奥氏体中锰钢的耐磨性与形变诱发马氏体及位错强化的关系

本文利用电镜和X射线等检验手段及磨损与现场运行实验,研究了非强烈冲击工况下奥氏体中锰钢的耐磨性与形变诱发马氏体和位错强化的关系。实验结果表明：奥氏体稳定性低的中锰钢,由于形变诱发马氏体的产生及其与位错交互作用促进了加工硬化能力和耐磨性的提高,而奥氏体稳定性高的中锰钢则是由于溶质原子和第二相粒子与位错产生的交互作用所致。因此降低碳、锰含量,大量形成第二相弥散硬粒子或增加溶质原子深度是提高奥氏体中锰钢加工硬化能力和耐磨性的有效途径。     

热轧奥氏体中锰耐磨钢的磨料磨损性能研究

以热轧BTW中锰钢板为实验材料,借助ML-100磨料磨损试验机,研究以煤泥粉为软质磨料和石英砂为硬质磨料时其磨料磨损性能,利用SEM分析其磨损机制。实验结果表明,软质磨料磨损工况条件下,热轧奥氏体中锰钢和高锰钢的相对耐磨性低于马氏体耐磨钢,硬质磨料磨损工况条件下,热轧奥氏体中锰钢的相对耐磨性高于高锰钢和马氏体耐磨钢,因此热轧中锰钢更适用于硬质磨料磨损工况;无论软质和硬质磨料磨损工况,热轧中锰钢的加工硬化均高于热轧高锰钢,表现出更好的加工硬化性能。煤泥粉软质磨料对热轧中锰钢的磨损机制表现为微观切削磨损,伴随局部的疲劳剥落;石英砂硬质磨料对热轧中锰钢的磨损机制则为典型的凿削磨损和微观切削磨损。     

Fe-C-Cr-Mn亚稳奥氏体基铸造合金的摩擦磨损表层特性

研究了Fe-1.85C-8.03Cr-3.55Mn亚稳奥氏体基铸造合金的摩擦磨损表层特性，在较低的摩擦应力作用下，表层即可应变诱发α和ε马氏体。马氏体转变量随奥氏体形变量增加而增大，硬度也提高。由原奥氏体引起的表面硬度提高的原因：α和ε马氏体的形成；产生大量的位错和层错。在滑动磨损试验时，该合金的耐磨性高于25%Cr马氏体基白口铸铁。     

残余奥氏体对马氏体球铁耐磨性的影响

针对马氏体球铁，研究了不同残余奥氏体量对两体磨损试验和冲击磨料损试验的影响。结果表明，残余奥氏体对耐磨性的影响与磨损机制及加载方式有关：当静载荷时，残余奥氏体对疲劳机制控制的磨损耐磨性有利，而对切削机制控制的磨损耐磨性的影响不大，；当冲击载葆尤其当冲击载荷大时，残余奥氏体的存在对耐磨性不利。     

奥氏体中锰钢的冲滚磨料磨损性能研究

为寻找一种中低冲击载荷下具有良好耐磨性能的奥氏体中锰钢,以提高刮板输送机中部槽的耐磨性能和使用寿命,选择热轧奥氏体中锰钢Mn8,利用M2000摩擦磨损试验机研究其冲击滚动磨料磨损性能;结合SEM、XRD和TEM等测试手段,分析Mn8钢的磨损和强化机制。研究表明:在相对较低的冲滚载荷下,Mn8钢就能形成一定厚度的硬化层,且硬化层的厚度和耐磨性随载荷的增大而增大,同时体积磨损率变低。Mn8钢的磨损机制为凿削、犁沟等塑性变形以及交变应力导致的疲劳脆性剥落;Mn8钢的加工硬化机制是产生了高密度的位错缠结塞积(位错胞、层错)、形变诱导马氏体以及形变孪晶,从而使其在磨损过程中得到强化。     

Fe-C-Cr-Ni亚稳奥氏体基合金的摩擦磨损表层特性

对Fe－1．9C－16．5Cr－2．6Ni亚稳奥氏体基合金在不同试验条件下的摩擦磨损表层研究表明，在较低的摩擦应力作用下，表层即可应变诱发α’和ε马氏体。马氏体转变量随原奥氏体形变量增加而增大，硬度也增高。由原奥氏体引起的表面硬度提高的原因：（1）α’和ε马氏体的形成；（2）产生大量的位错和层错。在滑动磨损试验时，该合金的耐磨性高于25％Cr马氏体基白口铸铁。     

