Adhesive and abrasive wear behaviour of TiC alloyed,sintered, austenitic stainless steels

Abstract

This study examines abrasive and adhesive wear behaviour of austenitic stainless steel and its TiC alloyed composite produced through powder metallurgy technique. Abrasive wear tests have been carried out using a pin on disc wear tester under loads of 10, 20 and 30 N. For adhesive wear tests, a block on ring wear tester has been used under loads of 20, 40, 60 and 80 N. A possible correlation between the hardness, microstructure and wear behaviour of the samples has been investigated. The abrasive wear tests have revealed that the highest rate of mass loss occurred in the austenitic matrix stainless steel sample; also, mass losses decreased with an increased rate of reinforcing material in the composite. In adhesive wear tests, interparticle spacing developed from severe wear and extreme plastic deformation under heavy loads; however, at low loads, oxidation type wear was shown to be dominant.     

Wear mechanisms in electroless nickel coatings

Electroless nickel coatings are susceptible to severe adhesive wear against plain carbon steel under dry sliding contact, because the low interfacial and high surface free energies of this material combination produce highly compatible surfaces. Controlled heat treatment eliminates severe wear by inducing crystallization of amorphous nickel to Ni₃P, which is incompatible with steel. Electroplating the counterface with chromium also eliminates severe adhesive wear owing to the efficient barrier properties of its surface oxide but a stainless steel counterface exacerbates the problem because of its single-phase microstructure and the low durability of its oxide film. The reciprocating diamond scratch test gives a different ranking order of wear rate from the Falex, pin-on-flat and Taber tests, because of its dependence on fracture toughness as the dominant material parameter rather than adhesive transfer. Wear mechanisms observed in the investigation include adhesive transfer, oxidation, three-body abrasion, micromachining, plastic deformation and delamination. In general, no correlation is found between wear rate and hardness; this is primarily because of changes in the mechanism of wear effected by processing, counterface materials or sliding conditions.     

Abrasive wear resistance of some commercial abrasion resistant steels evaluated by laboratory test methods

The aim of the present study is to evaluate the abrasive wear resistance of some potential abrasion resistant steels exposed to different types of abrasive wear contact conditions typical of mining and transportation applications. The steels investigated, include a ferritic stainless steel, a medium alloyed ferritic carbon steel and a medium alloyed martensitic carbon steel.The abrasive wear resistance of the steels was evaluated using two different laboratory test methods, i.e. pin-on-disc testing and paddle wear testing that expose the materials to sliding abrasion and impact abrasion, respectively. All tests were performed under dry conditions in air at room temperature. In order to evaluate the tribological response of the different steels post-test characterization of the worn surfaces were performed using optical surface profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. Besides, characterization of the wear induced sub-surface microstructure was performed using optical microscopy.The results show that depending on the abrasive conditions a combination of high hardness and toughness (fracture strain) is of importance in order to obtain a high wear resistance. In the pin-on-disc test (i.e. in sliding abrasion) these properties seem to be controlled by the as-rolled microstructure of the steels although a thin triboinduced sub-surface layer (5–10 μm in thickness) may influence the results. In contrast, in the paddle wear test (i.e. in impact abrasion), resulting in higher forces acting perpendicular to the surface by impacting stones, these properties are definitely controlled by the properties of the active sub-surface layer which also contains small imbedded stone fragments.     

Tribological Properties of Double-Glow Plasma Surface Niobizing on Low-Carbon Steel

The niobized layer was formed on Q235 low-carbon steel by double-glow plasma surface niobizing to improve its wear resistance. The microstructure, phase composition, and microhardness were determined. The friction and wear properties of the niobized samples and the untreated alloys were tested on a ball-on-disk tribometer by rubbing against GCr15 and silicon nitride (Si₃N₄) balls at room temperature and 400°C, respectively. The results indicated that the alloyed layer that contained a sediment layer and diffusion layer is about 35 μm in thickness, metallurgically adhered to the base metal. Niobium content was gradually decreased along the depth direction from the surface, which was similar to the change in the microhardness. The alloying layer mainly consisted of Nb, Fe₂Nb, and FeNb phases. Under unlubricated sliding conditions, the friction coefficients and the specific wear rates were lower than those of the untreated carbon steel at room and high temperatures. The wear mechanism of the niobized specimen at room temperature is dominated by slightly abrasive wear, whereas the predominant wear mechanism is abrasive wear and fatigue delamination at high temperature.     

