Continuous Cooling Transformation Diagram and Properties of Hot Forming Steel

Abstract:

Continuous cooling transformation (CCT) diagram of steel 22MnB5 was studied using dilatometer method. The influence of the hot forming process parameters, such as the heating temperature and holding time on the mechanical properties and microstructure of stamped parts was analyzed by tensile tests and the metallographic observation on the parts with various processing parameters. The microstructural evolution obtained from the dilatometer samples reveals that the cooling rates not smaller than 20K/s induced fully martensitic microstructure. As the cooling rate decreasing, more ferrite and pearlite or more bainitic microstructure forms. Tensile tests results show an excellent tensile strength and ductility combination of 22MnB5. The tensile strength and yield strength reach 1500MPa and 1200MPa respectively, with total elongation of around 10%.

• Periodical: Applied Mechanics and Materials (Volumes 152-154)
• Pages: 585-588
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.152-154.585
• Online since: January 2012
• Authors: Mei Zhang, Qing Shan Li, Kun Han, Chao Bin Huang, Ru Yi Wu, Ren Yu Fu, Lin Li, Zi Wan, Bao Liang Sun
• Keywords: 22MnB5 Steel, CCT Diagram, Mechanical Property, Transformation Characteristics

References

[1] D.W. Fan, H.S. Kim, and B.C. De Cooman, A review of the physical metallurgy related to the hot press forming of advanced high strength steel, Steel Research Int. Vol. 80 n3 (2009) 241-248.

[2] J. Maki, Properties of Aluminum-coated Steels for Hot-forming, Nippon Steel Technical Report, 2003, No. 88.

[3] L. Wang, X.F. Yang, and J.X. Lu, Lightweight Automobile and high strength steel application, In: Proceedings of 15th annual conference on automotive materials, (2007), SAE China, (2007).

[4] M. Zhang, K. Han, B.L. Sun, G.J. Shao, L. Wang, L. Li, Effect of Hot Press Forming Process on Microstructure and Mechanical Properties of Boron Steels, ICAS 2010, Guilin, Nov. 8-Nov12 (2010).

[5] M. Zhang, R.Y. Fu, D. Krizan, B.C. De Cooman and L. Li, Continuous Cooling Transformation diagrams and properties of micro-alloyed TRIP-assisted steels, Materials Science & Engineering A. Vol. 438-440 (2006) 296-299.

DOI: 10.1016/j.msea.2006.01.128

[6] W.M. Zeng, M. Zhang, L. Li, and R.Y. Fu, Continuous Cooling Transformation Characteristics of Ultra-high Strength Micro-alloy Complex Phase Steel, Shanghai Metals. Vol. 32 n1 (2010) 19-22.