临界区热处理工艺对低合金可膨胀管材组织性能的影响

摘要

采用光学显微镜、扫描电镜、透射电镜和X射线衍射等方法研究了临界区热处理工艺对一种低合金可膨胀管材组织性能的影响。结果表明，不同工艺条件下，试验钢的组织主要为铁素体+贝氏体+M/A组织。当加热温度从750℃升高至840℃时，组织粗化， M/A组织体积分数增加及A比例的降低，导致试样强度出现峰值，屈强比和冲击韧性不断降低，均匀延伸率和n不断升高。研究发现，临界区加热温度为780～810℃时试验钢具有良好的综合性能。%In this article, the Influence of different critical zone heat treatment on microstructure and properties of expandable low-alloy tube were investigated by means of optical microstructure, scanning electronic microscope (SEM), transmission electron microscope (TEM), X-ray diffraction and mechanical tests. The results showed that the microstructure of test steel is composed of ferrite, bainite and martensite /austenite (M/A) phases. When the heating temperature increases from 750 ℃to 840℃, the microstructure coarsen, the fraction of M/A phases increase and A proportion reduces, which results in the peak strength appear, the yield ratio and impact toughness decrease gradually, and the uniform elongation and n value constantly increase. It found that the test steel is with good comprehensive properties, when the heating temperature is 780~810℃at critical zone.