Effect of solution temperature on microstructure and low cycle fatigue properties of S32750 duplex stainless steel
The microstructure and low cycle fatigue properties of five kinds of solid solution temperature test steels were studied by optical microscope,electron backscatter diffraction,microhardness test,tensile and fatigue tests.The results show that the yield strength and tensile strength of the test steel are increased by 41 MPa and 31.5 MPa,respectively,and the low cycle fatigue life is prolonged by 85％when the solution temperature is increased from 1 050 ℃ to 1180 ℃.The content of α phase in the tested steel increases from 46.5％to 58.9％and the main elements in two phases are redistributed result from the increase of solution temperature,the increase of ferritic microhardness from 300 to 324 is caused by the increase of Ni and N in α phase,which is one of the reasons for the increase of fatigue lifetime of the test steel;with the increase of solution temperature,the local misorientation in the α phase decrease significantly,and the α phase can withstand more stress during the process of fatigue experiment,it is another important reason for the increase of low cycle fatigue lifetime.
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