【摘要】 使用凝固过程中施加旋转电磁场并在模壳内表面涂孕育剂铝酸钴相结合的方法,得到了晶粒组织细化至95μm、断面等轴晶比例达到99%以上的K417高温合金铸件。使用电子拉伸试验机、机械伺服疲劳试验机和扫描电镜研究了将晶粒细化至95μm对K417高温合金铸件在室温和中温650℃时拉伸性能和低周疲劳性能的影响。结果表明:在室温和650℃的中温条件下,晶粒细化到95μm可以使K417高温合金铸件的强度、塑性和低周疲劳寿命明显提高;当试验温度从20℃升高到650℃时,K417高温合金铸件的抗拉强度和屈服强度基本保持不变,但其伸长率和断面收缩率却有所降低;在0.3%的总应变控制量下,当试验温度从20℃升高到650℃时,K417高温合金粗晶试样和细晶试样的低周疲劳寿命都有较大幅度的降低。更多还原

【Abstract】 The average grain size of K417 superalloy casting could be refined to 95 μm and the proportion of equiaxed grains could be increased to 99% by imposing rotary electromagnetic stirring after pouring melt to the shell mold with inoculant CoAl2O4.The effect of the grain refinement on the mechanical properties of K417 superalloy castings was investigated.The results show that at 650 ℃,the strength,plasticity and the low cycle fatigue properties of K417 superalloy can be improved significantly by the grain refinement.When the test temperature is increased from 20 ℃ to 650 ℃,the tensile strength and yield strength of K417 superalloy almost keep invariable.However,the plasticity is reduced.Within the total strain of 0.3%,the low cycle fatigue life of K417 superalloy is reduced obviously.更多还原