表面炭黑的成因及其对渗碳淬火钢件质量的影响

Origin of surface soot and its effect on quality of carburized and quenched steel workpieces

通过对比有炭黑和无炭黑20CrMnTiH钢渗碳淬火零件的表面色泽,分析了工件表面炭黑的形成原因,实测了有炭黑零件的表面硬度、淬硬层深度并观测了显微组织。结果表明:表面有炭黑的零件其淬硬层深度略深,表面硬度与无炭黑的零件相比大体一致,有炭黑零件在表面尖角附近处有较多非颗粒状碳化物,且形态迥异,其中条杆状碳化物长度达12μm。分析认为升温和强渗期过大的丙烷流量是形成炭黑的主要原因。

The generating reason of the surface soot was analyzed by comparison of carburized and quenched 20 CrMnTiH steel workpiece surface states with and without soot. Surface hardness,hardened depth and microstructure of the workpieces with soot were measured.Compared to that without soot,the results show that the hardened depth of the workpiece with soot is a little deeper,the surface hardness is more or less the same,and there are many non-granular carbides near the sharp corner of the soot-containing workpiece surface,and their morphologies are very different,among them the longest rod-like carbide is up to 12 μm in length. The analysis shows that temperature arising and strong carburizing periods too much propane during are the reason of the soot formation.