FV520(B)钢时效组织和力学性能分析

通过透射电镜、电子拉伸、示波冲击试验,分析了马氏体沉淀硬化不锈钢FV520(B)850℃油淬后分别在560、600和630℃时效后的组织和力学性能。结果表明,淬火态FV520(B)钢560℃和600℃时效处理后,组织均为过时效马氏体+残余奥氏体,但细微组织有较大的差别,630℃时效处理后,组织为过时效马氏体+马氏体+ 残余奥氏体;560℃时效后强度最高;三种时效温度下,FV520(B)均具有较高的冲击韧度,600℃时效后冲击韧度最高;时效温度对FY520(B)冲击韧度的影响主要决定于其对塑性变形功(Apl)的影响。     

Microstructure of a nitrided steel previously decarburized

In this study the effects of a surface-controlled decarburization on the structure of a nitrided steel are analyzed. Samples of a quenched and tempered 42CrMo4 steel were decarburized by heating in air at different depths and submitted to gaseous nitriding. After decarburization and nitriding, the microstructure of surface layers was investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The nitrogen and carbon profiles in the diffusion layers were determined by SEM equipped with a wavelength dispersive spectrometer (EPMA-WDS) and by glow discharge optical spectrometry (GDOS). The effect of nitriding was determined by microhardness measurements. Our results indicate that a previous decarburization only slightly affects the surface hardness, but reduces the conventional nitriding depth. The decarburization also favors the nitrogen take-up and produces increased nitrogen concentrations in the compound layer and in the narrow zone beneath it.     

高速钢中贝氏体的二次硬化特征

研究了6-5-4-2高速钢中贝氏体和马氏体回火后的力学性能和组织结构。结果表明,贝氏体比马氏体具有更高的二次硬化效应以及抗回火稳定性和冲击韧性。透射电镜观察发现,马氏体在二次硬化峰温度范围回火时,有Fe_3C析出,而贝氏体铁素体和奥氏体中只析出弥散的MC和M_2C合金碳化物。这表明在贝氏体长大过程中存在合金元素的扩散。     

用快速冷却工艺生产高强度多相钢的实验研究

通过对含Nb微合金钢控制轧制后，进行快速冷却＋超快速冷却工艺的研究，得到了针状铁素体、板条马氏体及下贝氏体多相组织。实验钢在850℃终轧后，以高于50℃／s的冷却速度快速冷却到中间温度（600～550℃），空冷2～3s，之后采用超快速冷却至低温卷取。实验钢具有多相组织，屈服强度达到500MPa，抗拉强度明显提高，同时保证了强度和塑性的良好匹配，节约了生产时间。快冷与超快冷相结合的工艺为开发高强度微合金钢提供了新的实验手段。     

Steam oxidation resistance of two-layered Ni-Cr and Al APS coating for USC boiler applications

Thermal spray of Ni-Cr and Al coatings was attempted on modified 9Cr-1Mo steel, to evaluate their steam oxidation resistance. Atmospheric plasma spray (APS) coatings of 50Ni-50Cr as undercoat and Al topcoat were attempted with the aim that the pores produced by 50Ni-50Cr undercoat can be filled with Al topcoat during the steam oxidation. The steam oxidized samples evinced the Ni and Cr diffusion towards the Al coating structure and changed the topcoat in to the Ni-Al intermetallics. Though the two-layered coating exhibited an excellent performance against the steam oxidation for the base steel substrate till 3000 h of test, the top layers of the coating underwent significant internal oxidation.     

回火对国产P91钢组织和性能的影响

采用单因素比较试验法进行P91钢回火工艺参数的优化，研究回火温度和回火时间对力学性能和组织结构的影响，结果表明：P91钢正火后，再经760℃、180min的回火处理，获得了良好的力学性能和细小均匀的回火板条马氏体组织；回火温度过高会出现组织性能的异常变化。     

Fabrication and Characterisation of Rutile-TiO_2 Coatings on Metallic Alloy Substrates

RUTILE-TJO2is a versatile material possessing manyinteresting physical,chemical,optical and dielectricproperties[l].It is also a good tribological material thatcan offer low friction and low wear rate[2,3].However,the application of rutile in the tribological field hasbeen limited to titanium alloys only so far,for example,by thermal oxidation of titanium alloys[4,5].Very fewinvestigations have been directed to the tribologicalapplications of rutile films on substrates other thantitanium al…     

锚链钢弯环内侧开裂分析原因

对锚链钢弯环的原材料和车削后热处理材料及开裂的弯环进行低倍、组织、断口检验，结果表明弯环开裂是由车削后的热处理工艺和焊接工艺控制不当造成的。     

Complex magnetic and microstructural investigation of duplex stainless steel

Heat treatment induced microstructural processes were studied by different non-destructive magnetic methods in the present work. A commercial SAF 2507 type superduplex stainless steel was investigated. This alloy contains about 40% ferrite and 60% austenite phases in its initial condition. The ferrite phase is not stable, therefore it can decompose to sigma phase and secondary austenite due to heat treatment. All the mechanical, corrosion resistance and magnetic properties are strongly influenced by the microstructural changes. This study had two aims: to understand better the kinetics of the ferrite decomposition process and to study the application possibilities of the applied magnetic measurements. The results, which were supported by electronmicroscopic method (electron back scattered diffraction, EBSD), help us to understand better the microstructural changes in duplex stainless steels caused by heat treatment.     

离心铸造高速钢轧辊铸造缺陷形成与控制技术研究

采用离心铸造方法制造高速钢轧辊工艺简单,操作方便,但易出现偏析、裂纹、气孔、缩孔及夹杂等缺陷,影响轧辊的力学性能和使用性能.采用稀土-钛复合变质处理改善合金的组织和性能,同时改进离心铸造工艺参数可以消除高速钢轧辊铸造缺陷,提高力学性能,改善使用效果.