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| Microstructures and mechanical properties of ferrite-based lightweight steel with different compositions |
| Reng-chong Xu1,2,Yan-lin He1,2,Hu Jiang1,2,Hua Wang1,3,Na-qiong Zhu1,2,Xiao-gang Lu1,4, Lin Li1,2 |
1 School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China
2 State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072, China
3 Instrumental Analysis & Research Center, Shanghai University, Shanghai 200072, China
4 Materials Genome Institute, Shanghai University, Shanghai 200444, China |
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Abstract The microstructures and mechanical properties of ferrite-based lightweight steel with different compositions were investigated by tensile test, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermodynamic calculation (TC). It was shown that the ferrite-based lightweight steels with 5 wt.% or 8 wt.% Al were basically composed of ferrite, austenite and ��-carbide. As the annealing temperature increased, the content of the austenite in the steel gradually increased, while the ��-carbide gradually decomposed and finally disappeared. The mechanical properties of the steel with 5 wt.% Al and 2 wt.% Cr, composed of ferrite and Cr7C3 carbide at different annealing temperatures, were significantly inferior to those of others. The steel containing 5 wt.% Al, annealed at 820��C for 50 s then rapidly cooled to 400��C and held for 180 s, can obtain the best product of strength and elongation (PSE) of 31242 MPa��%. The austenite stability of the steel is better, and its PSE is higher. In addition, the steel with higher PSE has a more stable instantaneous strain hardening exponent (n value), which is mainly caused by the effect of transformation induced plasticity (TRIP). When the ��-carbide or Cr7C3 carbide existed in the microstructure of the steel, there was an obvious yield plateau in the tensile curve, while its PSE decreased significantly.
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Received: 08 October 2016
Published: 07 July 2017
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| Fund:Shanghai Municipal Science and Technology Commission |
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Corresponding Authors:
Yan-lin HE
E-mail: ylhe@t.shu.edu.cn
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2017, Vol. 24 
