34CrNi3MoV钢奥氏体晶粒长大模型验证与应用

Verification and Application of Austenite Grain Growth Model in 34CrNi3MoV Steel

通过热处理试验并采用金相法分析研究了加热温度和保温时间对34CrNi3MoV钢奥氏体晶粒长大行为的影响。结果表明,加热温度对34CrNi3MoV钢奥氏体晶粒尺寸的影响尤为显著,随加热温度(900~1200℃)的升高,晶粒尺寸逐步增大。在初始晶粒尺寸情况下,900℃保温30 min(12.1μm)和950℃保温10 min(15.1μm)都与原始晶粒尺寸级别相差不大,1050℃保温30 min(37.8μm)时,晶粒尺寸达到原始晶粒尺寸的3.35倍,得到34CrNi3MoV钢晶粒长大的激活能Q=176.6 kJ/mol。随保温时间的延长,加热温度对奥氏体晶粒尺寸的影响越来越弱。950℃保温时,晶粒长大的临界保温时间大约为90 min左右。1050℃保温时,其临界保温时间大约为30 min。加热温度越高,达到临界保温时间后,晶粒长大就越缓慢。加热温度为850~950℃,保温时间60~180 min,可使34CrNi3MoV钢平均晶粒尺寸控制在22.5~44.9μm(国标8.0~6.0级)而满足要求。

The effects of heating temperature and holding time on austenitic grain growth behavior of 34CrNi3MoV steel were studied by heat treatment test and metallography.The results show that the effect of heating temperature on austenitic grain size of 34CrNi3MoV steel is particularly significant,and the grain size increases gradually with the increase of heating temperature(900-1200℃).In the case of initial grain size,both 900℃holding for 30 min(12.1μm)and 950℃holding for 10 min(15.1μm)have little difference with the original grain size level,and 1050℃holding for 30 min(37.8μm),The activation energy Q of grain growth of 34CrNi3MoV steel is 176.6 kJ/mol when the grain size is 3.35 times of the original grain size.With the extension of holding time,the influence of heating temperature on austenite grain size becomes weaker and weaker.At 950℃,the critical holding time for grain growth is about 90 min.At 1050℃,the critical holding time is about 30 min.The higher the heating temperature,the slower the grain growth after reaching the critical holding time.The heating temperature is 850-950℃and the holding time is 60-180 min,which can make the average grain size of 34CrNi3MoV steel controlled in 22.5-44.9μm(national standard 8.0-6.0)and meet the requirements.