Abrasive and Adhesive Wear Behavior of Arc-Evaporated Al<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Cr<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>N Hard Coatings

During the last decade, the usage of difficult-to-machine materials such as austenitic stainless steels has increased continuously in various industrial applications. Tools such as blind hole taps, punches, or deep drawing molds are often exposed to severe wear while machining/forming these materials, mainly due to excessive adhesion and material transfer. On combination with abrasive wear due to work-hardened wear debris, tool lifetime in these applications is often limited. In this study, ball-on-disc experiments were carried out with arc-evaporated AlCrN coatings with different Al/(Al + Cr) ratios against Al₂O₃ and austenitic stainless steel balls in ambient atmosphere. Test temperatures of 25, 500, and 700°C were chosen for the hard Al₂O₃ balls simulating severe abrasive loads, whereas 25, 150, and 250°C were used for the softer stainless steel material to evaluate the adhesive wear behavior. Characterization of the wear tracks was done by scanning electron microscopy in combination with energy-dispersive X-ray analysis and optical profilometry. The best abrasive wear resistance during testing against Al₂O₃ was observed for the coating with the highest Al content. In the case of the austenitic stainless steel balls, sticking of the ball material to the coating surface was the dominating wear mechanism. The influence of test temperature, chemical composition, and surface roughness was studied in detail.     

Wear behaviour of hardfaced Fe-Cr-C alloy and austenitic steel under 2-body and 3-body conditions at elevated temperature

Fe-based hardfacing alloys are widely used to protect machinery equipment exposed to different loading situations where abrasives play a dominant role in restricting lifetime of tools. Wear at elevated temperatures is superposed by the effect of oxidation of the wearing surface. In view of the above, two hardfacing alloys based on Fe-Cr-C incorporating Nb, Mo and B to ensure improved performances at elevated temperature were deposited onto mild steel under optimised gas metal arc welding (GMAW) condition. 2-body erosive wear behaviour was evaluated from room temperature up to 650 °C under 30° and 90° impact angle. For 3-body impact/abrasion conditions tests were done with a specially designed cyclic impact abrasion tester (CIAT) at room temperature and 600 °C. The wear behaviour of the hardfacings was compared with austenitic stainless steel. Results indicate that 2-body erosive wear rate of the hardfacing increases with test temperature and with increase in impact angle, whereas wear behaviour of the austenitic stainless steel is non-sensitive to the testing temperature at normal impact. In 3-body impact abrasion testing similar behaviour can be seen; cyclic tests in CIAT at enhanced temperatures result in breaking of coarse carbides, whereas wear mechanisms of the austenitic steel result in massive abrasion and formation of a mechanically mixed layer (MML).     

氮对316L不锈钢焊缝力学性能的影响

为研究氮对316L不锈钢焊缝力学性能的影响,采用不同氮质量分数的三种自行研制的焊丝,分别对几组316L不锈钢试板进行钨极氩弧焊(Tungsten inert gas,TIG)焊接,焊后通过金相显微镜和扫描电镜分别观察并分析相应的焊缝组织,采用磁性法测量焊缝的铁素体的质量分数,并对焊缝的拉伸性能、冲击性能等力学性能进行测试。从氮的固溶和焊缝组织的变化等方面综合分析氮对316L不锈钢焊缝力学性能的影响。结果发现,随着氮质量分数的增加,焊缝奥氏体组织明显粗化,铁素体质量分数呈下降趋势;焊缝强度有所提高,且氮质量分数由0.011%增加到0.081%时焊缝强度的平均提高程度小于氮质量分数由0.081%增加到0.10%时焊缝强度的平均提高程度;另外,焊缝的塑性及冲击韧度均有所降低。     