Fe—C—Cr—Ni亚称奥氏体基合金的摩擦磨损表层特性

对Ｆｅ－１，９Ｃ－１６．５Ｃｒ－２．６Ｎｉ亚稳奥氏体基合金在不同试验条件下的摩擦磨损表面研究表明，在较低的摩擦应力作用下，表层即可应变诱发α′和ε马体体。马氏体转变量随原奥氏体形变量增加而增大，硬度也增高。由原奥氏体引起的表面硬度提高的原因：（１）α′和ε马氏体的形成；（２）产生大量的位错和层错。在滑动磨损试验时，该合金的耐磨性高于２５％Ｃｒ-马氏体基白口铸铁。     

硬质颗粒复合合金的组织和耐磨性

本文强调基体合金组织对硬质颗粒复合合金耐磨性的决定作用,设计并通过“真空吸附铸件表面合金化工艺”,在灰铁铸件表层稳定地制得了以不同粒度的铸造碳化钨颗粒均匀分布于高合金铬钨白口铸铁中的复合合金。磨料磨损试验表明：基体合金组织对复合合金二体尤其是三体高应力磨损耐磨性有决定性的作用;以马氏体合金白口铁为基体合金的复合合金,在二体及三体磨损条件下均具有极高的耐磨性,铸造碳化钨颗粒愈粗,复合合金耐磨性愈高,当颗粒尺寸由140～200目增大到18～28目时,其在二体和三体磨损条件下的耐磨性分别是马氏体白口铁15Cr2Mo1Cu的9～31倍和2.8～6.7倍。     

奥氏体合金堆焊金属抗冲击磨损特性分析

针对高应力磨粒磨损工况条件研制的中铬C－Co－Mo系奥氏体合金堆焊材料FAW焊条，具有焊接工艺好，堆焊金属抗裂性好和加工硬化率高的特点，是替代奥氏体锰钢的理想焊接材料。通过对该材料的硬化和磨损性能及其机理的试验研究，探讨了合金的冷作硬化及冲击磨损的一般规律。     

不同磨损介质下铜锌铝形状记忆合金滚动磨损性能与磨损机制研究

研究了3种成分铜锌铝形状记忆合金在不同磨损介质下的滚动磨损性能，用扫描电镜对磨损表面进行了观察，分析了不同介质下合金失重机制。结果表明：油润滑条件下，不同相变温度的合金耐磨性有差异，马氏体相合金比β相合金耐磨，其失重机制主要为磨粒磨损；在酸、碱条件下，合金的相变温度对舍金的耐磨性几乎没有影响，原因在于酸、碱破坏了合金磨损表面的组织，使其不能发挥形状记忆合金所具有的应力诱发马氏体相变和马氏体的择优取向的特性，其磨损失重机制主要为粘着磨损和腐蚀磨损。     

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.     

Unlubricated sliding and rolling/sliding wear behavior of continuously cooled, low/medium carbon bainitic steels

The development of low and medium carbon bainitic steels for railroad track applications is traced through investigations to understand wear behavior. Carbide-free bainite consisting of bainitic ferrite laths, with or without lath boundary retained austenite, has emerged as the best microstructure. Cast and wrought 0.25%C, 1.75%Si, Mo-B steels have exhibited wear resistance comparable with that of Hadfield's austenitic steel under severe rolling/sliding contact.     

高锰钢和贝氏体钢辙叉失效机理及其磨面组织

以实际铁路线路上过早失效的高锰钢辙叉和贝氏体钢辙叉为研究对象,利用金相、扫描电镜、透射电镜和MÖssbauer谱等分析方法研究两种失效辙叉残体磨面组织结构的变化,并探讨其失效机理。结果分析表明,两种辙叉在服役过程中表面组织都发生纳米化反应,高锰钢辙叉在服役过程中表面奥氏体内产生少量碳原子聚集的现象,其失效形式是磨损、压溃变形和疲劳剥落;贝氏体钢辙叉失效的原因是磨损和氢致脆性剥落。从而提出增加辙叉使用寿命和提高铁路运行安全的方法和途径。     

Study of the surface layers of high-alloyed steels in braking

Specimens of high-alloyed steels for use in the brake-disk crowns of high-speed railway cars are subjected to tribotests. The surface-layer structure of a disk from steel 20Kh13 is studied. The wear-resistance features and temperature distribution in high-alloyed steels are described during braking. It is shown that within the range of moderate sliding velocities, alloyed high-chrome steels containing manganese and nickel are more wear-resistant and possess a lower friction coefficient, while in the range of fast sliding velocities steels free of alloying elements possess the maximum wear resistance.     

