bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneity of coarsened oxide inclusions in C-Mn steel welds
Authors: Powell G. L. F. , Lloyd P. G. , Bee J. V.
Published: January 2014

A preliminary investigation of the coarsening of oxide inclusions has shown that the heterogeneous nature of the oxide inclusion, i.e. crystalline particles in a glassy matrix, is retained in the coarsened inclusions. There is evidence that the crystalline particles may grow during the coarsening process.
Real time torch height detection technique for gas metal arc CO2 welding
Authors: Orszagh P. , Kim Y. C. , Horikawa K.
Published: January 2014

This paper describes results achieved in the development of a new type of welding torch position sensor, which enables real time measurement of the torch–workpiece distance in gas metal arc welding with shortcircuiting metal transfer. The sensor is based on a detection algorithm which enables extraction of the torch–workpiece distance from welding current and voltage waveforms, regardless of large variations in the instantaneous values of welding parameters. It was found that the torch–workpiece distance could be reliably obtained from wire resistance data during a shortcircuit state of the welding process. The sensor was tested under various welding conditions and its applicability was confirmed by real time monitoring of the sensor signal.
Chill zone formation in Al–Li alloy welds
Authors: Reddy G. M. , Gokhale A. A. , Prasad K. S. , Rao K. Prasad
Published: January 2014

The presence of a fine equiaxed zone (also known as the ‘chill zone') along the fusion boundaries in Al–Li alloy welds has recently been reported. Preferential failure along the chill zone during tensile testing has also been observed. Such zones have not been reported in other aluminium alloy welds. The chill zone was considered to form as a result of high undercooling during solidification of Al–Li alloys. In another study, Al3(Li,Zr) aided nucleation was proposed to be the mechanism of nucleation of the chill grains. The present work demonstrates that the chill zone forms only under conditions when the base alloy contains Al3Zr particles before welding. The presence of Al3Zr particles within the chill grains has been shown for the first time. The grain structure of the base metal does not have any role in the formation of the chill zone. A chill zone is also observed in a non-Li bearing Al alloy which contains Zr. It is further shown that in pulsed current and oscillating arc welds, the chill zone is not restricted to the fusion line (as in continuous current welds), but also occurs in the weld interior.
Joining steels with electrodeposited nickel or copper barrier layers using Cu–P brazes
Authors: Eagles A. M. , Mitchell S. C. , Wronski A. S.
Published: January 2014

To prevent the formation of continuous brittle phosphides when steel is brazed with Cu–P–Sn alloy, barrier layers were deposited on the steel: nickel on stainless steel and copper for mild steel. Their effectiveness is demonstrated by the increase in the lap shear strength from <10 to 160 MPa for the mild steel joints and from 80 to 136 MPa for those with stainless steel. The microstructures of the brazements were investigated by optical and scanning electron microscopy (including microprobe analysis) to ascertain the reactions and mechanisms occurring at the intermediate layer interfaces – both with the basis metal and with the braze alloy. Interactions involving the barrier metal result in the formation of a solid solution with discrete particles of complex compositions in the interfacial region. These reactions are analysed and the resultant phases identified. Optimisation of brazing time and temperature and of the layer thickness resulted for both systems in (near) complete elimination of the phosphide particles in the joint zones adjacent to the parent metal. The suppression of the continuous brittle interfacial phosphide layer enhances the mechanical properties of the joints.
Modelling mushy zones in welds of multicomponent alloys: Implications for solidification cracking
Authors: DuPont J.N. , Robino C.V. , Marder A.R.
Published: January 2014

A method is proposed for calculating the variation in fraction liquid with distance in the mushy zone as an aid to determining the effect of alloy additions on solidification cracking susceptibility. The model combines the general liquidus equation of a multicomponent system, solute redistribution relations, and temperature gradient information. Calculations are presented for a range of niobium bearing superalloys and the results were found to reveal important relations between alloy composition, variation in fraction liquid with distance in the mushy zone, and cracking susceptibility as measured by the Varestraint test. In particular, the results directly show that the addition of carbon to these alloys is generally beneficial because it reduces the size of the crack susceptible mushy zone and limits the amount of terminal liquid available for the low temperature L → γ + Laves reaction. The modelling results and experimental data are also used to describe the influence of other alloy additions.
Variable polarity plasma arc welding of 6·35 mm aluminium alloys: Parameter development and preliminary analysis
Authors: Woodward N.J. , Richardson I.M. , Thomas A.
Published: January 2014

The application of the variable polarity plasma arc welding (VPPAW) process to two medium to high strength 6·35 mm thickness aluminium alloys is described. Automated computer controlled equipment was used to produce single pass, full penetration keyhole welds of even bead width. The paper covers the development and optimisation of the welding parameters and different material preparation procedures, providing macrographs, electrical transient traces, hardness profiles, and tensile results from some of the welds made. Repeatable procedures were obtained more easily by welding in the vertical up position, using the plasma gas flowrate in conjunction with the welding current to generate the desired bead profile. Autogenous welded joints were found to provide adequate root reinforcement with a slight degree of undercutting at the top bead. Example skimmed and as welded tensile tests were carried out on 2024 alloy, resulting in a typical overall ultimate tensile welded performance of 66% of the parent strength.
Stress corrosion behaviour of nickel superalloy weldments
Authors: Wu W. , Cheng T.P. , Hsu W.H.
Published: January 2014

