Challenges in the formability of the next generation of automotive steel sheets

Abstract

Improving strength may lightweight car bodies by thinning the structure gauge while bearing the same crash loads. Development of the third generation advanced high-strength steels aiming to boost material ductility to over 30% total elongation has become the common sense of potential solutions for stamping. Not only total elongation but also several other parameters, involving presswork hardening, anisotropy ratio, strain rate sensitivity, uniform elongation, edge sensitivity and internal stress between phases, are critical in determining the formability under the complex stress and strain distributions during stamping. We clarify here the logic of formability and difficulties in this context of three types of steel: quenching and partitioning, δ-transformation-induced plasticity and medium Mn-TRIP.

Effects of Strain Rate on the Deformation Mechanism of Ultra-high Strength TWIP Steel

“…Qihang PANG, 1,2) Mei XU, 3) Jing GUO, 1,2) * Huan QI, 1,2) Jiaji WANG 2) and Ling YAN 2) 1) School of Materials May 11, 2020) The deformation mechanism of Fe-20Mn-0.6C twinning-induced plasticity (TWIP) steel was studied with respect to different strain rates ranging from 10 − 4 to 10 3 s − 1 . Moreover, the microstructure of the ultra-high strength TWIP steel at each strain rate was characterized by transmission electron microscopy (TEM).…”

“…Moreover, the high strength and negligible low-temperature brittle transformation of TWIP steel make it a promising choice for lightweight automotive applications. [1][2][3] Furthermore, the fabrication and forming process of TWIP steel have garnered much attention due to its excellent plasticity, optimal toughness, and widespread utilization in the automotive industry. [4][5][6] One should note that the typical strain rate of TWIP steel is in the range of 10 − 1 to 10 1 s − 1 .…”

A Study on Potential Strip Shape Control of High‐Strength Steel during Hot Pinch Rolling Process

“…However, the higher the strip strength is required, the more difficulties may happen on the internal stress control. [ 1 ] It will inevitably cause a series of problems on the shape control of the hot rolled strip. At present, HSS such as 510L (the yield strength is about 468 MPa) produced by means of hot rolling presents potential strip shape defect.…”

Improving Hydrogen Embrittlement Resistance of Hot-Stamped 1500 MPa Steel Parts That Have Undergone a Q&P Treatment by the Design of Retained Austenite and Martensite Matrix

“…As a third-generation advanced high strength steel (AHSS), quenching and partitioning (Q&P) steels exhibit an excellent combination of strength and ductility for automotive body lightweighting [1][2][3][4][5][6]. The production of ultimate tensile strength and total elongation has reached over 30,000 MPa % in state-of-the-art Q&P steels [7][8][9].…”