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 mod...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 CO_2 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 CO_2 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.展开更多
It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and se...It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and semi-solid forming has been done in China. In order to produce the high quality die-casting, a novel innovation that modifies the present machines based on the SSP technique was proposed. Semi-solid die-casting on modified casting machines can manufacture parts with more excellent quality than those produced by squeeze casting. It was found that the defects such as 'elephant foot' and 'periphery liquid metal loss' during reheating could be avoided through controlling the non-dendritic structure of billets and optimizing the reheating process. The processing parameters and mold designs of semi-solid die-casting are fairly different from those of liquid die-casting.展开更多
文摘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 CO_2 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 CO_2 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.
基金This Work financially supported by the China National Advanced Materials Committee
文摘It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and semi-solid forming has been done in China. In order to produce the high quality die-casting, a novel innovation that modifies the present machines based on the SSP technique was proposed. Semi-solid die-casting on modified casting machines can manufacture parts with more excellent quality than those produced by squeeze casting. It was found that the defects such as 'elephant foot' and 'periphery liquid metal loss' during reheating could be avoided through controlling the non-dendritic structure of billets and optimizing the reheating process. The processing parameters and mold designs of semi-solid die-casting are fairly different from those of liquid die-casting.
