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利用Gleeble-1500热模拟试验机研究镍基高温合金K403在应变速率为0.01~10 s-1、温度为850~1 000℃条件下的高温拉伸变形行为,利用光学显微镜、扫描电镜、透射电镜等手段,分析拉伸变形后的显微组织及高温断裂机制。结果表明:随应变速率的增大,合金的峰值应力和断裂应力增大,断面收缩率和断裂应变则减小;而随变形温度的升高,合金的峰值应力和断裂应力降低,断面收缩率和断裂应变增大;850℃拉伸后变形组织中存在大量的位错胞状结构,随着变形温度的升高,变形组织中的位错密度减小;拉伸断口呈枝晶组织断裂特征,随着变形温度的升高,合金断裂方式由准解理断裂向沿晶断裂转变。
The tensile behavior of high temperature nickel-base superalloy K403 at high strain rate of 0.01 ~ 10 s-1 and temperature of 850 ~ 1 000 ℃ was investigated by Gleeble-1500 thermal simulator. The microstructures of K403 were studied by optical microscopy, scanning electron microscopy, transmission electron microscopy And other means to analyze the tensile deformation of the microstructure and high temperature fracture mechanism. The results show that with the increase of strain rate, the peak stress and the fracture stress of the alloy increase, the reduction of area and the fracture strain decrease. With the increase of the deformation temperature, the peak stress and the fracture stress of the alloy decrease and the reduction of area And the strain at break increased. After deformation at 850 ℃, a large number of dislocations were found in the deformed structure. With the increase of the deformation temperature, the dislocation density in the deformed structure decreased. The tensile fracture was characterized by the dendrite fracture, With the increase of deformation temperature, the mode of alloy fracture changes from quasi-cleavage fracture to intergranular fracture.