Effect of bulk heat treatment and plasma surface hardening on the microstructure and erosion wear resistance of complex-alloyed cast irons with spheroidal vanadium carbides

The results of an investigation of the effect of bulk quenching from temperature in the range of 760–1050°C, cryogenic treatment (–196°C) and surface plasma hardening on the abrasive-erosion wear of frugally alloyed V–Cr–Mn–Ni cast irons with spheroidal vanadium carbides have been presented in this article. It has been found that cast irons containing 5.0–7.5% V, 4.5–9.0% Cr, and 5.5–5.7% (total) of Mn and Ni after heat treatment have a 2–3-fold advantage in wear resistance compared to the prototype high-vanadium cast iron (11.9% V, 12.9% Mn). The maximum wear resistance of cast irons studied is achieved by quenching at 760°C followed by plasma surface hardening, as well as quenching at 840°C, followed by cryogenic treatment. These treatments result in the formation of an optimum microstructure that consists of spheroidal vanadium carbides, eutectic carbides M₇C₃, and a martensite-austenite matrix reinforced by secondary carbides. The increase in quenching temperature leads to an increase in the amount of residual austenite and decrease in the erosive wear resistance of cast irons.     

优化合金元素加入量对蠕墨铸铁耐磨性的影响

通过设计合金元素锑、硼、磷加入量的三因素、二水平的正交试验,研究了合金元素及其加入量对蠕墨铸铁的蠕化率、基体组织、硬度和耐磨性的影响。优选出了合金元素的加入量为：0．03％Sb,0．03％B,0．25％P,并对新材料进行了模拟磨损试验。结果表明：新研制的低合金蠕墨铸铁比铬钼铜硼磷灰铸铁的综合相对耐磨性提高17．56％,而生产成本有所降低。     

Surface topography and tribology of cast iron in boundary lubrication

This work aims to study and understand the influence of the surface topography on wear of grey cast iron used for heavy duty diesel engine cylinder liners. A micro-alloyed grey cast iron was tested with different surface topographies. These were polished surfaces, honed surfaces (with two different honing parameters) and three model surfaces with well defined grooves on a polished specimen.Reciprocating friction tests using a steel ball rubbing against a flat or a cylindrical sample (extracted from a cylinder liner) were carried out on a Cameron Plint test rig. A commercial synthetic oil for diesel engine was used as the lubricant. The friction coefficient and the electrical contact resistance were measured during the tests. The wear volume of the cylinder liner part was also measured at the end of the test.The influence of the surface topography on the tribochemical film formation and on the wear behaviour of cast iron was established. Surfaces exhibiting lots of surface asperities had the highest wear, mainly due to delayed formation of protective tribochemical film. In our test conditions, the spacing between the grooves on model specimens had no influence on the wear behaviour of the cast iron specimens.     

锰硼奥氏体基高铬铸铁的组织结构及抗磨性研究

研究了四种不同含B量的Fe-Cr-Mn-C-B系铸造合金的铸态组织结构及摩擦磨损特性。结果表明：硼碳化物体积分数随B含量增加而增大，并可按等量原子比估算。由于含B合金基体表面更易摩擦诱发马氏体相变，且产生表面细晶强化作用，显著提高了滑动磨损的抗磨性。含硼0．3％时，滑动磨损的抗磨性是25Cr马氏体基合金的4倍，是Mnl3铸钢的7．6倍。     

中碳多元合金钢破碎机锤头的研制

对采用Cr、Mo、Ni及Mn等元素多元合金化中碳合金钢锤式破碎机锤头的组织、力学性能及耐冲击磨损性能进行了试验研究。锤头采用自硬树脂砂工艺铸造 ,对所研制的锤头进行了现场装机试验。试验结果表明 :合金元素含量分别为 :w(Cr) =4～ 5 %、w(Mo) =0 5～ 0 7%、w(Ni) =0 3～ 0 5 %、w(Mn) =0 6～ 0 9% ,含碳量为 :w(C) =0 4～ 0 5 %的中碳多元合金钢锤头具有高耐冲击磨损和良好韧性相结合的特点 ,其工作寿命为高锰钢锤头的 1 5 5倍     

