采用OM、SEM、EBSD和Vickers硬度计等手段,并结合低温冲击试验,研究了不同淬火温度对40CrNiMo钢回火组织及其力学性能的影响.结果表明:当淬火温度为700和740 ℃时,40CrNiMo钢的回火组织均为铁素体和回火索氏体,回火硬度基本相近,分别为196.2和194.0 HV;当淬火温度升高至850 ℃,回火组织为回火索氏体,实验钢的硬度达到最大值235.7 HV,冲击功为26.3 J,综合力学性能较好.当回火温度为630 ℃时,不同淬火温度对40CrNiMo钢的冲击性能影响较小,-20 ℃的冲击功基本保持在26~30 J.
Effect of heat treatment process on microstructure and mechanical properties of 40CrNiMo steel
The influence of quenching temperature on tempering structure and mechanical properties of 40CrNiMo steel was studied by OM,SEM,EBSD and Vickers hardness tester and low temperature impact test.The results show that the tempering microstructure of 40CrNiMo steel is both ferrite and tempered sorbite at the quenching tem-perature of 700 and 740 ℃,and the tempering hardness is almost the same of 196.2 and 194.0 HV,respectively.As the quenching temperature increases to 850 ℃,the tempered microstructure is tempered sorbite.The hardness of the tested steel reached its maximum of 235.7 HV with an impact energy of 26.3 J,and it shows the better gen-eral mechanical properties.When the tempering temperature is 630 ℃,different quenching temperatures have little effect on the impact performance of 40CrNiMo steel,and the impact energy at-20 ℃ is basically maintained at 26-30 J.