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.     

On the comparison of the abrasive wear behavior of aluminum alloyed and standard Hadfield steels

The abrasive wear behaviors of aluminum alloyed Hadfield steel at the high and low stress wear conditions were studied and compared with non-Al alloyed Hadfield steel. The wear tests were done with the pin on disc method using the abrasive wheel. The main parameters such as alloy compositions, normal load, sliding speed and sliding distance were evaluated. It is shown that at the low stress condition, the aluminum alloyed Hadfield steel has higher wear resistance than the non-Al alloyed Hadfield steel. But at the high stress wear conditions, the non-Al alloyed Hadfield steel is more resistant than the Al alloyed.     

Impact wear resistance of WC/Hadfield steel composite and its interfacial characteristics

A composite coating of WC/Hadfield steel was fabricated through centrifugal casting process to improve the impact wear resistance of Hadfield steel under the conditions of low or medium impact energy. The interfacial structure between WC ceramic particle and the steel matrix was analyzed with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The impact wear tests at different impact energy were carried out on a MLD-10 type impact wear rig to investigate the wear-resistant properties of three kinds of composites with different WC particle sizes. For comparison, the wear tests of Hadfield steel were also carried out under the same conditions. The results show that WC particles are partially dissolved in the steel during centrifugal casting. The elements W, C and Fe in steel react to form new carbides such as Fe₃W₃C or M₂₃C₆, which precipitate around former WC particles forming fine particles during subsequent solidification. So the interface between WC particles and Hadfield steel matrix is a strong metallurgical bonding. The composite reinforced with smaller WC particles has better impact wear resistance than that of Hadfield steel regardless of impact energy level. Whereas, the composite reinforced with larger WC particles has better impact wear resistance property than that of Hadfield steel when the impact energy is small but an opposite result is gained when the impact energy is higher. So, it is very essential to choose suitable size of WC particles as reinforcement in Hadfield steel to make the composite material more durable in the service conditions.     

Wear of cast chromium steels with TiC reinforcement

Wear resistance of a series of new titanium carbide reinforced cast chromium steels was investigated under various wear conditions. The steels which were melted in a vacuum induction furnace contained 12 Cr, 3–5 Ti, 1–2 C in weight percent. Microstructure of these materials was characterized using scanning electron microscopy, light optical microscopy, and X-ray diffraction. Microstructure of steels consisted of TiC phase dispersed in a martensitic matrix. High-stress and low-stress abrasion tests, and an erosion test, were utilized to understand the wear behavior of these materials under different environments. The steels were tested in as-cast and heat treated conditions. Wear rates of the cast Cr/TiC steels were compared to those of an AISI type 440C steel and P/M composites reinforced with TiC.     

Performance of cryogenically treated tungsten carbide tools in milling operations

This paper describes a study on the effects of cryogenic treatment of tungsten carbide. Cryogenic treatment has been acknowledged by some as a means of extending the tool life of many cutting tool materials, but little is known about the mechanism behind it. Thus far, the only few detailed studies conducted pertain to the cryogenic treatment of tool steels. However, tungsten carbide cutting tools are now in common use in industry. This paper primarily reports and analyses the differences in tool performance between cryogenically treated and untreated tungsten carbide tool inserts during the high-speed milling of medium carbon steel. In addition to dry cutting, machining with coolant was also tested. From the results, it can be seen that cryogenically treated tools exhibit better tool wear resistance than untreated ones. Also, it is evident that the application of coolant during cutting helps to reduce tool wear experienced by the cryogenically treated tools even further. In addition, cryogenically treated tools are found to perform best under a particular set of cutting conditions.     

The wear of martensitic stainless steel against tungsten carbide at temperatures up to 500 °C

The bearings in air motors of modern jet aircraft engines must operate dry in hostile conditions at temperatures up to 500 °C. One of the few metallurgical combinations which can function efficiently under these conditions is martensitic stainless steel on tungsten carbide. The work described was initiated to isolate the wear mechanism of such steels in contact with tungsten carbide at elevated temperatures. Experiments were carried out for pure sliding conditions (pin-on-disk experiments) and for rolling-sliding angular-contact bearings such as those used in practice. Wear rates were measured for both configurations for a series of loads, speeds and surface temperatures and extensive X-ray diffraction analyses were carried out on wear debris and on worn surfaces. Three distinct mechanisms of wear were established and found to be present in both configurations. These involve oxidation and abrasive wear at lower temperatures but become heavily dependent on material transfer as temperature increases. It is proposed from the results that the pin-on-disk experiments may be useful as a screening test for the selection of materials without the considerable cost of producing one-off angular-contact components. More evidence from other materials is, however, necessary to establish the validity of the test.     

