高频淬火加热时间对钢管表面组织和性能的影响

目的确定高频淬火后零件出现软点的原因,通过调整工艺参数以获得合格组织。方法通过直读光谱测试工件化学成分,采用体视显微镜、金相显微镜和扫描电镜观察试样的宏观与微观组织,分析工件的淬火层深度和显微组织形态。通过能谱仪测试样品淬火组织的成分差异。梳理生产过程,确定淬火零件软点形成的原因。结果通过扫描电镜配置的能谱仪测试发现,产生软点的样品黑色区域马氏体的碳含量较高,白色区域马氏体碳含量较低;未产生软点的样品黑区和白区马氏体的碳含量差别不大。结论高频淬火零件事先未经调质处理,碳含量分布不匀,高频淬火时间短,碳原子没有得到充分扩散,淬火后的零件在组织中形成了高碳和低碳马氏体两种结构,导致淬火后零件出现软点。

Effect of High Frequency Quenching Heating Time on Surface Micro-structure and Properties of Steel Tube

The work aims to determine causes of soft spot on parts after high frequency quenching and obtain qualified structure by adjusting process parameters. By reading chemical composition of spectrometry test workpiece directly, macrostructure and microstructure of samples were observed by stereo microscope, optical microscope and scanning electron microscope to analyze quenching layer depth and microstructure structure of workpiece. The composition difference in quenching structure of the samples was tested by energy spectrometer. The production process was sorted out to judge the possible causes of soft spot on quenching parts. Tested by the energy spectrometer configured by SEM, content of martensite in the black area of unqualified samples was high while that in the white area was low; for qualified samples, there was little difference in carbon content of martensite in black and white area. High carbon and low carbon martensite form in microstructure of the quenched parts and soft spot was present since high frequency quenched parts are not subject to prior thermal refining, carbon content distribution is not uniform, high frequency quenching time is short and carbon atoms are not fully diffused.