Concept Validation for Selective Heating and Press Hardening of Automotive Safety Components with Tailored Properties

Abstract:

A new strategy termed selective heating and press hardening, for hot stamping of boron steel parts with tailored properties is proposed in this paper. Feasibility studies were carried out through a specially designed experimental programme. The main aim was to validate the strategy and demonstrate its potential for structural optimisation. In the work, a lab-scale demonstrator part was designed, and relevant manufacturing and property-assessment processes were defined. A heating technique and selective-heating rigs were designed to enable certain microstructural distributions in blanks to be obtained. A hot stamping tool set was designed for forming and quenching the parts. Demonstrator parts of full martensite phase, full initial phase, and differentially graded microstructures have been formed with high dimensional quality. Hardness testing and three point bending tests were conducted to assess the microstructure distribution and load bearing performance of the as-formed parts, respectively. The feasibility of the concept has been validated by the testing results.

• Periodical: Key Engineering Materials (Volumes 622-623)
• Pages: 1124-1131
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.622-623.1124
• Online since: September 2014
• Authors: Nan Li*, Jian Guo Lin, Trevor A. Dean, Damian Dry, Daniel S. Balint
• Keywords: Boron Steel, Hot Stamping, Press Hardening, Selective Heating, Tailored Properties

References

[1] H. Karbasian. and A.E. Tekkaya, A review on hot stamping, Journal of Materials Processing Technology, 2010. 210(15): pp.2103-2118.

DOI: 10.1016/j.jmatprotec.2010.07.019

[2] N. Li, et al. Investigation on the mechanical properties of as-formed boron steels for optimizing process strategies in hot stamping, the 14th International Conference of Metal Forming, (2012).

[3] D. Thomas and D.T. Detwiler, Microstructural optimization of automotive structures, HONDA MOTOR CO., LTD. (Tokyo, JP), U.S. Patent 20090242086, (2009).

[4] N. Li, et al., Experimental characterisation of the effects of thermal conditions on austenite formation for hot stamping of boron steel, submitted to Philosophical Magazine, (2014).

[5] N. Li, Fundamentals of materials modelling for hot stamping of UHSS panels with graded properties, PhD thesis, Department of Mechanical Engineering, Imperial College London, (2013).

[6] ThyssenKrupp Steel, Hot press hardening manganese-boron steels MBW for ultrahigh strengths, (2008).

[7] A. Naganathan and L. Penter, Sheet metal forming - processes and applications, Hot stamping, ASM International, (2012).

DOI: 10.31399/asm.tb.smfpa.t53500133

[8] J. Cai, Modelling of phase transformation in hot stamping of boron steel, PhD thesis, Department of Mechanical Engineering, Imperial College London, (2011).