Comparison of stampability between a microalloyed steel and a carbon-manganese steel

Abstract

Aiming to meet the demand for greater forming capacity while maintaining high levels of mechanical resistance, this study aims to carry out a comparison between the chemical composition, microstructure, mechanical properties and stampability of a Carbon-Manganese steel and a high-strength, low-alloy steel.(ARBL) with a minimum yield limit of 350 MPa, since numerous parts manufactured with this class of steel have high drawing even with hole expansion, as is the case of the part object of this study.By adjusting the chemical composition and thermomechanical treatment for better stability of mechanical properties and thickness, it was possible to obtain good formability of the microalloyed steel, whose mechanical properties were found to be (resistance limit 472 MPa, yield limit 404 MPa, base elongation 50 of 35% and hardening exponent n of 0.16) and microstructure with grain size 5, globulized non-metallic inclusions type D level 1 and fine series in addition to spheroidized carbides uniformly distributed in the ferritic matrix, whereas Carbon-Manganese steel with resistance limit and similar flow presented comparatively worse results in relation to formability (resistance limit 508 MPa, yield limit 398 MPa, base elongation 50 of 32% and hardening exponent n of 0.12), microstructure with grain size 9, inclusions not elongated metallic type C level 1 fine series and lamellar pearlite fraction which, morphologically, is not the most suitable microstructure for forming processes.In view of the above, the development of the work made it possible to increase the formability of the steel, facilitating the stamping of the studied piece and without the presence of cracks, even in sections of high conformation/hole expansion, as was possible to observe in the comparative photos of the pieces stamped with the steel Carbon-Manganese and Micro alloy designed for better formability.