Alloys 690 and 600 were welded to type 304L stainless steel using Inconel 82 as a filler. The investigation involved evaluation of the weldment's resistance to stress corrosion cracking (SCC). Results of slow strain rate testing in a simulated pressurised water reactor environment showed that alloy 600 is more susceptible to SCC than alloy 690. However, both nickel alloys have superior resistance to SCC compared with type 304L stainless steel. The Inconel 82 weld metal developed an extremely dense oxidation layer which could not be removed by a stainless steel brush and may require use of a grinder to ensure a sound weld.
Effect of surfactant redistribution on weld pool shape during gas tungsten arc welding
Authors: Winkle C. , Amberg G. , Inoue H. , Koseki T. , Fuji M.
Published: January 2014

In previous evaluations of GTA welding on stainless steel plates the surfactant content in the workpiece has been assumed to be in a state of equilibrium. However, surfactant concentration usually had to be adjusted in order to achieve agreement between the weld pool shapes in experiments and those in simulations. In this study a physicochemical approach to the redistribution of surfactant at the surface and in the bulk is presented for the first time. Sulphur was considered as a representative surfactant. The model allows surfactant molecular transport via convection, diffusion, and sorption. It is shown that sulphur atoms accumulate at the surface at stagnation points, affecting the coefficient of surface tension and thus the final weld pool shape. Thus, the sulphur content in the simulation approaches the nominal sulphur content in the steel plate. The theory is strengthened by both electron probe microanalysis and Auger electron spectroscopy.
Problems and solutions in deep penetration laser welding
Authors: Matsunawa A.
Published: January 2014

Keyhole dynamics in the high power continuous wave laser welding of aluminium alloys, in particular the role of keyhole instability in porosity formation, is discussed on the basis of high speed X-radiography observations. Motion in the weld pool was observed by introducing fine tungsten particles into the weld pool. A depression which moved periodically up and down the back wall of the keyhole gives rise to porosity, through bubbles formed at the bottom of the keyhole. The depression appears to be related to non-uniform evaporation on the front wall of the keyhole; both the keyhole and the weld pool are strongly disturbed by the dynamic pressure of the metallic vapour jet. The characteristic spherical and elongated pores were found to contain predominantly metal vapour and entrained shielding gas. Keyhole fluctuation in continuous wave laser welding can be suppressed by controlled pulse modulation, provided a suitable pulse frequency and duty cycle are selected.
Ultranarrow GMAW process with newly developed wire melting control system
Authors: Nakamura T. , Hiraoka K.
Published: January 2014

An ultranarrow gap GMA welding (UNGW) process with less than 5 mm gap width has been developed in which the arc pole is strongly oscillated over the groove wall in the thickness direction. A simulation model for wire melting tip behaviour with dc pulse current has been proposed and verified by observation of the tip motion in the UNGW groove. This simulation can define the optimum welding conditions to avoid welding defects. A synchronised control system consisting of a pulsed arc current waveform with cyclical variation of wire feed rate has been successfully developed on the base of the computer simulation. The newly developed UNGW system makes it possible to reduce arc heat input density sufficiently to produce an excellent weld joint with a narrow (1–2 mm) HAZ. Penetration shape control can also be achieved by this control method.
Development of high power CO2 laser welding process
Authors: Tsukamoto S. , Kawaguchi I. , Arakane G. , Honda H.
Published: January 2014

A deep penetration CO2 laser welding process has been developed as a low heat input, high efficiency fabrication route for advanced structural steels. To improve fundamental understanding of the process and facilitate the elimination of welding defects, the laser–plasma interaction has been characterised using a power probe, infrared spectroscopy, and high speed photography of monochlomatic images. The extent of the laser induced plasma was found to increase on raising the laser beam focal point from below the surface to the surface position. Plasma absorptivity was strongly affected by plasma composition, and hence by vapour generated by inhomogeneous melting of the keyhole wall; this effect exerts an important influence on keyhole instability. Variation in the keyhole wall profile as a result of inhomogeneous melting has been found to lead to porosity through the generation of bubbles that fail to escape from the weld pool. It is shown that appropriate pulse modulation of the laser beam can improve keyhole stability, thereby greatly reducing porosity in the welded joint.
Recent developments in underwater wet welding
Authors: Rowe M. , Liu S.
Published: January 2014

Developments in underwater wet welding processes over the past 25 years are reviewed. Shielded metal arc welding with rutile base coated electrodes is still by far the most common wet welding process in use. Research and development of wet welding electrodes has led to improvements in the control of hydrogen content, porosity, chemical composition, and microstructure of the weld metal. Additional work is required to develop welding consumables with improved control over diffusible hydrogen and porosity. Development of techniques such as temper bead welding has allowed successful wet welding repairs on steels having carbon equivalents greater than the traditional limit of 0.40. Alternative wet welding processes such as flux cored arc welding and friction welding are under development, but have yet to become widely accepted.
Plasma Nitriding of Gear Wheels in Mass Production
Authors: Roelandt A. , Elwart J. , Rembges W.
Published: January 2014

