Effect of cold working on mechanical properties of pure-304L stainless steel with variable temperature - an experimental study

Abstract

ABSTRACT In the current investigation, cold work influence on mechanical strength, microstructure, hardness and ductile to brittle transition (DBT) in pure (P) 304 L-stainless steel (SS) (with ultra-low content of sulphur (0.001%) and phosphorus (nil) at several levels of cold work (5%, 10%, 20% and 30%) are reported, which provide valuable information regarding beneficial effects of reduced level of sulphur for the material selection in structural design. The cold work results in dual-phase (γ +) with distinct values of dislocation densities and grain size that are used in the modified Hall-Petch equation to obtain the corresponding change in yield strength. Cold working up to 30% increased yield strength () from 280 to 900 MPa, whereas ultimate tensile strength (), increased from 620 to 950 MPa, i.e. an increase of 34.73%. The hardness values increased from 172 to 360 Hv, i.e. an enhancement of 110.5% for a cold work of 30%. The material showed a remarkable enhancement in the impact energy absorption from 200 to 390 J for a temperature change from 77 to 473 K. It is observed that cold working at 5% level reduces the impact energy absorption from 390 to 250 J, i.e. reduction of 35.89% at 298 K. The value of impact energy absorbed by P-304 L-SS was 37% higher than the commercial grade 304 L-SS (sulphur (0.03%), phosphorous (0.04%). The study succinctly brings out the importance of reduced content of sulphur and phosphorus in obtaining superior mechanical properties through cold work.