Influence of Deformation Temperature on Hot Ductility of As-cast Austenitic Stainless Steel

The influence of deformation temperature on the hot ductility of as-cast and hot-rolled austenitic stainless steel Cr15Mn9Cu2NiN is investigated via high-temperature tensile tests.Results show that at 1 250℃,reduction of areas(RA) in both as-cast and hot-rolled specimens are higher than 85%.As the deformation temperature decreases,hot ductility of as-cast specimens drops rapidly while there is no obvious variation for that of hot-rolled specimens.As the deformation temperature decreases to 900℃,RA of as-cast specimens is just around 45%.Analyses suggest that microstructures in as-cast specimens are coarse columnar grains,deformation coordination ability of which falls fast with decreasing deformation temperature,leading to strain concentration at grain boundary or phase boundary,and then resulting in crack nucleating and rapid reduction of hot ductility.For hot-rolled specimens,the microstructures are homogeneous and fine equiaxed grains with excellent ability of deformation coordination; during deformation,the strain uniformly distributes in all the grains,which brings about higher hot ductility.