Recent process in special steel,heat treatment and surface modification of automotive components

摘要

Demand of improving the mechanical properties and productivity of automotive components while minimizing environmental impact makes the development of special steel combined with advance heat treatment and surface modification technologies become an important research area. Recently,to reduce CO2 emissions by saving the manufacturing time,the following new special steel and advance heat treatment methods were developed: （1 ） An anti-coarsening extra-fine case hardening steel for automobile gear was developed,whose carburizing temperature can be improved for conventional 930 - 950℃to 1 050℃without coarsening,and the carburizing time can be reduced by maximum 75%. （2） Various microalloyed steels for fracture splitting connecting rod were developed.By using the above-mentioned steel combined with Thermo Mechanical Control Process（TMCP） method,the manufacturing time can be reduced by 30%-40%. （3） Vacuum carburizing and mild carburizing combined with induction quenching are being developed to replace the traditional gas carburizing,and the CO2 emissions can be reduced by 20%-40%. （4） Intensive quenching is another new quenching technology which can be defined as cooling usually with pure water quenchant or low concentration water/salt solutions at a rate several times higher than the rate of ' normal' or conventional quenching,and the conventional effective case hardening depth can be reduce greatly and carburizing time can reduced. In addition,the high pressure gas quenching for reducing the quenching distortion and dual shot-peening for improving fatigue strength of gear will also be discussed. In a word,the present paper will focus on how to use the interaction among the development of special steel, advance heat treatment and surface modification to improve the strength of automotive components while reducing the manufacturing cost and impact to environment.