Detailed studies carried out by the Ford Motor Co. and the Machine Tool Institute of the Rhine-Westphalian Technical University in Aachen have shown that plasma nitriding can replace conventional carbonitriding case hardening treatments in gearing applications. It has been demonstrated that root and flank strengths comparable with those produced on case hardening gears can be obtained. The use of the process has enabled both operating and manufacturing costs to be substantially reduced. As a result of this investigation, Ford has installed a plasma nitriding unit in its tractor plant in Antwerp, Belgium. This unit is fully integrated into the production lines and is capable of treating a range of gear components.
Introduction to Lubrication Design Technology
Authors: Frelin B.
Published: January 2014

The requirements and important qualities of a lubricant are considered and a general description of the behaviour of lubricants under operating conditions is given. The influence of a component's surface roughness on its wear behaviour is discussed, with particular reference to the types of wear that can be identified. Example calculations using nomograms are shown. In these examples the oil film thicknesses required to provide sufficient lubrication under three types of wear contact (gears, and rolling and journal bearings) have been determined.
LASER Melt-Particle Injection Processing
Authors: Cooper K. P. , Ayers J. D.
Published: January 2014

In situ metal matrix-ceramic composite layers on metal surfaces were formed by injecting metal carbide particles into laser melted pools. Injected layers up to 2 mm thick and containing up to 60 vol.-% carbides were produced. Injected surfaces exhibited high hardness, up to × 2·6 that of the base metal and erosion wear resistance of up to × 38 that of the base metal. Reasonable control of injected layer characteristics such as penetration depth and carbide distribution and volume fraction was demonstrated. Utilizing a laser beam oscillation technique, strips up to 10 mm in width were produced with a single melt pass. Microstructural and microhardness analysis showed variations in the degree of carbide dissolution across the injected layer. Test specimens designed for sliding contact and impact rub wear were fabricated with the oscillating beam technique. Preliminary results showed WC and TiC injected Ti-6Al-4 V alloy surfaces to be unsuitable for impact wear applications, but WC injected Inconel 625 appeared promising for certain sliding wear applications.
Exploitation of Metallic Glasses through Surface Engineering
Authors: Roper G. W.
Published: January 2014

Metallic glasses are formed when certain alloy compositions are cooled very rapidly from the liquid state. They show a range of potentially valuable magnetic, electrical, mechanical, and corrosion properties, but their usefulness has hitherto been limited by the form in which they are generally produced, i.e. in, very thin sections. Ways in which this problem may be overcome for different applications are reviewed. For the purpose of exploiting the wear and corrosion properties of metallic glasses, it is considered that laser glazing holds considerable promise.
Engineering Applications and Analysis of Hardining Data for Laser Heat Treated Ferrous Alloys
Authors: Molian P. A.
Published: January 2014

Published information on the wide range of industrial applications in which laser surface transformation hardening has been used on ferrous alloys is reviewed. The effect of operational parameters on the heat treatment response (case depth, coverage rate, distortion, and hardness) is surveyed and illustrated from the results of a study of laser heat treatment of ASTM class 40 grey and class 80–55–06 ductile cast irons. Attempts are made to establish the relationship between the case depths obtained and the applied laser and material variables, on the basis of experimental data and heat flow models, and the available published data in this field are tabulated.
Relaxation of Shot Peening Induced Compressive Stress during Fatigue of Notched Steelsamples
Authors: Bergström J. , Ericsson T.
Published: January 2014

This paper presents an experimental investigation of the surface residual stress relaxation behaviour of a shot peened 0.4% carbon low alloy steel under fatigue loading. A round specimen with a circumferential notch and a notch factor Kt = 1.75 was fatigue loaded in both shot peened and ground conditions. Loading conditions included axial fatigue with stress ratio R = −1 and R = 0 and also R = −1 with an additional peak overload applied at 106 cycles. Plain unnotched shot peened specimens were also fatigue loaded with stress ratio R = −1. The results show how the relaxation is dependent on load level, how the peak load changes the surface residual stress state, and that relaxation of the smooth and notched conditions is similar. Two different shot peening conditions were used, one with Almen intensity of 30–35A (mm/100) and another of 50–55 A (mm/l00).
State of the Art of Factory Applied Protective and Decorative Plastic Coating Finishes
Authors: Brooks M. F.
Published: January 2014