Wear resistance of steels under wet-abrasive erosion conditions

The wear resistance of 22 different steels with various heat treatments in a silica sand slurry was studied. Two types of slurry were used, a fresh sharp grain slurry, and a worn dull grain slurry.In the sharp grain slurry the wear resistance increased with the hardness of the steel. In the dull grain slurry the wear resistance was divided into two major groups. For the steels containing little or no chromium the wear resistance decreased slightly with an increase in the hardness of the steel. For steels with a higher chromium content the wear resistance was three times that of the steels with a low chromium content. The latter behaviour was thought to be the result of the abrasives removing only the products of corrosion and not the steel substrate.The role of corrosion was confirmed by testing three steels in the two types of slurry test, with and without a corrosion inhibitor.Hadfield manganese steel has poor wear resistance in both the sharp and the dull grain slurry. It is actually slightly worse in the dull grain slurry.     

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.     

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.     

The effects of work material on tool wear

Wear maps showing the wear behaviour of titanium carbide (TiC)-coated cemented carbide tools during dry turning of various types of steel have been presented in earlier studies. The maps have demonstrated that tool wear rates vary with cutting speeds and feed rates used. They have also shown that there is a range of cutting conditions, called the safety zone, within which tool wear rates are the lowest. This paper further examines, using the wear mapping methodology, the effects of different grades of steel workpieces on the wear of TiC-coated carbide tools. Wear maps constructed for the machining of AISI 1045 and 4340 steels show that flank wear is generally more severe when machining the AISI 4340 grade, especially at high cutting speeds and feed rates. Nevertheless, the contour and location of the safety zone on the wear maps for both grades of steels correspond to that revealed in previous work on general steel grades.     

Effect of Carbides on Wear Characterization of High-Alloy Steels under High-Stress Rolling–Sliding Condition

This article describes the wear characterizations of high-speed steel composed of vanadium carbide and high-chromium cast iron composed of chromium carbide. These metals were studied under rolling–sliding conditions with a sliding ratio of 10% using a self-made ring–ring wear testing machine. The fine microstructure of carbides and failure behaviors were analyzed by scanning electron microscopy and high-resolution electron microscopy. The results showed that carbide significantly affected the wear properties and failure behaviors of metals. The relative wear resistance of high-speed steel reinforced by vanadium carbides was twice that of high chromium cast iron composed of chromium carbides. Chromium carbide was characterized by a stacking fault substructure, and slips occurred in chromium carbide under high-stress contact, resulting in crack formation. Vanadium carbide was reinforced and pinned by large amounts of nanoparticles, which prevented its dislocation under high-stress rolling–sliding conditions, thereby effectively resisting crack initiation. Furthermore, the (200) lattice plane of vanadium carbide is coherent with the (111) lattice plane of austenite, preventing cracks from forming at the interface of the vanadium–carbide matrix. The morphology and hardness of vanadium carbide also contributed to the excellent wear property of high-speed steel.     

Improvement of ductile iron wear resistance through local surface reinforcement

Ductile iron (DI) or spheroidal graphite cast iron is an attractive ferrous material being widely used due to its combination of low cost and good combination of strength, toughness and fatigue endurance. However, under severe service conditions, experienced in seashore, earth-moving and mining applications the performance and reliability of DI are limited due to its poor wear resistance. Wear resistance of DI can be improved through different heat treatment and surface engineering techniques, each having some limitations and drawbacks. Recently, a new method called OPTICA has been introduced, which through local reinforcement with inserts improves wear resistance of ductile iron without compromising other properties.Results of the present investigation show that tribological properties of ductile iron can be greatly improved by local surface reinforcement. Through the formation of carbides a hard transition or functional gradient zone is formed around the inserts, which then carries the load and improves wear resistance of ductile iron, at the same time maintaining low friction. However, wear resistance of reinforced ductile iron can be improved even further, using proper austempering process. If austempered at 350 °C, wear resistance of ductile iron will become comparable or even better than reference Hadfield grade steel. In this paper reinforced or reinforcement refers to locally alloyed material in preselected zones of the casted object if not specified otherwise.     

GCr15及G20CrNi2Mo轴承钢高温润滑条件下摩擦磨损性能

为了探究轴承钢在高温润滑条件下的摩擦磨损性能,采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、洛氏硬度计等对GCr15高碳轴承钢和G20CrNi2Mo渗碳轴承钢组织、物相及硬度进行了表征,利用QG-700型气氛高温摩擦磨损试验机研究轴承钢材料不同条件下的高温润滑摩擦磨损性能,并分析其磨损机制.结果表明:2种轴承钢...     

