卷取温度对模拟热轧51CrV4钢显微组织和力学性能的影响

Influence of coiling temperature on microstructure and mechanical properties of 51CrV4 steel under simulatied hot rolling

利用OM、SEM、EBSD及TEM等技术研究了卷取温度对51CrV4钢组织和硬度的影响,探讨并分析了不同卷取温度下组织和硬度变化的原因。结果表明,随着卷取温度由600℃升高至720℃,试验钢的硬度先逐渐降低,690℃以上变化不大;先共析铁素体的体积分数由0.33%增大至5.9%,铁素体晶粒尺寸逐渐增大;珠光体平均片层间距由93 nm增大到177 nm。卷取温度由630℃升高至720℃,(V,Cr)C析出相的平均尺寸由8.3 nm增大至9.7 nm,体积分数由0.247%递减至0.176%。珠光体片层间距是影响试验钢不同卷取温度强度/硬度变化的最主要因素,铁素体晶粒尺寸和纳米(V,Cr)C析出相的影响次之。

Effect of coiling temperature on microstructure and hardness of 51CrV4 steel was investigated by means of OM,SEM,EBSD and TEM. The variation of microstructure and hardness under different coiling temperature was discussed. The results show that with increasing coiling temperature from 600 ℃ to 720 ℃,the hardness of the steel decreases gradually first,then changes little over 690 ℃; the volume percentage of pro-eutectoid ferrite increases from 0. 33% to 5. 9%,and the grain size of ferrite increases gradually; the average lamellar spacing of pearlite varies from 93 nm to 177 nm. As the coiling temperature increases from 630 ℃ to 720 ℃,the size of（ V,Cr） C precipitates varies from 8. 3 nm to 9. 7 nm,oppositely,the volume fraction of（ V,Cr） C decreases from 0. 247% to 0. 176%. The average lamellar spacing of pearlite is the main factor for the change of strength and hardness of the 51CrV4 steel,the influence of the grain size of ferrite and（ V,Cr） C precipitates followed.