Tensile properties of cold-rolled TWIP-cored three-layer steel sheets

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• 作者：Jaeyeong Park^a ; Minju Kang^a ; Seok Su Sohn^a ; Jung-Su Kim^a ; Hyoung Seop Kim^a ; Won Tae Cho^b ; Sunghak Lee^a ; ^{shlee@postech.ac.kr}
• 关键词：Twinning induced plasticity (TWIP) steel ; Low-carbon (LC) steel ; Interstitial-free (IF) steel ; TWIP-cored three-layer steel sheet ; Tensile test ; Yield point phenomenon
• 刊名：Materials Science and Engineering: A
• 出版年：2017
• 出版时间：16 February 2017
• 年：2017
• 卷：686
• 期：Complete
• 页码：160-167
• 全文大小：2574 K
• 卷排序：686

文摘

In this study, TWIP-cored three-layer steel sheets containing thin surface layers of low-carbon (LC) or interstitial-free (IF) steel were fabricated by solid-state hot-roll-bonding followed by cold-rolling. Interfaces were well bonded without any pores or voids, which indicated a successful fabrication of the TWIP-cored sheets. According to the tensile test results, both strength and elongation of TWIP-cored sheets increased proportionally with the volume fraction of TWIP-cored region, and were well matched with strength and elongation calculated by a rule of mixtures. However, yield point (YP) was observed in most of TWIP-cored sheets as well as mono-layer TWIP and LC sheets. After the sheets were quenched from 830 °C, the YP disappeared because the dislocation density was greatly increased by effects of thermal stresses formed during the rapid cooling. A bainitic microstructure, which was generally characterized by the continuous yielding, was formed along TWIP/LC or TWIP/IF interfaces, and also beneficially influenced to the elimination of YP. These TWIP-cored sheets covered a wide range of yield and tensile strength and ductility levels requiring in automotive steel sheets by controlling the volume fraction of TWIP-cored region, and thus present new applications to multi-functional automotive steel sheets.