Influence of cooling rates and tempering on the mechanical properties of Mn-Mo-Ni low-alloy steels
The microstructure and mechanical properties of Mn-Mo-Ni low-alloy steels were investigated at different level of cooling rates and tempering conditions.The steel plates cooling at 40℃/s and 30℃/min,the rates corresponding to the surface and half thickness of heavy steel plate during water quenching,produced microstructure of auto-tempered martensite and bainite respectively.During tempering,the strength of steels quenched at the two different cooling rates lowered continuously along with increase in the tempering parameter,defined by T( 20 + log t) where T:temperature and t:holding time.But the rate of strength change scales with the degree to which the virgin microstructure deviates from equilibrium.The strength of martensitic steel decreased faster and finally close to that of bainitic steel.The ductility and toughness gradually improved during tempering,passed through a maximum value,and finally lowered.The level of maximum toughness was also found to depend on cooling rates of Mn-Mo-Ni steels.The high cooling rate with microstructure of auto-tempered martensite showed larger toughness and lower ductile-brittle transition temperature than low cooling rate with microstructure of bainite,because the former had finer precipitated cementite particles at quenching and slower coarsing rate during tempering.
Mn-Mo-Ni low-alloy steel cooling rate tempering strength toughness
LIU Huibin ZHANG Hanqian
Baoshan Iron & Steel Co.,Ltd.,Shanghai 201900,China
国内会议
上海
英文
1-5
2013-06-01（万方平台首次上网日期，不代表论文的发表时间）