Mapping the role of Cr content in dry sliding of steels: Comparison between maps for material and counterface

In this work, a study of the wear transition regimes was carried out for a pin-on-disk sliding couple, involving two steels of different hardness and Cr contents. Dry sliding wear behaviour of the more highly alloyed stainless steel was dominated by adhesive wear and tribo-oxidation at relatively low sliding speeds and by mixed and adhesive wear at high speeds and loads. In contrast, oxidative wear was more predominant for the lower alloyed steel. The individual wear maps generated for the individual components i.e. material and counterface are discussed in the context of the wear mechanisms observed in the tribological contact.     

Investigation of abrasive wear resistance and wear mechanism of composite alloys

The abrasive wear resistance of composite alloys comprising hard tungsten carbide and soft CuNiMn matrix under different wear conditions has been investigated and compared with CrMo cast iron. It was found that Yz-composite alloy with hard cast angular tungsten carbide has greater wear resistance than CrMo cast iron under two-body wear conditions, but lower resistance than Cr-Mo cast iron under three-body wear conditions. It was found that under three-body wear conditions selective wear of the matrix and digging or fragmentation of tungsten carbide particles dominate in Yz-composite alloy, and microcutting and deformed ploughing is dominant under two-body wear conditions. The abrasive wear resistance of composite alloys under two-body wear condition is independent of bulk hardness, but is closely related to the microhardness of tungsten carbide.     

Determination of the wear coefficient of tungsten carbide by a turning operation

Turning operation was carried out, by using tungsten carbide inserts and a CNC lathe on low carbon and medium carbon steels, to determine the wear coefficient of tungsten carbide. The nominal (starting) workpiece diameter was 118 mm and the cutting speeds used were 70, 100, 130 and 160 m/min. The thrust and turning forces acting on the insert were measured from a force dynamometer. The turning distance was obtained from the diameter of the workpiece and its rotational speed. Calculations were made on the flank and crater wear volumes using an OMIS machine. The average wear coefficient of tungsten carbide was found to be 10×10⁻⁸. This value was obtained by averaging the wear coefficient values determined from the flank wear on turning both low and medium carbon steels; as well as from a statistical analysis of the wear coefficient values obtained between a turning temperature of 453 and 664°C. As compared with the average value of 106×10⁻⁸ obtained from the moving pin-on-disc test conducted earlier, it is lower by about one order of magnitude. It is suggested that the high turning temperature at the tool-chip interface may have lowered the hardness of the work materials during the turning operation to give the lower wear coefficient values.     

A scanning electron microscope study of attrition wear in tungsten carbide taper pin reamers

The wear of tungsten carbide taper pin reamers used to ream holes in a composite structure of aluminium alloy plate overlaying a plate of ultra-high strength steel was examined under the scanning electron microscope. The predominant process of wear was by attrition, which involved the mechanical detachment of individual or groups of tungsten carbide grains from the reamers by both the swarf and workpiece material.This process of attrition wear was initiated by the removal of the cobalt binder phase, resulting in the undermining and subsequent removal of tungsten carbide grains. A mechanism is described for explaining how the cobalt binder phase is initially removed, and the means by which tungsten carbide grains are then removed are discussed. Consequent on the removal of tungsten carbide grains some cobalt binder phase attached to these grains is also removed, and this subsequently becomes an important mechanism of cobalt binder phase removal.     

Study of the Tribotechnical Properties of a Cutting Tool Made of Sintered Powder Tool Materials

The research results on the wear of cutting tools made by sintering high-speed steel powders have been presented. It has been shown that powder tool materials based on high-speed steel additionally alloyed with titanium carbide have high wear resistance and can be classified as a new class of self-organized tool materials. As has been shown by the research, the wear resistance of these tools is 2–3.5 times higher than the wear resistance of standard high-speed steel tools.     

Determination of the efficiency of high-entropy cutting tool materials

Modern approaches to determination of the durability of cutting tool materials taking into account the effect of their entropy, Thermo-EMF, and the functional relationships between them are presented. It is confirmed that the tribological properties of complex alloyed high-speed steels and experimental cemented carbide hard alloys (ECCs) with modified cobalt binder as high-entropy materials can be improved. The results of a study of wear resistance, oxidation resistance, and optimum cutting conditions of ECCs are presented.     

钴基合金-碳化钨复合涂层材料耐磨性能的研究

采用真空熔烧法制得钴基合金—碳化钨复合涂层材料,借助扫描电子显微镜、X射线衍射仪等先进的测试手段对涂层的组织结构和表面形貌进行观察分析。应用盘销式摩擦磨损试验机对不同碳化钨质量分数的复合涂层材料和淬火态45钢进行了磨损试验。结果表明:在相同试验条件下,复合涂层的耐磨性显著高于淬火钢,且其耐磨性随碳化钨质量分数的增加而提高:淬火钢的耐磨性随着载荷的增加迅速降低,而复合涂层的耐磨性则变化不大。