The use of plastic coatings to protect or decorate metallic substrates may be seen by many to be a black art or, more crudely, bucket chemistry. This is far from reality. It is therefore the intention of this paper to dispel any myth relating to plastic finishing and demonstrate that several factors must be considered before the application of a plastic coating can satisfy the engineer's particular need. Whether one is desirous of protection against corrosion, a decorative and aesthetic finish, or a combination of cosmetic and anticorrosion characteristics, the design of the component to be coated, the attention to substrate preparation, and the selection of the coating medium should be the main features considered. Unless agreement between the designers, specifiers, and coating contractors can be reached on these fundamental concepts, the coating may not be able to perform the task required of it. The coating is often the final stage in a long line of activities and, being the first thing the user sees, often attracts unfair criticism when component design or coating type may be the prime cause for concern. By examination of design criteria, service conditions, inspection regime, and the coating materials atthe right time in the project span, it should be possible to produce components that perform as required. One cautionary note should be added, however: coating will not necessarily provide a limitless life to the component, although it will provide longevity compared to a similar but uncoated item.
Fatigue Behaviour of Shot Peened Surfaces
Authors: Clancy O. , Ponsonby J. , McCarthy L. , Taylor D.
Published: January 2014

Peening is a technique commonly used to improve fatigue resistance, but it is not always appreciated that excessive peening may be detrimental to fatigue behaviour. The present work demonstrates this effect in three different alloys: a mild steel, stainless steel, and a commercial copper alloy. The dependence of fatigue behaviour on peening intensity is shown to reach a maximum beyond which high intensity peening reduces fatigue life; at very high intensities the fatigue life can be reduced below the unpeened value. This reduction in fatigue life is shown to coincide with an increase in surface roughness, as measured by the parameter Ra, and the onset of a distinct damage mechanism revealed by scanning electron microscopy. The varying effect of peening intensity in the different materials is related to their tensile, fatigue, and wear properties; a model is advanced to explain the observed behaviour, based on the change from an initiation dominated mechanism to a propagation dominated mechanism as peening intensity is increased. A limited number of results is also presented showing the effect of peening time on fatigue behaviour.
Microhardness Measurement as a Quality Control Technique for Thin, Hard Coatings
Authors: Thomas A.
Published: January 2014

A simple method for determining the hardness or thickness of very thin (few micrometre) ceramic coatings is described. The methods employed are demonstrated for hard, thin coatings of titanium nitride, deposited by physical vapour deposition on to high speed steel substrates. A procedure has been formulated, using the microhardness technique, to carry out thickness, hardness, and adhesion quality control checks on coated items.
Wear Mechanisms When Machining Grey Cast Iron with Ceramic Tools
Authors: Brandt G. , Mikus M. , Senesan Z. , Hogmark S.
Published: January 2014

Three cutting tool materials, Coromant ceramic grades CC 620 (based on alumina×zirconia), CC 650 (based on alumina and titanium carbonitride), and CC 680 (based on silicon nitride), were used for evaluation of tool life and wear mechanisms when facing pearlitic flake graphite cast iron without cast skin. Tests were performed at three different cutting speeds, 300, 600, and 800 m min−1, at a feed rate of 0.3 mm rev−1. At 600 m min −1 feed rates of 0·1 and 0·5 mm rev−1 were also used. CC 680 had the highest feed capability and was the only material that could withstand a feed rate of 0·5 mm−1 without fracturing. Tool life was determined by flank wear at all cutting conditions tested except when the highest feed rate was used. CC 620 had the longest tool life and CC 680 the shortest. The main wear mechanism for CC 620 was superficial plastic deformation. In addition, chemical reactions with adhering oxidic layers had influence on the wear rate. CC 650 behaved in a similar way to CC 620. However, the Ti(C, N) phase within CC 650 was worn by diffusion/solution into the work material and also by chemical attack from adhering Fe-Mn silicates. CC 680 was worn almost entirely by a solution/ diffusion wear mechanism. Immersion experiments indicated that composition and thickness of the layers adhering to the flank face could be critical to relative performance ranking of these tool materials. Adherent silicate layers decreased the wear rate of CC 680 due to obstruction of solution/diffusion, whereas the wear rate of alumina based tools increased due to direct dissolution of alumina into the layers. In addition, the wear due to superficial plastic deformation increased as a result of the lower flow stresses of reacted surface layers. Usually, crater wear did not occur due to formation of protective silicate and sulphide layers on the rake face.
Role of X-Ray Diffraction Analysis in Surface Engineering: Investigation of Microstructure of Nitrided Iron and Steels
Authors: Delhez R. , de Keijser Th. H. , Mittemeijer E. J.
Published: January 2014

X-ray diffraction analysis can be very usefully applied in the field of surface engineering, since a depth of a few micrometres only is usually probed. This paper provides an overview of current X-ray diffraction methods for the analysis of surface layers. The treatment is illustrated by examples taken from recent work on nitrided iron and steels. Distinct ways to characterize the effective depth and layer thickness probed are presented. Composition-depth profiles can be measured accurately by tracing the lattice parameter (taking into account the possible presence of stresses) as a function of depth below the surface by successive sublayer removals. A correction for the penetration effect is required and methods for that are presented and demonstrated. The basis of the determination of (macro) stress (the sin2ψ method) is indicated. Attention is paid to the determination of the strain free lattice spacing and (diffraction) elastic constants, to the effect of a concentration-depth profile, and to the comparison of theoretically predicted and experimentally determined strain values. A stress (profile) in a surface layer often originates from the thermal history (cooling after treatment) and the presence of a concentration profile, as is illustrated by examples. Further, the analysis of X-ray diffraction line broadening is discussed. It is shown that nowadays an easily applicable method exists for line profile analysis (the single line Voigt method), allowing the determination of crystallite size and microstrain parameters. As demonstrated by the examples, knowledge of in particular microstrain in conjunction with macrostress is of importance in understanding and predicting material behaviour.
Laser Cladding of Thermal Barrier Coatings
Authors: Vandehaar E. , Malian P. A. , Baldwin M.
Published: January 2014

