Dependence of plastic strain and microstructure on elastic modulus reduction in advanced high-strength steels

Increase in the use of the advanced high-strength steels (AHSS) is an interesting alternative to automotive industry to reduce vehicle weight and fuel consumption. However, it has been limited due to challenges in formability, tool life, and springback. The springback is pointed in the literature as one of the challenges that involves the mass production of structural components and the aspects that shows influence are still not fully understood. There is still a gap in the literature to analyze the elastic modulus variation during unloading (also called chord modulus). Therefore, this study experimentally examines the variation of elastic modulus in conjunction with plastic strain and initial microstructure of various automotive steels. For all AHSS, it was found that the elastic modulus decreases during loading and unloading with respect to plastic strain. It was observed that the microstructure of AHSS greatly affects the reduction in elastic modulus upon deformation. It was also found that the degradation of elastic modulus also affected by the anisotropy of the material.