回火温度对Q960钢析出物组织特征的影响

Effect of tempering temperature on the structural properties of precipitates in Q960 steel

利用透射电镜、能谱仪(EDX)及多功能内耗仪系统地研究了在相同成分、轧制工艺、淬火工艺和不同回火温度条件下Q960钢组织中析出物的形态、分布和组成,给出了回火温度对析出物组织特征的影响规律.结果显示:回火温度低于400℃时,马氏体内固溶碳量下降趋势较剧烈;回火温度高于400℃时,马氏体内固溶碳量下降非常缓慢.此外,大量细小且平行析出的θ--碳化物溶解并最终被沿马氏体板条界析出的Cr的碳化物代替.随着回火温度的升高,Nb、V和Ti的复合碳氮化物长大,形状也由方形向椭圆形演变.

The morphology,distribution and components of precipitates in Q960 steel under the conditions of the same composition,rolling technology and quenching process but different tempering temperatures were systematically investigated by using transmission electron microscopy（TEM）,energy dispersive X-ray spectrometry（EDX） and a multi-function internal friction device.A law was proposed for describing the effect of tempering temperature on the structure characteristics of the precipitates.It was shown that the decrease of carbon solution content in martensite was greater when the tempering temperature was less than 400 ℃,but it was very slow when the tempering temperature was higher than 400 ℃.In addition,a large number of small parallel θ-carbides dissolved and were finally replaced by Cr carbides which precipitated along martensite lath boundaries.With the tempering temperature increasing,Nb,V and Ti composite carbon and nitrogen compounds grew up and their shape evolved from a square to an oval.