT NOTICE NATIONAL BUREAU OF 5 for use within the Government

and review For this reason, whole or in part, is not auth Bureau of Standards. Washing

the Report has been specifical

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

ress accounting documents intended

s subjected to additional evaluation

re listing of this Report, either in he Office of the Director, National by the Government agency for which

copies for its own use <nb§>

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

U. $. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, D.C„ 20234

Exami nation of

CADMIUM PLATED FUSE BODY REAR

HOUSING, COMPONENTS

Submitted by

Harry Diamond Laboratories

NBS Project 8720641

HDL Project No, 70470

By

W„ F. Gerhold

Division 3)2.01

Reference : (a) HDL Work Order, HDL Project No. 70470.

Mater i a I : Three cadmium plated rear housing components fabricated from

AISI B1112 resulfurized carbon steel were submitted under Reference (a)

for examination. The components are cylinders that have been machine

bored at each end leaving a thin section separating the two bores.

Failures have been reported in certain lots of these components. It was requested that the cause of failure of the components be determined.

Of the three specimens submitted, one was reportedly fabricated from

a leaded AISI B1I12 carbon steel and was from a lot in which no failures

had been reported. The other two components were specimens that had

failed and were reportedly fabricated from a non-leaded AISI B1I12 carbon

steel. One of these specimens failed in an "out-of- I i ne" test conducted

in England and was from a lot in which prior failures had occurred. The

third specimen failed in an "out-of- 1 i ne" test conducted at HDL and was from a lot in which no prior failures had been reported.

Visual Examination : Visual examination of the two specimens that had

failed, revealed that in each case, the cylinder walls of the larger of

the two bores had fractured. The fractures occurred in the area adjacent to one of the small drilled holes used to line up the detonating

mechanism. On one of the specimens, the fracture was complete and a portion of the cylinder wall was missing. The fracture on the other

specimen was incomplete and the wall was still intact on one side of the

fracture, arrow c in Figure 1.

2

Each specimen was sectioned through the bore. Examination of the base

of the large bore of each of the specimens that had failed revealed that

the radius at the junction of the base and the cylinder wall was quite

sharp. In addition, tool markings from the machining operations appeared

excessively deep. These conditions are shown in Figures 1 and 2 .

In contrast there was a slight radius between the base and the cylinder

wall on the specimen which had not failed. Figure 3 . Tool markings on this

specimen were quite shallow compared with those noted on the specimens that

had fai led.

Sharp radii at fillet areas and deep tool markings act as stress raisers.

In areas where these conditions exist, such as in the bore at the junction

between the base and the cylinder wall, localized stresses are greatly

intensified when a load is applied. Thus the concentrated stress induced

at the junction of base and wall at the time of detonation could be greater

than the design limits of the part. The result would be failures of the

type found.

Chemical Analysis : Chemical analyses were obtained for each of the specimens

for conformance to chemical composition of A 1 SI 81112 resulfurized carbon

steel. These results compared with that specified in Fed. Std.No. 66c

are given below.

Specimen No. Chemical Composition, Percent

C Mn P s Pb

1 0. 12 O.85 0.08 0.22 0.28

2 0.13 O.96 0.09 0.17 0. 19

3 0.10 O.96 0. 10 0.18 0. 19

Fed. std. No. 66c 0.13 max 0.70/1 .00 0.07/0. 12 0. 16/0.23 *

* Pb if specified is generally added in a range of 0 . 15 / 0.35 percent.

(a) No. 1 - leaded B 1 1 1

2

resulfurized carbon steel.

No. 2 - B 1 1 12 resulfurized carbon steel -- from test conducted in England

No. 3 “ B 1 I 12 resulfurized carbon steel -- from test conducted at HDL.
. s
- 3 -

The composition of all of the specimens was within that specified for

AISI BI1I2 resulfurized carbon steel. All could be considered leaded

steels, although the one reported to be a leaded steel contained more lead

than the other two.

Hardness : Vickers (10 Kg load) hardness determinations were obtained from

samples of the three specimens. These determinations converted to Rockwell

B along with corresponding approximate tensile strength values were:

(a)

Specimen No. Hardness, R DD TS,

1 78 71

2 85 80

3 88 85

( 3 ) No. 1 - leaded AISI B1112 resulfurized carbon steel.

No. 2 - AISI B1112 resulfurized carbon steel from test

conducted in England.

No. 3

" AISI B1112 resulfurized carbon steel from test

conducted at HDL. *

The hardness of the two specimens tnat had failed was higher than that

which had not failed. However, the difference is not considered to be of a sufficient magnitude to be considered deleterious.

Meta 1 lographi c Examination : Sections were cut from each of the specimens

for meta 1 lographi c examination. The results of this examination revealed

that in each instance. Figures 4a, b, and c, the materials was in the

annealed (soft) condition. The matrix of each was predominantly ferrite

with pearlite. Areas containing included material, sulfides, were also noted.

Sulfide inclusions are generally found in all steels of this type and are not

considered harmful. Lead, in the quantity determined by chemical analysis,

would be so finely dispersed as to be undetectable by the usual meta 1 1 ograph i

c

methods

.

Cone 1 us i ons : Examination of failed fuse body rear housing components

indicated that the failures were caused by a lack of a sufficiently large

fillet between the cylinder wall and the base of the large bore. There were

indications that deep tool markings at these areas may also have contributed

to the failures. These conditions resulted in an increase in stress con- centration at the time of detonation which was beyond the design limits for

the components.
. ' •

,
4

Chemical analyses of the steel used in the fabrication of each of the

components was in conformance with that specified in Fed. Std. No. 66c for

AISI BI1I2 resul f ur i zed carbon steel. However only one specimen was reported to have been fabricated from a leaded steel. All specimens

contained lead in sufficient quantities for the steel to be considered a

I eaded stee 1 .

Meta 1 lographi c examination of sections cut from each of the specimens

did not reveal any condition which could have been a contributory factor

toward fa i 1 ure

.

It is recommended that machining requirements be specified such that

there will be as generous a fillet as possible at the junction of the base

of the bore and the cylinder walls and that final machining operations are such that deep tool markings are eliminated.
1 '
d

Figure 1. Specimen that had failed in rr out-of- 1 i ne" test conducted

at HDL. Fracture was incomplete at one end in area noted

by arrow c and complete at other end, arrow d. Arrows a and b denote areas where there was an abrupt change in

contour. Note lack of fillet at these areas as contrasted

with that shown in Figure 3 . Deep tool markings were also

noted on sides of cylinder walls adjacent to these areas.

X 2

Figure 2. Specimen that had failed in "out-of- 1 i ne" test conducted

in England. Fracture was complete, areas noted by arrows

c. Arrows a and b denote similar areas shown in Figure 1. Note lack of fillet at these areas compared with those

shown in Figure 3. Deep tool markings were also noted

on sides of cylinder walls adjacent to these areas. X 2

Figure 3. Leaded AISI B1112 resulfurized carbon steel specimen from

a lot in which no failures had been reported. Note that

here there is a slight fillet at the areas (arrows a and

b) where there is a change in the contour of the part.

Tool markings from the machining operations were shallow

compared to those noted on specimens shown in Figures 1 and 2. X 2
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