New Generation Press Hardening Steels with Tensile Strength of 1.7-2.0 GPa and Enhanced Bendability
New Generation Press
Hardening Steels with Tensile Strength of 1.7-2.0 GPa
and Enhanced Bendability
Jianfeng
Wang1*, Qi Lu1, Xiaochuan Xiong2
and Hongliang Yi2,3
Abstract
PHS applications predominately use 22MnB5 AlSi coated in the automotive industry. This material is expensive and has a limited supply chain. Increasing the tensile strength and bendability of the PHS material will enable lightweighting while maintaining crash protection. In this paper, novel press hardeing steel is investigated and properties are compared to 22MnB5. The new uncoated PHS steel, 25MnCr, has increased carbon, with chromium and silicon additions for oxidation resistance. Its UTS of 1.7 GPa with bending angle above 55° at 1.4mm thickness improves upon the 22MnB5 grade. This steel is not pre-coated, is oxidation resistant at high temperature, thus eliminating the need for AlSi or shot blasting post processing to maintain surface quality. Microstructural mechanisms used to enhance bendability and energy absorption are discussed for the novel steel. Performance evaluations such as: weldability, component level crush and intrusion testing and corrosion, are conducted on samples from industrial coils.
Keywords:
Press hardening
steel, Bendability, Martensite, Fracture