New Trends in Advanced High Strength Steel Developments for Automotive Application

Abstract

The body design with light weight and enhanced safety is a key issue in the car industry. Corresponding to this trend, POSCO is developing various automotive steel products with advanced performance. Conventional advanced high strength steels such as DP and TRIP steels are now expanding their application since the steels exhibit higher strength and ductility than those of conventional solution and precipitation strengthened high strength steels. Efforts have been made to enhance the mechanical performance of these steels such as ductility, hole expansion ratio, deep drawability, etc. Current research is focused on development of extra- and ultra-AHSS. Extra-AHSS are designed to utilize nano-scale retained austenite embedded in fine bainite and martensite. Ultra-AHSS are designed to have austenite as the major phase, and the ductility is enhanced primarily by continuous strain hardening generated during forming. These steels including extra- and ultra-AHSS are believed to be the next generation automotive steels which will replace the existing high strength steels due to their extremely high strength and ductility combinations.

Twin Roll Casting of Steels: An Overview

“…Highmanganese twinning-induced plasticity (TWIP) steels meet these requirements due to their extraordinary combination of specific strength, high ductility and high work-hardening rate. 39,40) However, the wide use of these steels for industrial applications is limited due to their complex and expensive production processes. TRC is a promising alternative approach for fabrication of this class of materials.…”

Ti/Al Multi-Layered Sheets: Accumulative Roll Bonding (Part A)

“…There are numerous approaches to obtain materials with a high specific strength. On the one hand, novel steels are developed to complement the most dominant class of structural materials and to extend their field of usability to light weight applications [1][2][3]. On the other hand, the "classic" light weight materials for structural applications with densities below 4.5 g/cm 3 , such as Ti, Al, Mg and their alloys, are optimized with respect to strength.…”

“…On the one hand, novel steels are developed to complement the most dominant class of structural materials and to extend their field of usability to light weight applications [1][2][3]. On the other hand, the "classic" light weight materials for structural applications with densities below 4.5 g/cm 3 , such as Ti, Al, Mg and their alloys, are optimized with respect to strength. For this purpose, various means are utilized, including alloy design and the development of novel processing techniques [4][5][6].…”

Effects of Ar and He on Microstructures and Properties of Laser Welded 800MPa TRIP Steel

“…The excellent mechanical properties of TRIP steel mainly contribute to the ferrite matrix, for ductility, bainite, for strength, and retained austenite, for uniform elongation produced by martensite transformation from austenite when subjected to external tensile stress. For the sake of the superior properties of TRIP steel, thinner steel sheets can be adopted for the same strength requirement to reduce the vehicle weight but improve the vehicle performance at the same time [2][3][4][5].…”