预备热处理对AMS 6308钢组织及性能的影响

 采用SEM、TEM和力学性能测试等手段，研究了预备热处理对AMS 6308钢组织及性能的影响。结果表明，980 ℃以下正火，随着温度的提高，M6C碳化物逐渐溶解，晶粒细小，淬火后马氏体板条均匀细小，碳化物呈球状或椭球状弥散分布在板条界和晶界上，碳化物体积分数和位错密度较高，强度和冲击值逐渐增加。980 ℃以上正火，M6C碳化物溶解增多，晶粒开始长大，淬火后马氏体板条束尺寸也长大，碳化物体积分数和位错密度下降，强度和冲击值降低。推荐的预备热处理制度：正火温度为980～1 010 ℃，回火温度为680～700 ℃，经性能热处理后，AMS 6308钢体现出良好的强韧性匹配。

Effect of preheat treatment on microstructure and mechanical properties of AMS 6308 steel

The effect of preheat treatment on microstructure and mechanical properties of AMS 6308 steel was investi-gated experimentally by means of SEM,TEM and mechanical properties tests. The results show that with elevating the normalizing temperature,M6C carbides dissolve gradually and grain size is small when normalized below 980℃,the martensite lath size is small,spherical and axiolitic M6C carbides precipitate along lath boundaries and grain boundar-ies,the content of M6C carbides and the dislocation density is very high after quenching,which leads to an increase of strength and toughness. While the steel sample is normalized above 980℃,the strength and toughness decrease duo to the increase of the martensite packet size and the decrease of the content of M6C carbides and the dislocation density. The recommended preheat treatment process includes:normalizing at 980-1 010℃,and tempering at 680-700℃,AMS 6308 steel shows a good combination of strength and toughness after property heat treatment.