退火工艺对钎具用钢22Si2MnCrNi2MoA带状组织的影响  

Influence of annealing on the banded structure of 22Si2MnCrNi2MoA drill steel

作　　者：朱洪武[1] 刘雅政[1] 徐盛[1] 闫永明[1] 王磊英[2] 黄斌[2] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]西宁特殊钢股份有限公司,西宁810005

出　　处：《北京科技大学学报》2013年第3期312-318,共7页Journal of University of Science and Technology Beijing

摘　　要：使用光学显微镜、扫描也镜和能谱仪等研究了钎具用钢22Si2MnCrNi2MoA动态连续冷却相变规律和退火工艺优化,分析了冷却速度对连续冷却转变曲线和相变组织的影响,探讨了22Si2MnCrNi2MoA钢带状组织成因及改善措施.22Si2MnCrNi2MoA钢具有较高的淬透性,在形变后空冷即可得到贝氏体+马氏体组织.在所选取的温度和时间范围内,710℃退火保温5 h为最优的退火工艺,等温退火并不能改善钢中带状组织的成分不均.带状组织的形成是由于化学元素Si、Mn、Cr、Ni和Mo的偏聚引起的,提高横截面内变形均匀程度对于改善棒材组织均匀性是有利的,但冶金过程成分偏析均质控制才是减轻或消除带状组织成分不均的关键.22Si2MnCrNi2MoA drill steel was tested by optical microscopy,scanning electron microscopy and energy dispersive spectroscopy to study its dynamic continuous cooling phase transformation law and annealing process optimization,analyze the effect of cooling rate on its continuous cooling transformation（CCT） curves and transformation microstructure,and find out the cause of banded structure formation and measures for quality improvement.It is shown that the steel has high hardenability,and a bainite and martensite duplex microstructure is obtained when the hot rolled material is cooled in air after deformation.The optimal annealing process is at 710℃for 5 h.The composition inhomogeneity of the banded structure in the steel cannot be eliminated by isothermal annealing.The banded structure is caused by the segregation of the alloy elements of Si,Mn,Cr,Ni and Mo,and can be weakened by improving the crosssection deformation uniformity of bars.However,the homogeneous distribution of alloy elements in the metallurgical process is the critical way to reduce or eliminate the composition inhomogeneity of the banded structure.

关 键 词：工具钢 微观组织 退火 冷却 相转变 优化 

分 类 号：TG156.2[金属学及工艺—热处理] TG161.1[金属学及工艺—金属学]