等温淬火对含铬球墨铸铁组织及性能的影响

Effect of austempering process on microstructure and mechanical properties of ductile iron containing Cr

研究了等温淬火工艺对含铬球墨铸铁组织、硬度、冲击性能和耐磨性的影响。结果表明:奥氏体化温度升高,能促进球状石墨长大,增加残留奥氏体含量。淬火后组织主要为球状石墨、针状贝氏体、含铬碳化物及残留奥氏体。当淬火等温温度在240~270℃,随着等温温度升高,试样硬度和耐磨性均降低;在240℃等温淬火时冲击韧度较低,继续升高等温温度,冲击韧度先增大后降低;当试样经910℃×80 min奥氏体化、270℃×180 min等温淬火后,含铬球墨铸铁的硬度可达54.1 HRC、冲击韧度αk可达8.1 J·cm^(-2),有较好的耐磨性。

Effects of austempering process on microstructure,hardness,impact toughness and wear resistance of austempered ductile iron containing Cr were investigated.The results show that increassing the austenitizing temperature can promote the growth of spheroidal graphite and increase the content of residual austenite.The microstructure is mainly composed of spheroidal graphite,acicular bainite,carbides containing chromium and residual austenite.As the austempering temperature increasing within 240-270 ℃,both of the hardness and wear resistance decrease,however the value of impact toughness is enhanced first and then decrease.When the samples austenitized at 910 ℃ for80 min and austempered at 270 ℃ for 180 min,the mechanical properties of the austempered ductile iron containing chromium are preferable,the hardness is 54.1 HRC,impact toughness is 8.1 J·cm^（-2）,and the wear resistance is excellent.