Studies On The Elevated Temperature Tensile Deformation Behavior Of The Fe-25Cr-35Ni-based Superalloy

By means of OM, SEM and TEM, EBSD, the tensile deformation behavior for Fe-25Cr-35 Ni based superalloy at elevated temperature have been investigated.( The deformation temperature set as 900-1023℃; the strain rate set as from 5×10^-4 to10^-2 s^-1). The forged Fe-25Cr-35 Ni based superalloy was choed as the material of elevated temperature tensile tests. Before the tests, did some solution treatment for the tests material, and the solution treatment temperature set as 1175℃, the time set as 30 min.In the process of elevated temperature tensile test, the yield strength and tensile strength of material decrease with the increasing of temperature. The material possesses best plastic deformation capacity when the deformation temperature was 982℃, and the strain rate was 10^-2 s^-1（Under these conditions the elongation was reached 83.4%）.In the elevated temperature tensile tests, the flow stress decrease with the increasing of temperature and decreasing of strain rate. In the curve of flow stress, there is obvious characteristics of dynamic recrystallization. The result of microstructure analysis shows the degree of dynamic recrystallization incresse with the incressing of temperature, and the dynamic recrystallization crystallites grow larger. And the degree of dynamic recrystallization is higher with smaller strain rate.The result of the fracture at elevated temperature tensile tests shows that the tensile fracture mechanism of Fe-25Cr-35 Ni based superalloy in high temperature is dimple fracture. The fracture is inclined plane, and the stress axis is 45° angle. The dimple grow larger and deeper with increasing of the temperature, and grow smaller and shallower with the increasing of strain rate. In the big dimples on the side wall also appeared serpentine glide.By the elevated temperature tensile tests result show that there is a hyperbolic sine-type equation between deformation activation energy and deformation temperature, and the deformation activation energy is 689.7k J/mol. The following equation could describe the relationship between the flow stress and parameters of high temperature tensile tests:（?）...