余氏理论中原子平均共价电子密度研究

在价电子理论中提出了原子平均共价电子密度的概念 ,计算了马氏体中典型结构单元内各晶面上的原子平均共价电子密度 .研究表明 :在相邻晶面上的原子平均共价电子密度应连续是不同结构类型单元相邻的必要条件 ,把此条件应用于余氏理论的价电子结构计算中 ,可以消除或减少多重解 .     

渗碳硬化层性态的综合分析

通过对２０ＣｒＭｎＭｏ钢渗碳硬化层的组织结构，层内残余应力和硬度的分布以及渗碳硬化试棒的扭转性能进行系统的分析研究，经综合分析总结出２０ＣｒＭｎＭｏ钢的渗碳硬化层具有下列几个特点，即：（１）渗碳层中基本组织的主体是枣核马氏体，枣核马氏体基体由表及里一直可延伸到含碳量为０．５％的层深部位（即有效层深，ＨＶ５５０处）。（２）表面碳势为１．１％Ｃ的渗碳梗化层内，临近外表面部位的枣核马氏体中会出理显微裂纹     

提高M12螺帽冷镦模具耐磨性的研究

Cr12MoV钢制造的M12螺帽冷镦模经超低温改性处理后，其显微组织发生了转变：钢组织中的残留奥氏体向马氏体转变，析出大量高弥散的碳化物微粒，强化了模具性能，尤其是耐磨性能显著增加，从而提高了冷镦模具的使用寿命。     

热处理对耐热马氏体不锈钢0Cr17Ni4Cu4Nb性能的影响

0Cr17Ni4Cu4Nb钢是一种马氏体沉淀硬化不锈钢,多用作既要求不锈性及耐腐蚀性又要求高强度的轴类等部件,为保证性能要求,对此钢种进行试验研究,通过合理控制化学成分及调整热处理制度,摸索出热加工性能良好及在480℃时效处理后强度最高等各种工艺参数及不同热处理状态下的性能水平,满足了性能要求.     

低碳高强度钢的组织结构与回火马氏体脆化

低碳高强度钢25Si2Mn2CrNiMoV在450℃回火状态下产生回火马氏体脆性.本文重点研究了这种钢回火马氏体脆化与钢的组织结构间的关系,提出了碳化物——残余奥氏体——杂质元素交互作用引起回火马氏体脆化的简单模型.     

新型明弧硬面药芯焊丝研制

研制出了新型明弧硬面药芯焊丝 ,堆焊层的显微组织为马氏体加少量残余奥氏体 ,在马氏体上弥散分布着细小的碳化物、氮化物和碳氮化物质点 .试验结果表明 :新型明弧硬面药芯焊丝堆焊层的结合强度高 ,有良好的耐磨性能、抗疲劳裂纹和剥落性能 .堆焊层的硬度为 5 1～ 5 3HRC ,堆焊层硬度不均匀性为± 1.5HRC     

Microstructure of ultrahigh carbon martensite

Recent experimental investigations suggest that the martensite formed by quenching carbon steels(0.2–1.26 mass %C) are composed of twins and nanoscale ω particles in twin boundaries, rather than carbon supersaturated uniform solutions. In order to probe the microstructure of the martensite with ultrahigh carbon content, a novel strategy is employed in the present study to obtain ultrahigh carbon martensite(approximate2.1 mass %C) by quenching ductile cast iron. The microstructure of the martensite was intensively characterized by high resolution transmitting electron microscopy. It is indicated that the microstructure of the ultrahigh carbon martensites is composed of ultrafine {112} 111 -type twins and high-density nano-scaled ω particles embedded in twin boundaries. These ω nanoparticles in twin boundaries could remarkably impede the deformation of the movement of the nanotwins in martensites, leading to poor ductility and strength of the quenched ductile cast iron. These findings not only reveal the substructures of ultrahigh carbon martensite, but also enhance the understanding of the mechanical behavior of high carbon steels and ductile cast irons.     

Relationship among wear-resistance of three-body abrasion,substructure and property in martensite steels

The effects of subsurface hardness on wear-resistance of martensitic steel 20Cr, 40CrSi, 60Mn, T8 and T10 in three-body abrasion under static load was investigated. It shows that the characteristic ofthe subsurface hardness distribution and the abrasive wear resistanceis related to the substructure near the worn surface. The substructure of the tested martensite steel has an apparent relationship with thecarbon content and steels with moderate carbon content and hardness exhibit good resistance to abrasive wear. The competition of the work-hardening effect and the temper softening effect, which resulted from deformation and friction heat generating during abrasive wear is considered to be a main reason for the relation among wear-resistance, hardness and substructure. At the test conditions, the wear-resistance of 40CrSi is the best.     

NM400高强度低合金耐磨钢的组织与性能

采用Ti-Cr-B微合金化成分设计、奥氏体再结晶区直接轧制及淬火加低温回火的热处理工艺,开发出低成本的NM400级别高强度、高韧性的低合金耐磨钢板.利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)等对其组织、性能、断口形貌及析出物进行了研究.结果表明:试验钢的组织主要为高密度位错板条马氏体及分布在板条上的...