18CrNiMo7-6钢渗碳—渗硼层的组织和硬度  

Microstructure and Hardness of Case of 18CrNiMo7-6 Steel Subjected to Carburizing-Boronizing Treatment

作　　者：满金亮 宋锦柱[1] 樊新民[1] 

机构地区：[1]南京理工大学材料科学与工程学院,江苏南京210094

出　　处：《热处理》2016年第2期1-5,共5页Heat Treatment

摘　　要：对18CrNiMo7-6钢试样分别进行了这样的处理:940℃渗硼5 h,油淬和低温回火;先渗碳至0.5 mm,然后940℃渗硼5 h,油淬和低温回火。采用光学显微镜、扫描电镜、X射线衍射仪和显微硬度计检测了试样渗层的显微组织和硬度,以揭示预渗碳对18CrNiMo7-6钢渗硼的影响。结果表明,单一渗硼的18CrNiMo7-6钢试样渗层厚度为135μm,表面硬度为1 680 HV0.2;而经渗碳-渗硼的18CrNiMo7-6钢试样渗层厚度为150μm,表面硬度为1 710 HV0.2。两种试样的渗层均主要由Fe_2B相和少量FeB相组成。此外,渗碳-渗硼试样的过渡区宽度达1 600μm,远大于单一渗硼试样的过渡区宽度,从而显著改善了硼化物层的承载性能。18CrNiMoT-6 steel specimens were boronized at 940 ℃ for 5 h, oil-quenched and low tempered, and firstly carburized to 0.5 ram, then boronized at 940 ℃ for 5 h, oil-quenched and low tempered, respectively. The case of specimens was subjected to microstructural survey and hardness measurements by means of OM, SEM, XRD and micro-hardness tester to reveal effect of the pre-carburizing on the boronizing of the 18CrNiMo7-6 steel. The results show that the case is 135 μm thick, and the surface hardness is 1 680 HVO. 2 for the 18CrNiMoT-6 steel specimen only boronized, while the case is as thick as 150 μm, the surface hardness is as high as 1 710 HVO. 2 for the 18CrNiMoT-6 steel specimen firstly carburized and then boronized. The two kinds of case consist mainly of Fe2 B phase and a small amount of FeB phase. Furthermore, the transition zone of the specimen firstly carburized and then boronized is 1 600 μm wide which is significantly larger than that of the specimen only boronized, thus rendering the load-bearing ability of boride layer much better.

关 键 词：18CrNiMo7-6钢 渗碳 渗硼 渗碳-渗硼 显微硬度 

分 类 号：TG156.8[金属学及工艺—热处理]