Investigation on Mechanical Properties and Oxidation Behavior of 1.2 and 1.7 GPa Grades Coating-Free Press-Hardened Steels

Al-Si-coated boron-alloyed steels are the most widely used press-hardened (PHSs), which offers good oxidation resistance during hot forming due to presence of near eutectic Al-Si coating. In this study, a recently developed novel un-coated resistant PHS, called coating-free PHS (CF-PHS), is introduced as an alternative commercial coated PHSs. With tailored additions Cr, Mn, and Si, new steel demonstrates superior with sub-micron oxide layer after conventional stamping process. Hence, it does not require shot blasting before subsequent welding E-coating Two CF-PHS grades have been ultimate tensile strengths approximately 1.2 1.7 GPa, respectively. Both total elongation 8–9%, exceeding corresponding (1.0 GPa/6–7%, 1.5 GPa/6–7%). Furthermore, bendability was similar grades. On other hand, performance evaluations relevant automotive applications, such weldability, E-coat adhesion, tailor-welded stamp door ring, were also conducted on satisfy requirements manufacturing.