The feasibility of laser cladding zirconia and alumina thermal barrier coatings on Udimet 700 alloy and AISI 4140 steel substrates was investigated; the objective was to extend the high temperature performance of thermal barrier coatings. Two continuous wave CO2 gas lasers with power levels of 1.2 and 5 kW were employed for cladding. Laser power, powder flowrate, scanning spot size, and travel speed were the major parameters varied during cladding. Zirconia claddings obtained were thin (5–15 μm), dense, hard (800–1700 HV0.2), and crack free, possessing unusually fine microstructures, glassy surfaces, excellent adhesion, and good surface integrity. It was possible to produce thicker claddings, but these tended to crack, delaminate, and chip off from the substrate. The power density was the key process variable that determined the transition from a thicker, cracked coating to a thin, crack free one. The results indicate that a promising approach to generating thicker flawless claddings would be one based upon an improved understanding of the role of power density on the mechanism of melt pool formation. Data are presented on the effects of various laser parameters and coating powder variables on clad thickness and quality.
Optimising Ion Implantation Conditions for Improving Wear, Fatigue, and Fretting Fatigue of Ti-6Ai-4V
Authors: Elder J. E. , Thamburaj R. , Patnaik P. C.
Published: January 2014

A critical evaluation of the effect of ion implantation on wear, fatigue, and fretting fatigue of Ti-6AI-4V is presented for optimising the parameters towards a specific type of property improvement. The analysis presented is based on the extensive results available on the effect of N + or C + implantation on the wear behaviour of Ti-6AI-4 V. In order to obtain the maximum benefit from either of these species the implant conditions and post-implant processing must be such as to ensure second phase precipitation. However, this is not the case for fatigue which is predominantly in the elastic region where solid solution hardening appears to be a sufficient mechanism for increasing the fatigue strength via ion implantation. Improving the fretting fatigue strength via ion implantation is more likely to result from implanting with ions to reduce wear rather than fatigue. Because the mechanisms in unidirectional sliding wear and fretting wear are essentially the same in Ti-6AI-4 V, it appears that ions which improve unidirectional wear resistance should also improve fretting wear. However, variations may arise from the differences between the behaviour of surface oxide layers in unidirectional wear and fretting wear, respectively.
White Layers on Surface of Ground EN24 Steel: 1Microstructure, Composition, Internal Stress, and Corrosion Properties
Authors: Tomlinson W. J. , Blunt L. A. , Spraggett S.
Published: January 2014

The microstructure, composition, internal stress, and corrosion properties of white layers, typically less than 2·5 μm thick, formed on EN24 steel by centreless grinding, have been investigated using microscopy, electron probe analysis, X-ray diffraction, profilometry, and simple immersion tests. No accumulation or depletion of chromium, nickel, molybdenum, phosphorus, carbon, nitrogen, or oxygen occurred over a depth of 100 j1m. The hoop and axial residual stresses at the surface were compressive and about 200 and 600 MN m-2 respectively. The hoop stress changed from compressive to tensile at 2 j1m depth and reached a maximum value of about 850 MN m-2 at a depth of 15 μm. The white layer has an ultrafine microstructure, and the mechanism of formation is consistent with a process of intense thermomechanical plastic deformation. Localised corrosion occurs in solutions containing chloride where the white layer is thin, but as corrosion proceeds it spreads and becomes more general.
Kinetics and Mechanisms of Tin Chemical Vapour Deposition in Ti-CI-H-N System
Authors: Rong Cao Zhi , Sheng Du Yuan , Fang Miao Hue
Published: January 2014

The effects of deposition parameters (temperature, total gas jlowrate, N2/H2 ratio, TiCl4 and HCI concentration) on the deposition rate of TiN were studied in a hot wall reactor. The conditions under which the deposition process is controlled by chemical equilibrium growth, mass transport limited growth, and surface limited growth processes were determined. Mechanisms of TiN chemical vapour deposition (CVD) in the regime of surface control are proposed. When the input partial pressure of hydrogen is 0·666 bar, that of nitrogen < 0·291 bar (i.e. N2/H2 ratio < 0·5), and that of TiCl4 0·145 bar, the rate limiting process is proposed to be the activated adsorption of nitrogen atoms; when N2/H2 = 0·5, the apparent activation energy for CVD of TiN was found to be 120·4 ± 24·2 kJ mol-l and the reactions on the substrate surface TiCl2(a)+H(a) ⇌ TiCI*+HCI(a) TiCI*+H(a) → Ti.HCI(a) Ti.HCI(a)+N(a) → TiN(s)+HCI(a) determine the rate of deposition. Equations for the TiN deposition rate under various conditions have been derived. HCI was proved to be a retarder, but loss of TiN by HCI etching was negligible. An equation for TiN deposition rate in the presence of added HCI was also derived. The equations were found to be in agreement with the experimental data.
SURFACE DEFORMATION BEHAVIOUR OF TiC AND TiN COATED STEELS: 2 SCRATCH RESPONSE AND FRICTION
Authors: Knight J. C. , Page T. F. , Hutchings I. M.
Published: January 2014