Influence of work material proof stress and tool steel microstructure on galling initiation and critical contact pressure

EN 1.4301 (austenitic), EN 1.4509 (ferritic), EN 1.4162 (duplex) and EN 1.4310 C1000 (metastable austenitic) stainless steels were tested in lubricated sliding against an ingot cast EN X153WCrMoV12 and powder metallurgy nitrogen alloyed Uddeholm Vancron 40 tool steels to reveal critical to galling contact pressure, P_cr. The calculated P_cr were higher for steels with higher strength. At P>P_cr, due to plastic flow of sheet material, the tool is damaged substantially and wear-induced matrix damage causes rapid galling initiation. At P<P_cr, galling was not observed. The powder metallurgy tool steel was more resistant to galling against all tested stainless steels. Better performance was associated with fine and homogeneously distributed hard phases preventing intensive wear of the tool steel matrix.     

Corrosion and wear resistance characteristics of NiCr coating by laser alloying with powder feeding on grey iron liner

To reduce the mixed fuel induced excessive wear of the cast iron engine cylinder liners, research on laser alloying of NiCr alloy with powder feeding was performed to locally change both the composition and the microstructure of the liner. The research indicated that laser alloying of 75Ni25Cr on grey cast iron liner demonstrates sound alloying layers free of cracks and porosities. The microstructure of the alloyed layer is composed of pre-eutectic austenite and ledeburite. The alloying element Ni is mainly located in the austenite, while Cr is mainly in cementite. The average hardness is HV_0.2500. The corrosion resistance of the alloyed layers in diluted H₂SO₄ solution and NaOH solution is dramatically improved compared to the grey cast iron. The relative wear resistance of the laser-alloyed 75Ni25Cr layer is 4.34 times of that of the grey cast iron. The improvements on the corrosion and wear resistance of the cast iron are attributed to the composition and microstructure change by laser alloying of 75Ni25Cr. Laser alloying can be a good solution to improve wear and corrosion resistance of the grey iron liners in mixed fuel environment.     

Experimental investigation on deformation and wear of WC tool during friction stir welding (FSW) of stainless steel

In this paper, the effect of friction stir welding (FSW) parameters on wear and deformation behavior of tungsten carbide (WC) tool employed in the welding of AISI 304 austenitic stainless steel (SS) is reported. In addition, the wear and deformation of the tool are also characterized. Three FSW parameters, namely shoulder diameter, tool rpm, and traverse speed each at three levels were considered. Experiments were performed as per Taguchi’s L₉ orthogonal array to investigate the effect of these parameters on wear and plastic deformation of the tool. Wear at the pin root and bottom face of the pin attributed to diffusion and attrition mechanisms, respectively, were observed. Significant deformation of the tool was also observed during welding which caused bulging of the shoulder with an increased cone angle of the pin.     

A review of the performance of engineering materials under prevalent tribological and wear situations in South African industries

The wear of materials used on machinery operating in a wide range of industrial situations such as mining, energy production and agriculture can cause serious inefficiencies, sudden breakdowns and consequential financial losses. Our work over two decades has concerned industrial problems encountered in South African industry, and laboratory simulations of abrasion, abrasion plus corrosion, adhesive wear, impact wear, cavitation, solid particle erosion and erosion plus corrosion situations have been successfully undertaken. Materials investigated include plain carbon and alloy steel, stainless steels, aluminium alloys, cast irons, tungsten carbide cermets, ceramics, polymers, composites and various surface treated and coated materials. The paper reviews the investigations carried out in our laboratories and conclusions we have made.     

