Cold-forming effect on stainless steel sections: Fid-Bau Portal

Cold-forming effect on stainless steel sections

Howlader, Milon K. / Marik, Jan / Jandera, Michal

Abstract Stainless steel exhibits greater extent of strain hardening than carbon steel, which leads to significant change in mechanical properties (increase in yield strength and decrease in ductility) of the stainless steel material due to the cold forming process. These changes of the mechanical properties depend mainly on the magnitude of residual stresses and equivalent plastic strain induced by the cold working. This paper presents an analytical model for determining the residual stresses and the corresponding plastic strain by means of Maple software simulating the cold forming process. The analytical model in Maple is validated by the previous numerical and experimental data of cold formed sheets. The increased material properties are determined after cold forming for corners and flat faces of sections considering the residual stresses and plastic strain and validated with the previous test results. For the prediction of the increased yield strength, new material properties with respect to the induced plastic strain based on tests are set for cold bending process in the analytical model. The analysis for the increased yield strength is calculated for four stainless steel grades, i.e., austenitic (1.4404), ferritic (1.4003), lean-duplex (1.4162) and duplex (1.4462) and the results are compared with the previous predictive models of the strength increase.