17CrNiMo6钢渗碳前的预备热处理

Prior Heat Treatments of 17CrNiMo6 Steel Before Carburizing

低碳钢零件渗碳前的预备热处理,包括正火、正火加高温回火、正火加调质处理等,对渗碳、淬火后零件的畸变和力学性能有一定的影响。因此,要进行渗碳的零件通常都进行预备热处理。为了确定最合适的预备热处理工艺,对17CrNiMo6钢进行了940℃正火、850油淬,随后650℃回火和940℃正火,再进行650℃回火的热处理,检测了钢的显微组织和力学性能。结果表明,17CrNiMo6钢正火加调质处理后的力学性能,特别是强度,明显比经正火加高温回火后的优越,前者的显微组织也比后者的均匀、细小。

Prior heat treatments for low-carbon steel part before carburizing, such as normalizing, normalizing then high tempering, and normalizing and quenching followed by high tempering, will exert a certain influence on distortion and mechanical properties of the part after carburizing and hardening. Consequently, parts that will be carburized largely are previously heat treated. In order to identify the best appropriate prior heat treatment procedure, 17CrNiMo6 steel was normalized by heating at 940 ℃ and air-cooling, quenched from 850℃ in oil then tempered at 650 ℃, and normalized by heating at 940 ℃ and air-cooling then tempered at 650 ℃. After this, the steel was subjected to microstructure survey and to mechanical property measurements. The results indicated that the 17CrNiMo6 steel exhibited much better mechanical properties, particularly strength property, and more uniform and finer microstructure after normalizing and quenching followed by high tempering than after normalizing and high tempering.