Effect of Nb on Transformation and Property of C-Si-Mn-Cr-Mo High Strength Hot-Rolled DP Steel

Abstract:

Two kinds of C-Si-Mn-Cr-Mo tested steels were used to study the transformation rules and microstructure evolution during thermal mechanical experiment and rolling experiment. Effects of micro alloying element Nb on transformation and propertied were discussed. The result shows that Nb retards ferrite transformation, reduces ferrite volume fraction and refines the ferrite grain size and martensite colony size. After micro-alloying of 0.047wt%Nb, yield strength and tensile strength increase by 145MPa and 135MPa respectively under medium temperature coiling process. YS/TS ratio increases from 0.51 to 0.62, meanwhile, the decrease of elongation is not obvious. The grain refining strengthening and precipitation strengthening of Nb micro-alloying is effective to enhance the strength grade of hot rolled DP steel coiled at medium temperature.

• Periodical: Applied Mechanics and Materials (Volume 510)
• Pages: 110-113
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.510.110
• Online since: February 2014
• Authors: Le Yu Zhou, Bo Jiang, Dan Zhang, Chao Lei Zhang, Ya Zheng Liu
• Keywords: Hot Rolled DP Steel, Mechanical Property, Microstructure Evolution, Nb, Transformation

References

[1] Ma Ming-tu, M. F. Shi. Advanced High Strength Steel and It's Applications in Automobile Industry [J]. Iron and steel, 2004, 39(7): 68-72 (in Chinese).

[2] Tang Di, Mi Zheng-li, Cheng Yu-lai, et al. Technology and Research and Development of Advanced Automobile Steel Abroad [J]. 2005, 40(6): 1-5 (in Chinese).

[3] Cosmo De M, Galantucci L M. Tricarico L. Design of process parameters for dual phase steel production with strip rolling using the finite-element method [J], Journal of Materials Processing Technology, 1999, 92-93: 486-493.

DOI: 10.1016/s0924-0136(99)00241-1

[4] Suwanpinij P, Togobytska N, Prahl U, et al. Numerical cooling strategy design for hot rolled dual phase steel[J]. steel research international, 2010, 81(11): 1001-1009.

DOI: 10.1002/srin.201000091

[5] Dong RF, Li DG, Yan B, et al. Effects of Technological Parameters on Microstructures and Properties of Low Cost Hot Rolled Dual Phase Steel on CSP Line. Journal of Iron and Steel Research, International, 2011, 18(Sl-1): 615-620.

[6] Niakan H, Najafizadeh A. Effect of niobium and rolling parameters on the mechanical properties and microstructure of dual phase steels[J]. Materials Science and Engineering: A, 2010, 527(21): 5410-5414.

DOI: 10.1016/j.msea.2010.05.078