热处理工艺对双相等温淬火球墨铸铁组织的影响

摘要

利用扫描电镜分析了热处理工艺对双相ADI(等温淬火球墨铸铁)组织的影响.结果表明:当奥氏体化温度在820～880℃时,随着奥氏体化温度的升高,铁素体的含量逐渐减少,奥氏体的含量逐渐增加,当奥氏体化温度达到880℃时,基本全部奥氏体化.当等温淬火温度为250～370℃时,随着等温淬火温度的升高,组织由细针状铁素体、残余奥氏体及破碎状铁素体转变成大量的羽毛状贝氏体型铁素体、破碎状铁素体和较多的残余奥氏体.当等温淬火时间为30～90 min时,等温淬火时间较短时,组织为少量马氏体、破碎状铁素体、针状铁素体和残余奥氏体,当等温淬火时间超过90 min时,奥氏体容易发生分解,生成铁素体和碳化物.%Scanning electron microscope (SEM) was used to analyze the effects of the heat treatment on the microstmcture of dual Phase ADI.The results show that the content of the ferrite decreases and the austenite increases with the austenitizing temperature increasing in the range of 820-880 ℃.The complete austenitizing temperature ends at 880 ℃.The microstructure turns from fine acicular ferrite,residual austenite and broken-shaped ferrtte into a lot of feathered bainitic ferrite,broken-shaped ferrite and more residual austenite when the austempering temperatures rise in the range of 250-370 ℃.The microstructures were characterized by a small amount ofmartensite,broken like ferrite,acicular ferrite and retained austenite when the austempering time is short as 30-90 min.The austenite was easily decomposed into the ferrite and carbide when the austempering time is more than 90 min.