变形和回火时间对F40微合金钢组织与性能的影响

Effects of deformation and tempering time on microstructure and properties of F40 micro-alloyed steel

利用电阻加热结合天锻锻压机对F40微合金钢试样进行不同程度的变形,之后在700℃进行不同的时间回火处理;通过OM、SEM和TEM研究其组织变化,采用电阻仪和显微硬度计测量其电阻率和显微硬度。结果表明：变形量越大,其板条状组织越紊乱,且随着回火时间的延长,板条状组织逐渐呈多边化,回火120 min时局部有小角度亚晶以及位错胞形成;电阻率和硬度随回火时间的变化规律均为先降后升再降,最后趋于稳定;而变形量越大,其电阻率和硬度值越高,达到峰值的时间也越快。

F40 microalloy steel samples were deformed in varying degrees by using resistance heating and forging press,then tempered at 700 ℃for different time. The microstructure was studied through the means of OM,SEM and TEM,and the electric resistance and hardness were measured by resistance meter and micro-hardness instruments. The results show that the larger the deformation is,the more disordered the lath structure becomes. And the lath structure gradually becomes polygonal when the tempering time increases. When the tempering time is120 min,there are some small angle subgrains and dislocation cells form locally. When the tempering time increases,the resistivity and hardness of samples first decrease,then increase and finally decrease to stable values. Moreover,the larger the deformation is,the higher the resistivity and hardness are,and the faster to reach their peak values.