Enhancing strength and thermal stability of TWIP steels with a heterogeneous structure

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:720

Article

Xiong, T.^1,2  Zheng, S. J.¹  Zhou, Y. T.¹  Pang, J. C.¹  Jin, Q. Q.¹  Ge, H. L.^1,2  Zheng, X. D.^1,2  Yang, L. X.¹  Beyerlein, I. J.³  Ma, X. L.^1,4 

[1] Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, 72 Wenhua Rd, Shenyang 110016, Liaoning, Peoples R China

[2] Univ Sci & Technol China, Sch Mat Sci & Engn, Hefei 230026, Anhui, Peoples R China

[3] Univ Calif Santa Barbara, Mat Dept, Mech Engn Dept, Santa Barbara, CA 93106 USA

[4] Lanzhou Univ Technol, Sch Mat Sci & Engn, Lanzhou 730050, Gansu, Peoples R China

关键词: TWIP steel;    Heterogeneous structure;    Twin;    High strength;    Thermal stability;   

DOI  :  10.1016/j.msea.2018.02.003

来源: Elsevier

【 摘 要 】

Twinning-induced plasticity (TWIP) steels can exhibit high ultimate strength and ductility, but low yield strength and thermal stability. Here we approach this problem by introducing a heterogeneous microstructure comprised of soft, hard and thermally stable regions in a model composition of Fe-22Mn-0.6 C TWIP steel. This target microstructure is achieved via a three-step processing route: cold rolling to introduce nanotwin bundles, an aging treatment to transform highly defective regions to thermally stable pearlite nano-lamellae, and an annealing step for relatively large, ductile grains. We show that this microstructure generates a good balance between high yield strength, good ductility, high ultimate tensile strength, and good thermal stability. The main deformation mechanism of this unique heterogeneous structure is deformation twinning. The high thermal stability can be attributed to the transformation of the shear bands, introduced by cold rolling, into pearlite during the aging process, and into the composite of nanograined austenite and nanograined cementite formed during the subsequent isothermal annealing.

【 授权许可】

Free