Scratch testing using hemispherically tipped diamond styluses of tip radii 100 and 250 Jim has been used to study the surface deformation and frictional behaviour of thin (2–5 μm thick) coatings of TiN and TiC deposited on steels by proprietary CVD and PVD processes. For both the CVD and PVD samples, the coefficient of friction was found to increase with increasing normal load. Analytical evaluation of the data indicates that plastic ploughing appears to dominate the deformation of the coating with adhesion playing little part in the friction process. The dominance of ploughing was confirmed by SEM observations. Further, analysis of the data for scratch tracks contained wholly in the coating showed that, depending on normal load, plastic flow in the surface layers of the substrate due to stresses transmitted through the coating could also significantly influence frictional behaviour.
Conferences
Authors:   none
Published: January 2014

Organised by the Surface Engineering Society (SES) and held at The Institute of Metals, this one day technical meeting reviewed quality control from both the certification/documentation and practical viewpoints.
Effects of Reagents on Electrodischarge Machined Surfaces and Globule Appendages
Authors: Lim L. C. , Wong Y. S. , Lee L. C.
Published: January 2014

The effects of a range of acidic and alkaline reagents on the electrodischarge machined (EDM) surface of AISI D6 tool steel have been investigated. The acidic reagents were found to attack mainly the underlying parent metal at the roots of fine fissures in the recast layer, causing severe localised pitting of the EDM surface. The alkaline reagents, however, reacted strongly with the recast layer, giving rise to an evenly pitted surface. The results indicate that the majority of the globule appendages produced by EDM are fused firmly on to the recast layer. They become an integral part of the surface and cannot be easily dislodged by chemical means.
Fabrication, Microstructure, and Wear of Al-10.6Si Laser Surface Alloyed with Additional Silicon
Authors: Tomlinson W. J. , McAra J. R. , Bransden A. S.
Published: January 2014

A cast Al-10.6 Si alloy has been laser surface alloyed with 9.4, 15, 19, and 35% Si, the coatings have been characterised, and the dry sliding wear against a cast iron surface has been investigated. Except for a few pores, the coatings were relatively uniform in composition, microstructure, and thickness, and had high integrity and continuity with the substrate. The microstructure was very fine, the eutectic composition being displaced to approximately 17% Si. The wear rates of the base alloy, the laser surface melted base alloy, and the laser surface alloyed coatings were similar. The microstructures of the worn pins and the worn cast iron rings are described and discussed. The mechanism of wear is by adhesion, extensive plastic flow, and fracture.
Conferences
Authors:   none
Published: January 2014

The conference, hosted by the South Wales Region of The Institute of Metals, had two streams: ‘Market led developments in iron- and steel making’ and ‘Coatings on metallic substrates’. A total of 120 delegates attended with roughly half in each stream. In his report Mr B. SMITH of British Steel pic reviews the presentations in the coatings section.
Laser Surface Alloying Grey Iron with Cr, Ni, Co, and Co–Cr Coatings
Authors: Tomlinson W. J. , Bransden A. S.
Published: January 2014

A flake graphite grey cast iron has been laser surface alloyed with coatings containing 13-40% Cr, 9-52%Ni, and 26-45% Co. The Ni coatings contained up to 11%Al and the Co coatings contained up to either 2%Al or 25%Cr. The coatings were of high integrity, low porosity, and uniform in composition, microstructures, and hardness. Coatings containing more than 20% Cr reduced considerably the amount of corrosion in 10% nitric acid solution and 3%NaCl solution. A coating containing 20%Cr suppressed completely the substantial corrosion component of wear against a SiC pin in distilled and 3%NaCI waters. The cavitation erosion resistance of the coatings in distilled and salt waters was greatly increased.
The Surface Integrity of a Die Steel after Electrodischarge Machining: 2 Residual Stress Distribution
Authors: Merdan M. A. E. -R. , Arnell R. D.
Published: January 2014

The residual stresses produced in the surface layers of KEA145 (AISI H13) tool steel specimens during electrodischarge machining have been measured by the bending-deflection method. Stress-depth profiles were obtained through progressive removal of material by electropolishing. High residual tensile stresses were found in all specimens, decreasing from a maximum – at the surface for the finishing generator and 20 μm below the surface for the roughing generator – to zero at a depth of about 200 μm. The magnitude of the residual stress increased with pulse energy.
Corrosion Studies on Nickel-Silicon Nitride Composite Coatings
Authors: Ramesh C. S. , Seshadri S. K. , Iyer K. J. L.
Published: January 2014