热处理对Cr28Ni3和Cr15No3的影响

本文通过对Cr28Ni3和Cr15No3铸铁的显微组织、硬度及耐磨性的试验,结果表明950℃1050℃空冷处理后对Cr28Ni3铸铁影响较小,而使Cr15No3铸铁的硬度和耐磨性较大幅度提高。     

灰口铸铁激光表面合金化的凝固组织与性能

本文探讨了灰口铸铁激光表面合金化Si的快速凝固组织的形成过程与机理。合金化组织的成分为≤2.0%C及1.62%～9.21%Si,硬度值在830～1120HV范围内。在激光快速加热及随后的快速自传导冷却过程中,随合金熔体的凝固速率及陡降的温度梯度变化,凝固组织的形态及尺寸发生变化。借助于扫描电镜、能谱仪和透射电镜,对其组织及相分布进行了观察与分析,揭示了合金化组织的硬化机理。磨损试验结果表明,这种高硬度的凝固组织具有很好的耐磨性。     

RESEARCH AND APPLICATION OF AS-CAST WEAR RESISTANCE HIGH CHROMIUM CAST IRON

ＲＥＳＥＡＲＣＨＡＮＤＡＰＰＬＩＣＡＴＩＯＮＯＦＡＳＣＡＳＴＷＥＡＲＲＥＳＩＳＴＡＮＣＥＨＩＧＨＣＨＲＯＭＩＵＭＣＡＳＴＩＲＯＮＬｉｕＪｉｎｈａｉＬｉｕＧｅｎｓｈｅｎｇＬｉＧｕｏｌｕＨｅｂｅｉＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏｌｏｇｙＷａｎｇＫｕ...     

冷激合金铸铁气门挺杆表层组织对其耐磨性的影响

为了深入了解冷激合金铸铁气门挺杆的磨损规律,研究了冷激合金铸铁气门挺杆表层组织对耐磨性的影响.结果表明:当气门挺杆组织中的石墨以点状均匀分布,碳化物呈细小针状、块状,分布较为均匀时,耐磨性较好,磨损形式以划伤、点蚀为主;当气门挺杆组织中的石墨以片状均匀分布,碳化物呈粗大针状、块状,分布不均匀时,耐磨性较差,磨损形式以剥落为主.     

Cr/C对含4%Ni高铬耐磨耐蚀铸铁性能的影响

采用对比试验的方法探讨了不同Cr/C的比值对含4%Ni高铬耐磨耐蚀铸铁硬度、耐磨性及冲击韧性的影响规律。结果表明:无论固定C还是固定Cr,改变Cr/C的比值对4%Ni高铬耐磨耐蚀铸铁性能都有显著的影响,尤其当含C量较低时,Cr的变化对材料性能的影响更明显。通过调整不同的Cr/C,可以获得不同的硬度、耐磨性和冲击韧性组合的材料。     

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.     

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。     

Abrasive wear resistance of spheroidal vanadium carbide cast irons

The effect of the chemical composition and heat treatment on the microstructure and abrasive wear resistance of V-Mn, V-Ni-Cr, and V-Mo spheroidal vanadium carbide cast irons (18–23 vol %) has been studied. The wear resistance has been determined under conditions of wear by abrasives with various hardnesses, i.e., corundum and quartz and compared to that of high-chromium cast iron with 13% Cr. It has been found that the advisability of using high-vanadium cast irons is governed by the hardness of the abrasive. When a hard abrasive, i.e., corundum was used, V-Mo cast iron with the maximum concentration of spheroidal VC carbides, which were uniformly distributed in the martensitic matrix, had the highest wear resistance. When a soft abrasive, i.e., quartz, was applied, high-chromium cast iron with a hardness of 68 HRC, which contained the largest amount of M₇C₃ carbides, was more wear-resistant. In the course of isothermal exposure at 300–1000°C, V-Ni-Cr and V-Mo cast irons with an austenitic structure had high resistance to phase and structural transformations. However, the properties and microstructure of V-Mo cast irons with a martensitic matrix depended strongly on the temperature of exposure during heat treatment.     

