High temperature tensile and compression experiments on high silicon austenitic stainless steel with different solidification modes and microstructure characteristics were adopted using the Gleeble-3500 thermal simulation machine.The JMatPro software,OM(optical microscope),SEM/EDS(scanning electron microscope/energy dispersive spectrometer)and EPMA(electron probe),were used to studied the thermoplastic variation of high silicon austenitic stainless steel.The results show that the as-cast 6.0 wt.％Si samples solidified in FA mode(with ferrite as the first precipitated phase)have the worst thermo-plasticity,due to the existence of precipitated phase and Weistier-like structure.After homogenization at 1150℃×12h,the solo austenitic structure of 6.0 wt.％Si samples was formed with the section shrinkage reached 76％and elongation 13％.The tensile fracture shows the ductile fracture characteristics and the thermo-plasticity were significantly improved.After the 6.0 wt.％Si sample was homogenized at 1 200 ℃ × 12 h,a large amount of high temperature δ ferrite precipitates again,and the thermo-plasticity decreases significantly as well the fracture took on the characteristics of inter-granular fracture.Combined with hot compression experiments,DRX(dynamic recrystallization)is favored when a moderate amount of elliptical high-temperature δ ferrite is present in the 6.0 wt.％Si specimen.
high silicon austenitic stainless steelδ ferritehomogenization treatmentthermoplasticitysecondary precipitation
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