The electrochemical behaviour of sediment electrodeposited nickel-silicon nitride composite coatings on mild steel has been studied. These composite coatings provide better corrosion resistance in both 3.5% NaCl and 0.5M H2SO4 solution than nickel coatings. The higher the percentage of silicon nitride in the composite, the better is the corrosion resistance. Microstructural studies on these composite coatings have revealed the retention of silicon nitride particles in the coating after corrosion tests, which was indicative of very little or no galvanic corrosion. A reduced tendency to pitting of the composite coatings as compared to nickel coatings was also observed. X-ray analysis of composite coatings exposed to 0.5M H2SO4 revealed the presence of silicon dioxide in them, leading to enhanced passivation of the composite coatings with respect to pure nickel.
Integrated computer control of induction hardening of constant velocity joints
Authors: Kanetake N.
Published: January 2014

The demand for a high level of quality assurance and quality control in the induction hardening of engineering components has led to the design of an integrated control system. This system provides computer control of all the factors involved in heating and cooling during the induction hardening heat treatment cycle. These factors include the preparatory treatments, induction hardening, post-hardening treatments (tempering), testing, inspection, and mechanical transfer of the hardened components. By monitoring the data on all heat treated products, this system provides a reliable quality assurance method for all such induction hardened products. This method of quality assurance of the induction hardening process also provides for energy savings in the heat treatment of automotive parts.
COMPARATIVE STUDY OF PLASMA NITRIDING BEHAVIOUR OF A TYPE 316 STAINLESS STEEL AND A MICROALLOYED STEEL
Authors: Kuppusami P. , Sundararaman D. , Raghunathan V. S.
Published: January 2014

Samples of a type 316 stainless steel and a microalloyed steel were plasma nitrided in the temperature range 673–973 K. Detailed analyses of various nitrides in the nitrided zone have been performed using X -ray diffraction and SEM techniques. An effective cyclic plasma nitriding treatment for type 316 stainless steel has been adopted and its advantages are discussed. The effects of treatment temperature and ion current on the maximum surface hardnesses obtainable for these steels are examined. The effect of the chromium concentration in the stainless steel on the constitution of the nitrided zone is highlighted.
Surface treatments in the automotive industry
Authors:   none
Published: January 2014

This first in a series of technical meetings organised by the Surface Engineering Society (SES) focused on wear problems encountered with automotive components and the solutions surface engineering can offer. Hosted by Eutectic Co. Ltd, it took place at Redditch on 27 May, as GERALD BELL reports.
Characterisation of M42 type high speed steel after laser melting treatment
Authors: Hlawka F. , Marchione T. , Jacura O. , Cornet A.
Published: January 2014

Specimens of an AISI M42 high speed tool steel were austenitised, quenched in a salt bath, and tempered twice. Following this the specimens were moved in front of a focused laser beam to obtain a treatment depth similar to that found under industrial conditions. One series of specimens was examined immediately after the laser treatment, another was subject to four subsequent tempering procedures of 1 h each at 550°C. Following treatment, the quenched but untempered specimens and the tempered material were examined by various means. The effect of laser heating on the solution of carbides, the effect of laser heating and tempering on cutting properties, and possible applications to new cutting tool production technologies are described.
Friction: The ubiquitous coefficient Can it be controlled?
Authors: Over A. , Stevens K.
Published: January 2014

The National Centre of Tribology has been involved in a Department of Trade and Industry-industry cosponsored project investigating the control and reduction of friction through surface engineering. In many industrial areas there are sliding mechanisms operating in dry or marginally lubricated conditions where friction is the main cause of inefficiency. If the friction coefficient can be reduced and maintained at a low level, energy consumption and running costs are lowered. In other components, e.g. brakes and clutches, there is a requirement for controlled high levels of friction. Results for friction obtained from three types of laboratory test, reciprocating sliding, rolling, and combined rolling-sliding, are summarised. The tests were designed to simulate practical industrial situations, including bearings, gears, scuffing conditions, and sliding. The processes investigated cover the whole range of surface engineering, including ion implantation, PVD, CVD, electrochemical and thermochemical diffusion treatments, and sprayed coatings.
IMPROVEMENT OF OXIDATION RESISTANCE OF METALS AND ALLOYS BY HIGH TEMPERATURE COATING AND LASER TREATMENT
Authors: Raman R. K. Singh , Gnanamoorthy J. B.
Published: January 2014