Investigating the change in wear behaviour of a tool steel after surface melting and gaseous alloying

In this study it is shown that surface melting in the presence of a reactive gas can be used as a method of changing the tribological properties of a hot forging die steel. A H13 tool steel surface was melted in the presence of a gaseous shield of pure argon, nitrogen, carbon dioxide and a mixture of 80% carbon dioxide–20% argon. Microhardness profile measurements and metallographic examination was used to study the changes in wear behaviour after surface modification. The results indicate a significant increase in surface hardness after the melting and gaseous alloying process with the most wear resistant surfaces produced under a shield of CO₂ and CO₂–Ar gases. This was attributed to the formation of a fine dendritic microstructure consisting of chromium–vanadium carbides. The presence of these hard phases in the surface reduce the degree of plastic deformation and wear by adhesive mechanisms.     

介稳奥氏体锰钢耐冲击磨粒磨损性能及磨面组织

利用冲击磨粒磨损试验结合扫描电镜、透射电镜和穆斯堡尔谱等分析手段研究了介稳奥氏体锰钢的耐磨性和磨损机制。结果表明,介稳奥氏体锰钢在某一冲击功下具有最佳耐磨性。在磨损过程中磨面诱发生产两类马氏体,无碳马氏体和合金马氏体。最耐磨时的磨面组织为合金奥氏体和无碳马氏体的混合组织。     

Modeling of Microstructures and Analysis of Abrasive Wear of Arc-Welded Hadfield Steel

The results of analytical and experimental studies of the microstructures of the welded layers of the Hadfield steel (basic and alloyed with Cr, Ni, Mo, and B) have been presented. Layers additionally reinforced by coarse-grained tungsten carbide have also been studied. It has been shown that an austenitic microstructure prevails in the base and alloyed Hadfield steel. Analytical investigations of the coating structure shows the formation of 95–99% austenite and, in the case of the reinforced phase, the austenite content is 50–56% of the material (the remainder is tungsten carbide, cementite, etc.). It has been found that the presence of the strengthening phase of coarse-grained tungsten carbide, which reduces the amount of austenite under the conditions of abrasive wear, may exert both positive and negative impact on wear.     

Wear behaviour of some low alloyed steels under combined impact/abrasion contact conditions

The wear behaviour of some low alloyed steels has been investigated using a laboratory impeller–tumbler wear test equipment in which the steel samples are worn by angular granite particles under combined impact/abrasion wear contact conditions. The wear of the steels was evaluated by weight loss of the steel samples while the wear mechanisms of the steels were investigated by post-test light optical microscopy (LOM), scanning electron microscopy and energy dispersive X-ray analysis. The worn steel surfaces display a very rough surface topography with pronounced craters and distinct grooves caused by high and low angle impacts, i.e. abrasive wear, respectively. Besides, fragments of embedded granite particles are frequently observed in the worn surface of the steels. The wear of the steels tends to decrease with increasing steel hardness. However, instead of using the bulk hardness value the hardness of the worn/plastically deformed surface layer should be used when modelling the wear resistance. Further, the wear resistance of the steels was found to be dependent on the microstructure and chemical composition. Steels with similar type of microstructure show a linear decrease in weight loss with decreasing grain size and increasing carbon content.     

Microstructure and Tribological Properties of a HfB<Subscript>2</Subscript>-Containing Ni-Based Composite Coating Produced on a Pure Ti Substrate by Laser Cladding

A HfB₂-containing Ni-based composite coating was fabricated on Ti substrates by laser cladding, and its microstructure and tribological properties were evaluated during sliding against an AISI-52100 steel ball at different normal loads and sliding speeds. The morphologies of the worn surfaces were analyzed by scanning electron microscopy (SEM) and three-dimensional non-contact surface mapping. The results show that wear resistance of the pure Ti substrate and NiCrBSi coating greatly increased after laser cladding of the HfB₂-containing composite coating due to the formation of hard phases in the composite coating. The pure Ti substrate sliding against the AISI-52100 counterpart ball at room temperature displayed predominantly adhesive wear, abrasive wear, and severe plastic deformation, while the HfB₂-containing composite coating showed only mild abrasive wear and adhesive wear under the same conditions.     

