热处理对RE-Nb变质无限冷硬铸铁组织与性能的影响

Effect of Heat Treatment on Microstructures and Properties of RE-Nb Modification Chilled Cast Iron

采用扫描电镜、X射线衍射仪等分析手段,研究了热处理工艺对离心铸造变质无限冷硬铸铁轧辊组织和性能的影响。结果表明,变质无限冷硬铸铁轧辊的铸态组织是贝氏体+碳化物+少量马氏体+极少量残余奥氏体+蠕虫状石墨。经热处理后,变质无限冷硬铸铁轧辊组织中少量的残余奥氏体几乎消失,贝氏体数量明显增多。随着回火温度升高,试样的硬度降低,冲击韧度先升高后下降。250℃回火时,试样具有最优的综合力学性能。

Effects of heat treatment on microstructures and properties of modification chilled cast iron roll were investigated by scanning electron microscopy（SEM）,X-ray diffraction（XRD）analysis.The results show that the as-cast microstructure of modification chilled cast iron roller is composed of bainite,carbide,a small amount of martensite,trace retained austenite and vermicular graphite.After heat treatment,retained austenite almost disappears,and bainite content is increased obviously.Along with the increase of tempering temperature,the hardness of the sample prepared is reduced,and impact toughness is increased firstly and then decreased.Desirable comprehensive mechanical properties of the specimen tempered at 250℃can be obtained.