Tribological Behavior of New Martensitic Stainless Steels Using Scratch and Dry Wear Test

This paper focuses on the tribological characterization of new martensitic stainless steels by two different tribological methods (scratch and dry wear tests) and their comparison to the austenitic standard stainless steel AISI 316L. The scratch test allows obtaining critical loads, scratch friction coefficients, scratch hardness and specific scratch wear rate, and the dry wear test to quantify wear volumes. The damage has been studied by ex situ scanning electron microscopy. Wear resistance was related to the hardness and the microstructure of the studied materials, where martensitic stainless steels exhibit higher scratch wear resistance than the austenitic one, but higher hardness of the martensitic alloys did not give better scratch resistance when comparing with themselves. It has been proved it is possible to evaluate the scratch wear resistance of bulk stainless steels using scratch test. The austenitic material presented lower wear volume than the martensitic ones after the dry wear test due to phase transformation and the hardening during sliding.     

磷对高锰钢热塑性的影响

奥氏体高锰钢的锻造工艺性能十分差,它一直是工程中难以解决的技术问题.利用Gleeble-3500热模拟试验机测试不同杂质含量高锰钢的热塑性,研究磷对高锰钢热塑性的影响规律.利用KYKY-2800型扫描电子显微镜分析高锰钢试样合金元素和杂质元素的成分分布.同时,研究了锻造高锰钢的常规力学性能,并与铸造高锰钢进行对比.结果分析表明,磷显著降低高锰钢的零塑性温度、缩小高锰钢的塑性温度区间,并且,高锰钢零塑性温度与磷含量之间的关系为:T=1 220-1 520·wp%.因此,磷是导致高锰钢锻造工艺性能差的主要原因.其原因是它在奥氏体晶界偏析形成Fe-(Fe Mn)3P类低熔点共晶组织.锻造高锰钢的力学性能明显优于铸造高锰钢,因此,锻造处理将使高锰钢的应用领域进一步扩大.     

提高高锰奥氏体超低温钢低温韧性的方法

研究改进热处理工艺和加入合金元素来消除锰在奥氏体晶界上的不平衡偏聚以提高钢的低温韧性。降低固溶处理温度和冷却速度,以及在钢中加入铬、硼和钼,消除了锰的不平衡偏聚从而提高了高锰奥氏体超低温钢的低温韧性     

Effects of different metals on adhesive wear behaviour of alloy surface produced by TIG process

Abstract

Low carbon steel surfaces were alloyed with composite powders using the tungsten inert gas welding method. After the alloying process, the effects of cladding surface on the microstructural characteristics and adhesive wear of the alloyed samples were examined. The sliding wear behavior of samples was investigated in a block on ring apparatus under the loads of 20, 40, 60 and 80 N respectively. In the experimental investigation, a low carbon steel surface was alloyed with austenitic stainless steel powder and austenitic stainless steel powder mixed with 4·5% Co, Mo and Ti particles respectively. Following surface alloying, conventional characterisation techniques, such as optical microscopy, scanning electron microscopy, energy dispersive spectrograph and X-ray diffraction, were used to study the microstructure of the alloyed zone. Examination of the microstructure revealed the presence of M₂₃C₆ carbides, solid melt phases and intermetallic phases, such as Ni₃Ti, depending on the alloying element in the composite. As the amount of the reinforcing material increased, the saturation rates for the samples decreased, while their hardness increased. The adhesive abrasion tests conducted revealed that temperature input plays a significant role on the microstructure characteristics, which positively affected the adhesive abrasion values of the samples. Consequently, the tungsten inert gas welding method was successfully used for the surface alloying of low carbon steels.