稀土微合金化5Cr21Mn9Ni4N钢晶粒长大规律

Grain Growth Behavior of 5Cr21Mn9Ni4N Steel Micro-Alloyed by Rare Earth

对5Cr21Mn9Ni4NRE气阀钢在不同固溶温度和不同保温时间下的奥氏体晶粒长大规律进行了系统研究。结果表明,5Cr21Mn9Ni4NRE钢在1150℃以上固溶处理时具有奥氏体晶粒急剧粗化的特征,稀土的加入有助于抑制晶粒长大,提高晶粒长大激活能,晶粒长大机制仍为自扩散过程控制机制。弥散分布的碳氮化物对晶粒长大有显著阻碍作用,在低于1100℃时,大量未溶解的碳氮化物使得晶粒尺寸增幅较小、洛氏硬度小幅下降;在高于1150℃时,随保温时间延长,晶粒急剧粗化,洛氏硬度下降较快。晶粒生长指数随固溶温度的升高而增加。

Grain growth behavior of 5Cr21Mn9Ni4NRE steel was experimentally studied at various solid solution treatment temperatures and holding for different times. The experimental results show that the 5Cr21Mn9Ni4NRE steel has the feature of sharp austenite grain coarsening after solid solution treatment at the temperature above 1150℃. RE added in the steel has the benefit to restrain grain growth and increase grain growth activation energy. Grain growth nism is self-diffusion controlling process. The mechadispersed carbo-nitride in the steel greatly restrains grain growth. Solid solution treatment at the temperature below 1100℃ leads to little increase of grain size and little decrease of Rockwell hardness for mass carbo-nitilde undissolved, whereas solid solution treatment at the temperature above 1150℃ leads to rapid grain coarsening and Rockwell hardness decreasing. Grain growth exponent increases with the increasing of solid solution treatment temperature.