Tribological characteristics of one-process and two-process cylinder liner honed surfaces under reciprocating sliding conditions

This paper reports an experimental study of the effect of surface texture on cylinder liner wear. This research is important because the conjunction between piston rings and cylinder liner is one of the major sources to frictional losses in internal combustion engines. Experiments were conducted on a reciprocating tester. Specimens were cut from cylinder liners honed or plateau honed made of grey cast iron of hardness 218 HB. The honing operation was performed in order to obtain very similar values of the Sq parameter of one-process and two-process surfaces. In addition, one-process specimens characterised by different Sq parameter values were tested. Counter-specimens were made from chromium-coated steel C45. It was found that wear of two-process surfaces was lower than that of one-process surfaces characterized by the same Sq parameter. Linear wear of specimens was proportional to initial Sq parameter value. The effect of additional oil pockets created by the burnishing technique on cylinder liner wear was negligible.     

高铬铸铁中残余奥氏体对冲击疲劳磨损的影响

采用MLD-10磨损试验机及附加装置研究高铬铸铁中残余奥氏体对冲击疲劳磨损的影响。试验得出,残余奥氏体可阻止疲劳裂纹的萌生和扩展,提高冲击疲劳抗力,降低冲击疲劳磨损。     

Performance and surface alloying characteristics of Cu–Cr and Cu–Mo powder metal tool electrodes in electrical discharge machining

The main objective of this study is to investigate the effect of Cu–Cr and Cu–Mo powder metal (PM) tool electrodes on electrical discharge machining (EDM) performance outputs. The EDM performance measures used in the study are material removal rate (MRR), tool electrode wear rate (EWR), average workpiece surface roughness (R_a), machined workpiece surface hardness, abrasive wear resistance, corrosion resistance, and workpiece alloyed layer depth and composition. The EDM performance of Cu–Cr and Cu–Mo PM electrodes produced at three different mixing ratios (15, 25, and 35 wt% Cr or Mo), compacting pressures (P_c = 600, 700, and 800 MPa), and sintering temperatures (T_s = 800, 850, and 900 °C) are compared with those machined with electrolytic Cu and Cu PM electrodes when machining SAE 1040 steel workpiece. Analyses revealed that tool materials were deposited as a layer over the work surface yielding high surface hardness, strong abrasion, and corrosion resistance. Moreover, the mixing ratio, P_c, and T_s affect the MRR, EWR, and R_a values.     

A study of sand slurry erosion of W-alloy white cast irons

This paper reports the results of a study into the effects of the composition, hardness and electrochemical properties of W-group cast irons on sand slurry-erosion resistance and wear mechanisms. The results indicate that the sand slurry-erosion resistance of the irons can be raised by increasing the content of tungsten, especially when the iron is alloyed with chromium. The relation between macrohardness and sand slurry-erosion is intricate. In the low hardness range, the sand slurry-erosion resistance is linearly increased with hardness, but this relationship does not exist in the high hardness range. The sand slurry-erosion resistance of cast iron can be considerably increased by increasing its corrosion resistance. Sand slurry-erosion is an abrasive wear process accompanied by corrosion and cavitation, all of which aggravate each other.     

发动机气缸腐蚀磨损及其交互作用研究

为了分析研究柴油机气缸套工作过程中的交互作用,选用灰铸铁材料在硫酸腐蚀介质中进行磨损试验、腐蚀试验及腐蚀磨损实验,分析了腐蚀磨损交互作用图。结果表明：腐蚀介质促进交互作用,磨损及其磨损增量是材料腐蚀磨损的主体。     

Corrosion-Wear Resistance and Interfacial Morphologies of Novel Fe–Cr–B Cast Steels in Molten Aluminum

In order to improve the corrosion–wear resistance properties of steels in molten aluminum, novel Fe–Cr–B cast steels with different boron concentrations were prepared. The steels were investigated at 750 °C for 0.5 h using a ring-block corrosion–wear test, and the interfacial morphologies were examined. Results showed that the corrosion–wear resistance of the Fe–Cr–B cast steel was three times that of H13, and benefited greatly from the effects of the primary Cr-rich Fe₂B, which bore the main load during the corrosion–wear test. The corrosion–wear behavior of the coarse primary Cr-rich Fe₂B in molten aluminum was clearly different from that in static molten aluminum.     

耐盐卤腐蚀铸铁的研究及应用

采用失重法及电化学法测试了低合金对耐盐卤腐蚀铸铁的影响。采用显微分析技术分析了合金元素的分布。在广泛深入研究的基础上，获得了具有良好抗含H2S盐卤腐蚀的低合金铸铁。