18Cr2Ni4WA钢的热敏感性与热处理工艺

Overheating susceptivity and heat treatment process of 18Cr2Ni4WA steel

通过加热炉模拟试验、组织观察、性能测试以及断口分析,研究了淬火温度对18Cr2Ni4WA钢组织性能的影响。结果表明：试验钢过热敏感性温度为990℃,1050℃左右晶粒会急速粗化。当淬火温度在820℃下,淬火温度稍高于奥氏体化温度点,试验钢中合金元素和碳化物未能均匀化,导致冲击性能较低。淬火温度由1010℃升高到1220℃时,冲击吸收能量由133 J降低到108 J,断面收缩率由64.5%降低到45.3%,奥氏体晶粒度的降低,导致冲击吸收能量开始大幅降低。为了提高淬火温度,降低保温时间,同时又不会明显降低奥氏体晶粒度和力学性能,应控制热处理淬火温度最高为970℃。

Effect of quenching temperature on microstructure and properties of 18 Cr2 Ni4 WA steel was investigated by means of heating furnace simulation test,metallography,mechanical property test and fractographic analysis. The results show that the overheating susceptivity temperature of the tested steel is 990 ℃ and the grain coarsens fast at 1050 ℃. When the quenching temperature is at 820 ℃,the temperature is slightly higher than the austenitizing temperature point,and the alloying elements and carbides in the tested steel are not homogenized,which leads to the low impact property. The impact absorbed energy decreases from 133 J to 108 J and reduction of area decreases from 64. 5% to 45. 3% when the quenching temperature increases from 1010 ℃ to 1220 ℃. The impact absorbed energy is lowered fast because of the decrease of austenite grain grade. In order to raise the quenching temperature and reduce the holding time without significantly reducing the austenite grain grade and mechanical properties,it is necessary to control the quenching temperature to 970 ℃.