38CrMoAl钢表面超细贝氏体组织的研究

研究了38CrMoAl钢表面获得超细贝氏体组织的热处理工艺及其组织结构特征。首先利用自行设计的滴注式可控气氛全自动渗碳炉，在930℃对该钢渗碳8h，使钢表面的碳的质量分数达到0．85％，渗层深度为2mm。将经过渗碳热处理的试样加热到930℃保温20min进行奥氏体化处理。然后直接淬入温度分别为230、255和280℃的...

Ultrafine Bainite in the Surface Layer of 38CrMoAl Steel

The heat treatment to obtain ultrafine bainite in the surface layer of 38CrMoAl steel and the microstructure characteristics of ultrafine bainite were investigated. The samples carbonized at 930℃ for 8h were heated at 930℃ for austenitization and then isothermal quenched at different temperatures in salt bath. The microstructures were investigated in the carburized layer by optical microscopy and transmission electron microscopy (TEM), and the hardness was tested by HV-sclerometer. The results show that the samples which were isothermal quenched at 230℃ for 10h and 255℃ for 4h have obtained ultrafine bainite in the surface layer. The plate of ultrafine bainitic ferrite was as thin as 80nm and film of retained austenite can reach a thickness of several nanometers; the mixstructures of the ultrafine bainite and low carbon martensite were formed in the transition layer, the low carbon martensite was formed in the center. The ultrafine bainite exhibits high rolling contact fatigue performance compared to the martensite under conventional quenching and tempering.