蠕墨铸铁凝固过程组织偏析的均匀化热处理研究

Investigation on Homogenization Heat Treatment of Structure Segregation in Vermicular Graphite Iron Solidification Process

研究了蠕墨铸铁中最后凝固区(LTF)元素偏析导致其基体组织异常的机理,采用均匀化退火热处理技术降低元素偏析,提高组织均匀性,使材料综合性能得到提升。研究表明:蠕墨铸铁凝固过程中LTF区Mo元素富集,使材料基体为贝氏体、马氏体、珠光体和铁素体混合基体组织;通过均匀化定量珠光体热处理技术,消除由元素偏析引起的异常网状结构,且珠光体体积分数控制在35%。

An investigation was conducted on the mechanism of elements segregation in the last solidifying zone(LTF)causing abnormal matrix structure in vermicular graphite iron,and using homogenizing annealing heat treatment technique to reduce elements segregation,improve structure uniformity to elevate comprehensive properties of the material.The investigation showed:the element Mo was enriched in LTF zone during solidification process of vermicular graphite iron,causing matrix structure being mixed matrix consisted of bainite,martensite pearlite and ferrite.By using homogenizing quantitative pearlite heat treating technique,eliminated the abnormal net structure caused by elements segregation,and controlled the pearlite volume proportion at 35%.