This is the published version Cai, Minghui, Ding, Hua, Zhang, Jiansu, Li, Long and Tang, Zhengyou 2009, Deformation and fracture characteristics of ferrite/bainite dual-phase steels, Cailiao yanjiu xuebao/Chinese journal of materials research, vol. 23, no. 1, pp. 83-88. Available from Deakin Research Online http://hdl.handle.net/10536/DRO/DU:30047768 Every reasonable effort has been made to ensure that permission has been obtained for items included in Deakin Research Online. If you believe that your rights have been infringed by this repository, please contact drosupport@deakin.edu.au Copyright: 2009, Zhongguo Kexueyuan Jinshu Yanjiusuo

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Deformation and fracture characteristics of ferrite/bainitedual–phase steels

CAI Minghui1 DING Hua1∗ ZHANG Jiansu2 LI Long3 TANG Zhengyou1

1.School of Materials and Metallurgy, Northeastern University, Shenyang 1100042.Technology Center, Baoshan Iron & Steel Group Co., Shanghai 201900

3.National Institute for Materials Science, Japan, Tsukuba 305–0047Manuscript received April 25, 2008; in revised form June 5, 2008.* To whom correspondence should be addressed, Tel:(024)83686458, E–mail: hding@263.net

ABSTRACT The deformation and fracture characteristics of a low carbon Si–Mn steel with fer-rite/bainite dual–phase structure were investigated by thermo–mechanical controlled process (TMCP).The results showed that the curves of the instantaneous work–hardening factor n∗ value versus true strainε are made up with three stages during uniform plastic deformation: n∗ value is relatively higher at stage�, decreases slowly with � in stage �, and then decreases quickly with ε in stage �. Compared tothe equiaxed ferrite/bainite dual–phase steel, the quasi–polygonal ferrite/bainite dual–phase steel showshigher tensile strength and n∗ value in the low strain region. The voids or micro–cracks formed not only atferrite–bainite interfaces but also within ferrite grains in the necked region, which can improve the propertyof resistance to crack propagation by reducing local stress concentration of the crack tips.

KEY WORDS metallic materials, ferrite/bainite dual–phase steel, uniaxial tension, deformation be-havior, fracture characteristics

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