Estimation of Strain-Hardness Correlation in Cold-Forged Austenitic Stainless Steel

Abstract:

The paper presents selected aspects of analysis cold micro-forging process of a screw made of austenitic stainless steel, concerning relation between strain and hardness. Strain hardening character of a material in consecutive forming operations was analyzed experimentally by the measurement of hardness distribution made on longitudinal axial sections of screws. The relationship between hardness and effective strain (hardness curve) was determined, which made it possible to obtain strain distributions in different regions of a material subjected to cold deformation on the basis of strain distribution numerically estimated with FEM simulation performed using QForm2D/3D commercial software. Conclusions were formulated concerning strain inhomogeneity and strain-hardening intensity with respect to the correlation between strain and hardness. It was also concluded, that nonuniformity of hardening rate in a bulk can lead to local variations in flow stress and eventually, to occurrence of the metal flow related defects, which was illustrated with a case study of cold heading of self-tapping screw of AISI 304Cu stainless steel, with large head diameter to shank diameter ratio. In order to validate the obtained results, the same method was used for analysis of hardness development in steel 19MnB4.

• Periodical: Key Engineering Materials (Volumes 622-623)
• Pages: 179-185
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.622-623.179
• Online since: September 2014
• Authors: Piotr Skubisz*, Maciej Rumiński, Łukasz Lisiecki
• Keywords: Austenitic Stainless Steel, Cold Heading, FEM Simulation, Hardness, Micro Forging

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