离心铸造LGJW20钢结硬质合金热疲性能研究

在自约束型热疲劳试验机上对LGJW20钢结硬质合金进行了热疲劳试验,借助金相分析、扫描电镜(SEM)、能谱分析(EDS)等方法观察了合金的显微组织,重点研究了LGJW20的热疲劳性能表现,分析了热处理工艺对合金热疲劳性能的影响。结果表明:合金中硬质相主要由鱼骨状共晶碳化物、网状二次碳化物及大块状碳化物组成;合金的热疲劳裂纹在缺口根部萌生,以一条主裂纹形式沿碳化物扩展;合适的热处理工艺能提高基体的高温屈服强度,改善合金的组织结构,提高了合金的热疲劳性能。LGJW20经过980℃淬火、200℃回火处理后热疲劳性能最佳。

Research on Thermal Fatigue Properties of LGJW20 Steel Bonded Carbide by Centrifugal Casting

The thermal fatigue tests of LGJW20 steel bonded carbide were performed on self-restraint thermal fatigue testing machine.By means of optical microscope,scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS),the microstructure of alloy was observed.The thermal fatigue behavior of LGJW20 was studied.The effect of heat treatment on thermal fatigue properties of the alloy was analyzed.The results show that the hard phases in the alloy are mainly composed of fishbone-like eutectic carbide,network secondary carbide and massive carbide.The thermal fatigue cracks are initiated at the notch root and propagated along the carbide network in the form of a main crack.The appropriate heat treatment process can improve the high temperature yield strength and microstructure of the alloy,so the thermal fatigue properties are improved.The thermal fatigue properties of LGJW20 are the best when quenched at 980℃ and tempered at 200℃.