SAE8620H的淬透性对热处理变形的影响

利用C型缺口试样研究了不同淬透性的SAE8620H齿轮钢的渗碳热处理变形,并对C型缺口试样心部微观组织和硬度进行了分析.结果表明,SAE8620H齿轮钢在距淬火端9 mm处的硬度低于32HRC时,C型缺口试样心部主要为贝氏体组织,渗碳热处理变形较小;随着淬透性的提高,试样心部马氏体组织逐渐增加,渗碳热处理变形显著增大.不同淬透性的SAE8620H齿轮钢的相变组织不同,因而渗碳热处理变形不同.

Effect of hardenability of SAE8620H on its distortion by heat treatment

Effect of hardenability on distortion by heat treatment for SAE8620H gear steel was investigated by means of Navy-C ring specimens after carburization.Meanwhile,the microstructures and hardness in the centers of cross sections of C-ring specimens were analysed.The results show that when the hardness value at the distance of 9 mm from quenched end in Jominy test is below 32HRC,there is mainly bainite in the center of cross section of C-ring specimen,which has small distortion by heat treatment.The volume fraction of martensite in the center of cross section of C-ring specimen increases when the hardness value at the distance of 9 mm from quenched end increases from 32HRC to 35HRC.The distortion by heat treatment of SAE8620H steel increases slowly in the original stage and rapidly in the subsequent stage with increase of the hardness value at the distance of 9 mm from quenched end due to difference in phase transformation.