Grain size refinement and effect on the tensile properties of a novel low-cost stainless steel

In this study, a novel 20LH5 austenitic stainless steel (AUSS) with various grain sizes was produced. The purpose of this paper is to analyse the effect of the grain size on the tensile fracture morphology and mechanical properties. After a phase reversion process (large ductility cold rolling and annealing), stainless steels with different microstructures comprising coarse grains (CGs) (similar to 9.2 mu m) to fine grains (FGs) (similar to 2.1 mu m) to ultrafine grains (UFGs) (similar to 1.4 mu m) were observed. Tensile tests were then carried out to verify the grain refinement strengthening mechanism. The results show that the mechanical properties in materials that possess UFGs reached a tensile strength of similar to 1090 MPa, a yield strength of similar to 530 MPa and an elongation rate of similar to 47%, which is much better than those of materials with FGs, CGs, and most 300 series AUSSs. Furthermore, the voids in UFG AUSSs were densely distributed and finer than those in the other two counterparts. This indicates that a decreased grain size contributed to a decreased dimple size; that is, the ductility and strength were increased. (C) 2019 Elsevier B.V. All rights reserved.