热处理工艺对20Cr1Mo1VTiB螺栓钢持久性能的影响

 为了更好地验证20Cr1Mo1VTiB螺栓钢在国家标准和俄罗斯标准热处理工艺下的持久性能,采用SEM、TEM等手段研究了两种标准的热处理工艺对20Cr1Mo1VTiB螺栓钢组织及持久性能的影响。结果表明,相对于低温淬火+低温回火(俄罗斯标准)工艺,高温淬火+高温回火(国家标准)的热处理工艺生产的20Cr1Mo1VTiB具有更高的持久性能稳定性。俄罗斯标准工艺淬火温度低,未溶的块状富钛碳化物数量多、尺寸大,并且贝氏体内分布大量方(菱)形TiC,促进了蠕变孔洞的形成,因此持久强度下降速率更快。国家标准工艺淬火温度高,富钛碳化物回溶充分,数量少、尺寸小,回火过程析出细小的颗粒状VC,热稳定性较高,具有更高的持久强度。从持久性能角度,选用国家标准工艺热处理更加合理。

Effect of heat treatment process on creep-rupture property of 20Cr1Mo1VTiB bolt steel

In order to verify the creep-rupture performance of 20Cr1Mo1VTiB bolt steel under the national and Russian standard heat treatment processes,the effects of two standard heat treatment processes on the structure and creep-rupture properties of 20Cr1Mo1VTiB bolt steel were studied by means of SEM and TEM. The results show that high-temperature quenching+high-temperature tempering (GB) has higher durability and stability than low-temperature quenching+low-temperature tempering (Russian standard) process. The Russian standard process has a low quenching temperature,a large amount of square (diamond) undissolved massive Ti-rich carbides with a large size distributed in the bainite,which promotes the formation of creep holes,and leading to the rapid decrease of creep-rupture strength. The Chinese standard process has a high quenching temperature,most of the Ti-rich carbides were dissolved into the matrix,lot of fine particles of VC with good thermal stability precipitated during tempering,and the creep-rupture strength was improved. Thus,it was more reasonable using high temperature quenching and tempering.