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本文研究了18Cr2Ni4WA钢真空渗碳后热处理制度和渗层中残余奥氏体对力学性能的影响。结果指出,真空渗碳件表面无异常层,无脱碳现象。渗碳后重新加热淬火可使疲劳极限达90～95Kg/mm~2,比渗碳后直接淬火的(74Kg/mm~2)提高30％左右,比未渗碳的提高75～80％。前种处理制度可使渗层组织显著细化。两种制度的组织均为主要是孪晶型马氏体。扫描电镜观察断口指出前者主要是穿晶断裂,而后者主要是沿晶断裂。俄歇能谱仪分析指出,不存在P元素沿晶界富集,因此,沿晶断裂与P元素无关。渗碳样品的疲劳强度、抗拉强度、弯曲强度和冲击韧性均与渗层中残余奥氏体有关。随着渗层中残余奥氏体量(10～25％范围内)增多,这些性能指标均有提高。
In this paper, 18Cr2Ni4WA steel after vacuum carburizing heat treatment system and the residual austenite layer on the mechanical properties. The results show that the surface of vacuum carburizing parts without abnormal layer, no decarburization phenomenon. After carburizing and reheating, the fatigue limit can reach 90 ~ 95Kg / mm ~ 2, which is about 30% higher than that of direct quenching after carburizing (74Kg / mm ~ 2) and 75 ~ 80% higher than that of non-carburizing. The former treatment system makes the nitrided layer significantly refined. The organization of both systems is mainly twin-type martensite. Scanning electron microscopy fracture point that the former is mainly transgranular fracture, while the latter is mainly along the intergranular fracture. Auger spectroscopy analysis pointed out that there is no P element along the grain boundary enrichment, therefore, intergranular fracture and P element has nothing to do. Carburizing samples fatigue strength, tensile strength, flexural strength and impact toughness are related to residual austenite in the layer. With the increase of the amount of retained austenite in the infiltration layer (in the range of 10% to 25%), these performance indexes have been improved.