S195球铁凸轮轴裂纹的研究

Study on the Cracks of S195 Cam-shaft Made of Ductile Iron

研究了球铁凸轮轴中频淬火后形成裂纹的原因,观察了宏观裂纹与微观裂纹的形貌,并测定了经不同工艺处理后凸轮的金相组织和残留奥氏体量。发现裂纹是由于热处理不当,产生粗大片状高碳马氏体及大量残留奥氏体,以及回火不充分和不及时等原因造成的。经改进后,使裂纹废品率由12%降至1.5%以下,取得了显著经济效益。

In this paper, the cause for forming cracks in the cam-shaft made of ductile iron after medium frequency induction hardening was investigated. The morphologies of macroscopic and microscopic cracks were observed by SEM, the microstructure and the amount of retained austenite in the cam undergone various heat treatment were tested. The results show that the formation of cracks is due to the coarse plate martensite containing high carbon along with a large amount of retained austenite caused by unsuitable heat treatment as well as unsufficient tempering etc. After the process is improved , the scrap rate is reduced from 12% down to below 1.5% and the remarkable econ(?)mic benefit is obtained.