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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。
The effects of coiling temperature on the microstructure and hardness of 51CrV4 steel were investigated by OM, SEM, EBSD and TEM techniques. The reasons for the changes of microstructure and hardness at different coiling temperatures were discussed and analyzed. The results show that as the coiling temperature increases from 600 ℃ to 720 ℃, the hardness of the test steel decreases first and then changes little above 690 ℃. The volume fraction of proeutectoid ferrite increases from 0.33% to 5.9% The grain size of ferrite increases gradually; the average lamellar spacing of pearlite increases from 93 nm to 177 nm. When the coiling temperature increased from 630 ℃ to 720 ℃, the average size of (V, Cr) C precipitates increased from 8.3 nm to 9.7 nm, and the volume fraction decreased from 0.247% to 0.176%. The pearlite layer spacing is the most important factor affecting the strength / hardness change of different coiling temperature of the test steel. The ferrite grain size and the precipitation of nano (V, Cr) C phase are the second.