Abrasive wear behaviour of sintered composite austenitic stainless steels having γ-Fe and M23C6 phases

Abstract

Using powder metallurgy, composites of austenitic stainless steel were produced along with unreinforced stainless steel mixed with titanium, cobalt and molybdenum particles. Wear resistance of the materials was measured by a two body pin on disc wear tester. SiC abrasive papers of 80 and 220 mesh sizes were used as abrasive media. Wear tests were performed under loads of 10, 20 and 30 N at room temperature. The abrasive wear measurements showed that the softer, unreinforced austenitic stainless steel exhibited higher mass loss than the composites. Furthermore, the abrasive wear resistance of the reinforced austenitic stainless steel composites increased with increasing FeTi, FeMo, or Co volume content. In addition, the wear rate against the 80 grade SiC abrasive paper increased more than against the 220 grade SiC abrasive paper.     

Study on tribological properties of Al2O3 ceramics/1Cr18Ni9Ti stainless steel rubbing pairs in H2O2 solutions

The tribological properties of (Al₂O₃) ceramics/1Cr18Ni9Ti stainless steel rubbing pairs were investigated using a MMW‐1 tribo‐tester under pure water and different concentrations of hydrogen peroxide (H₂O₂) solutions. A comparison analysis of the friction coefficient, wear mass loss and worn surface topographies was conducted. The wear mass loss of the 1Cr18Ni9Ti stainless steel ring sample in all H₂O₂ solutions was greater than that in pure water. The wear mass loss was the highest in 70% H₂O₂ solution. The comprehensive analysis showed that the main wear mechanisms between the Al₂O₃ ceramics/1Cr18Ni9Ti stainless steel rubbing pairs were severe adhesive, abrasive and ploughing wear in the H₂O₂ solutions. It is believed that the knowledge gained in this study will provide the theoretical data and guide for the optimisation of the rubbing pairs in the H₂O₂ solutions to be used for the lubrication of some moving parts in the propulsion system of the launch vehicle. Copyright © 2010 John Wiley & Sons, Ltd.     

Evolution of friction-induced microstructure of SUS 304 meta-stable austenitic stainless steel and its influence on wear behavior

The microstructure evolution of the worn surface and sub-surface layer of SUS 304 austenitic stainless steel (ASS) disc against Al₂O₃ ceramic ball were studied on the basis of the tribological behaviors in the tests performed using a Cameron-Plint TE67 pin-on-disc tester. The microstructure after friction test was observed by optical and scanning electron microscope. The possible phase transformation of meta-stable austenite to martensite was detected by X-ray diffractometer. Results showed that friction-induced deformation led to finer grain at the subsurface beneath the worn surface. Furthermore, white layer was observed on some worn surface layers after higher normal loads. Transformed martensite from the austenite appeared on the worn surface under both low and high normal-loading conditions. Absence of transformed martensite was detected at the site about 25 μm below the worn surface although the grains at the site were still intensive and fine. In addition, the specific wear rate of SUS 304 stainless steel specimens was measured, and the possible reasons affecting the wear behavior were analyzed and discussed.     

The microstructure and wear behaviour of friction stir processed AISI 430 ferritic stainless steel

ABSTRACT

The microstructure and wear behavior of Friction Stir Processed (FSPed) AISI 430 ferritic stainless steel were analyzed in the present study. FSP was performed with a tool rotation and advancing speeds of 1400?rpm 16?mm/min respectively by employing a tungsten carbide tool. The FSPed microstructure consisted of a mixture of ferrite and martensite. After FSP, microhardness increased with respect to that of the as-received material. The wear resistance of the FS processed material was significantly enhanced if compared to that of the as-received substrate. According to the SEM analyses of the worn surfaces and wear debris, a combination of adhesive wear and delamination was observed in the case of the base metal. The wear mechanism shifted to mild adhesive wear after FSP. The superior wear resistance of the FS processed AISI 430 steel was attributed to the pronounced grain refinement and to martensite formation in the stir zone.