Effects of Intercritical Annealing Temperature on Mechanical Properties of Fe-7.9Mn-0.14Si-0.05Al-0.07C Steel

Materials

卷:7

Yandong Liu¹  Liang Zuo¹  Yongfeng Shen¹  Lina Qiu¹  Xin Sun²  Xianming Zhao³ 

[1] Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, Shenyang 110004, China;

[2] Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, USA;

[3] The State Key Lab of Rolling & Automation, Northeastern University, Shenyang 110004, China;

关键词: medium Mn steel;    TRIP effect;    austenite;    strength;    ductility;   

DOI  :  10.3390/ma7127891

来源: DOAJ

【 摘 要 】

A medium Mn steel has been designed to achieve an excellent combinationof strength and ductility based on the TRIP (Transformation Induced Plasticity) conceptfor automotive applications. Following six passes of hot rolling at 850 °C, theFe-7.9Mn-0.14Si-0.05Al-0.07C (wt.%) steel was warm-rolled at 630 °C for seven passes and subsequently air cooled to room temperature. The sample was subsequently intercritically annealed at various temperatures for 30 min to promote the reverse transformation of martensite into austenite. The obtained results show that the highest volume fraction of austenite is 39% for the sample annealed at 600 °C. This specimen exhibits a yield stress of 910 MPa and a high ultimate tensile stress of 1600 MPa, with an elongation-to-failure of 0.29 at a strain rate of 1 × 10−3/s. The enhanced work-hardening ability of the investigated steel is closely related to martensitic transformation and the interaction of dislocations. Especially, the alternate arrangement of acicular ferrite(soft phase) and ultrafine austenite lamellae (50–200 nm, strong and ductile phase) is the key factor contributing to the excellent combination of strength and ductility. On the other hand, the as-warm-rolled sample also exhibits the excellent combination of strength and ductility, with elongation-to-failure much higher than those annealed at temperatures above 630 °C.

【 授权许可】

Unknown