An overview is presented of the phenomenon of high temperature oxidation and its deleterious role in the performance of high temperature components. A brief description of some surface modification techniques (ion implantation, plasma coating, and laser treatment) and their relevance for improving high temperature corrosion properties is also included. An example is discussed where it is described in detail how a suitable combination of plasma coating and laser treatment techniques could be used to confer best protection to metallic substrates for a particular service condition. Mild steel was plasma coated with stainless steel. By giving different laser treatments (by changing the travel speed of the laser beam) a variety of modifications were introduced in thecoating (such as the removal of only the inherent deficiencies, e.g. porosity, and alloying of the substrate material). The plasma coated and the laser treated materials were characterised and oxidation tests were carried out on them in air both in isothermal (973 and 1073 K) and under thermal cycling (between 1073 and 298 K) conditions, along with the uncoated mild steel.As expected, the plasma coating and laser treatments caused marked improvements in the oxidation resistance of the mild steel. A laser treatment that could onlyremove the irregularities of the coating had improved the oxidation resistance of the coating during the isothermal tests, whereas the treatment causing alloying of the substrate and consequent dilution of the coating materials was found to reduce the resistance. However, interestingly, this trend was found to be reversed duringthe long term thermal cycling test. This study has led to an understanding of the applicability of a given laser treatment for a particular service condition, and further, may help in designing coatings and treatments for high temperature components.
CHEMICAL VAPOUR DEPOSITION OF ELECTRICALLY CONDUCTING POLYMERS
Authors: Mohammadi A.
Published: January 2014

For future potential applications of conducting polymers in electronic circuits it would be useful to have fabrication methods which are compatible with semiconductor device technology. The existing electrochemical or wet chemical methods of making electrically conducting polymer films may be difficult to apply inthis context. Therefore, it has been decided to study the possibility of preparing conducting polymer films from the gas phase, in a manner similar to the chemical vapour deposition (CVD) method. Electrically conducting polypyrrole films have been synthesised in two ways: from the vapour phase using hydrogen peroxide, hydrochloric acid, and pyrrole monomers and from polypyrrole doped with ferric chloride using a CVDtechnique.
HARDNESS CHARACTERISATION OF THIN CARBON COATINGS
Authors: Dahm K. L. , Ferguson W. G. , Murakami R. , Dearnley P. A.
Published: January 2014

Microhardness indentations nonnal to the surface of thin coatings usually result in deformation of bothcoating and substrate. Such measurelnents lead to a ‘composite’ hardness nUlnber which is a function of the properties of the coating and substrate, the ratio of the depth of indentation to the coating thickness, and the indenter geometry. In order to determine the hardness of the coating it is necessary to find some way of separating the contributions from the coating and substrate which comprise the composite hardness. In the current investigation an attempt was made to measure the hardness of thin diamondlike carbon (a-C :H) coatings deposited by plasma assisted chemical vapour deposition (PACVD) using the ‘area law of mixtures rule’ proposed by Jönsson and Hogmark, thus enabling the quantification of both contributions. Composite and substrate hardness values were obtained for indentation loads ranging from 100 to 1000 g. In all cases a linear relationship was found betweenhardness and the reciprocal of the indentation diagonal. These correlations enabled the load invariant hardness to be determined for all the carbon coatings. With the exception of one sample, the Vickers hardness of the carbon coatings was determined to reside within the range 1900–2300 kg lmm–2. The carbon coatings were also briefly studied using X-ray diffraction (XRD) and Raman spectroscopy. For all samples the XRD spectra obtained showed a complete absence of long range crystallographic structure. The Raman spectra obtained were the same for all samples and similar to the spectra obtained elsewhere for a-C: H coatings deposited by PACVD, and indicate that there is both graphitic (Sp2) and diamond (Sp3) bonding present in the coatings.
CONTACT MECHANICS OF ENGINEERING SURFACES: STATE OF THE ART
Authors: Mao K. , Sun Y. , Bell T.
Published: January 2014

Significant progress has been made in the study of contact mechanics of engineering surfaces, particularly layered surfaces, in the past decade. This mainly involves the removal of the assumptions in the Hertztheory. The application of numerical techniques including the integral transform and finite element methods has successfully solved many contact problems which are difficult with analytical solutions. The present paper reviews the recent developments in contactmechanics of engineering surfaces, with emphasis on the layered surfaces where a coating or several coatings with varying mechanical properties are produced on top of the substrate by means of surface engineering. The developments in non-layered contact theories are first briefly discussed, followed by detailed discussion of the layered surface contact theories which have been developed on this basis. Finally, further work which is needed in the near future concerning layered surface contacts is proposed.
Application of electric arc spraying technique to enhance corrosion resistance of steel structures on ships
Authors: Xu B. , Shining M. , Wang J.
Published: January 2014

Steel structures on ships operate in hostile environments and can be subject to severe corrosion. Composite coatings consisting of aluminium arc sprayed nd organic layers can effectively increase the corrosion lifetime of such structures. The composite layer developed consists of an electric arc sprayed aluminium layer followed by a layer of organic paint to seal the aluminium coating, followed by a layer of a conventional ship's paint.
Method of Measuring Nitrided Case Depth for Iron and Steel
Authors:   none
Published: January 2014

The following is an English translation of Japanese Industrial Standard G0562, compiled on behalf of the Divisional Council on Iron and Steel, which is reproduced as an information service to SE readers. Dr Norio Kanetake, a member of the SE Editorial Panel, chaired the committee most closely involved with the preparation of this standard.