34CrNi3MoV钢组织细化工艺的研究

均质化退火、完全退火，对减轻34CrNi3MoV钢的带状组织、消除混晶具有理论意义和实用价值。应用OLS4000激光扫描共聚焦显微镜、JEM-2100高分辨电子显微镜对34CrNi3MoV钢组织结构进行观察。利用α′γ循环相变的过程对34CrNi3MoV钢在800，900 ℃分别进行3次细化晶粒的正火，统计各个温度、各个正火次数下的晶粒直径分布情况。结果表明，800 ℃下随着正火次数的增多，晶粒细化效果明显；而在900 ℃下却没有这样的细化趋势。经过调质处理的预备热处理+一次正火后的试样与原始管坯试样的力学特性相比，低温韧性大大提高。

Microstructure of refined 34CrNi3MoV steel

Banded structure and mixed crystal in 34CrNi3MoV steel being reduced and eliminated through homogenization annealing and full annealing have theoretical significance and practical value.The microstructure of 34CrNi3MoV steel was investigated using laser scanning confocal microscope(OLS4000),and transmission electron microscope(JEM-2100).Based on the thermo-cycle refining processing,three times grain refinement normalizing were performed at the temperature of 800 ℃ and 900 ℃,respectively,then the distribution of grain diameters at different temperatures and normalized frequency was counted.The results show that,increasing the times of normalizing,the percentage of small size grains increases at the temperature of 800 ℃,while at the temperature of 900 ℃,this phenomenon does not exist.Comparing with the original tube specimen,the low temperature toughness of the sample is greatly improved.