Effect of hot stamping parameters on the mechanical properties and microstructure of cold-rolled 22MnB5 steel strips

Abstract

Thermomechanical experiments were carried out to reproduce the hot stamping process and to investigate the effects of process parameters on the microstructure and mechanical properties of stamped parts. The process parameters, such as austenitizing temperature, soaking time, initial deformation temperature and cooling rate, are studied. The resulting microstructures of specimens were observed and analyzed. To evaluate the mechanical properties of specimens, tensile and hardness tests were also performed at room temperature. The optimum parameters to achieve the highest tensile strength and the desired microstructure were acquired by comparing and analyzing the results. It is indicated that hot deformation changes the transformation characteristics of 22MnB5 steel. Austenite deformation promotes the austenite-to-ferrite transformation and elevates the critical cooling rate to induce a fully martensitic transformation.

Keywords

boron steel / strip metal / stamping / mechanical properties / microstructure / phase transitions

References

[1] Åkerström P. Modelling and Simulation of Hot Stamping, 2006, Luleå, Luleå University of Technology, 1

[2] Xing ZW, Bao J, Yang YY. Numerical simulation of hot stamping of quenchable boron steel. Mater. Sci. Eng. A, 2009, 499(1–2): 28.

[3] Karbasian H, Tekkaya AE. A review on hot stamping. J. Mater. Process. Technol., 2010, 210(15): 2103.

[4] Merklein M, Lechler J, Geiger M. Characterisation of the flow properties of the quenchenable ultra high strength steel 22MnB5. CIRP Ann. Manuf. Technol., 2006, 55(1): 229.

[5] Bariani PF, Bruschi S, Ghiotti A, Turetta A. Testing formability in the hot stamping of HSS. CIRP Ann. Manuf. Technol., 2008, 57(1): 265.

[6] Min JY, Lin JP, Li JY, Bao WH. Investigation on hot forming limits of high strength steel 22MnB5. Comput. Mater. Sci., 2010, 49(2): 326.

[7] Li HZ, Wu X, Li GY. Prediction of forming limit diagrams for 22MnB5 in hot stamping process. J. Mater. Eng. Perform., 2013, 22(8): 2131

[8] Tondini F, Bosetti P, Bruschi S. Heat transfer in hot stamping of high-strength steel sheets. Proc. Inst. Mech. Eng. B, 2011, 225(10): 1813.

[9] Abdulhay B, Bourouga B, Dessain C. Experimental and theoretical study of thermal aspects of the hot stamping process. Appl. Therm. Eng., 2011, 31(5): 674.

[10] Boher C, Le Roux S, Penazzi L, Dessain C. Experimental investigation of the tribological behavior and wear mechanisms of tool steel grades in hot stamping of a high-strength boron steel. Wear, 2012, 294–295, 286.

[11] Azushima A, Uda K, Yanagida A. Friction behavior of aluminum-coated 22MnB5 in hot stamping under dry and lubricated conditions. J. Mater. Process. Technol., 2012, 212(5): 1014.

[12] Güler H, Ertan R, Özcan R. Influence of heat treatment parameters on the microstructure and mechanical properties of boron-alloyed steels. Mater. Test., 2012, 54(9): 619.

[13] Naderi M, Ketabchi M, Abbasi M, Bleak W. Semi-hot stamping as an improved process of hot stamping. J. Mater. Sci. Technol., 2011, 27(4): 369.

[14] Naderi M, Ketabchi M, Abbasi M, Bleck W. Analysis of microstructure and mechanical properties of different high strength carbon steels after hot stamping. J. Mater. Process. Technol., 2011, 211(6): 1117.

[15] Mori K, Maeno T, Mongkolkaji K. Tailored die quenching of steel parts having strength distribution using bypass resistance heating in hot stamping. J. Mater. Process. Technol., 2013, 213(3): 508.

[16] Yi HL, Ghosh S, Bhadeshia HKDH. Dual-phase hot-press forming alloy. Mater. Sci. Eng. A, 2010, 527(18–19): 4870.

[17] Zhao YG, Ma BD, Guo HC, Ma J, Yang Q, Song JS. Electropulsing strengthened 2GPa boron steel with good ductility. Mater. Des., 2013, 43, 195.

[18] Shapiro A. Finite element modeling of hot stamping. Steel Res. Int., 2009, 80(9): 658

[19] Cui JJ, Lei CX, Xing ZW, Li CF, Ma SM. Predictions of the mechanical properties and microstructure evolution of high strength steel in hot stamping. J. Mater. Eng. Perform., 2012, 21(11): 2244.

[20] Fan DW, Kim HS, De Cooman BC. A review of the physical metallurgy related to the hot press forming of advanced high strength steel. Steel Res. Int., 2009, 80(3): 241

[21] Movahed P, Kolahgar S, Marashi SPH, Pouranvari M, Parvin N. The effect of intercritical heat treatment temperature on the tensile properties and work hardening behavior of ferrite-martensite dual phase steel sheets. Mater. Sci. Eng. A, 2009, 518(1–2): 1.

[22] Xu PG, Tomota Y, Lukáš P, Muránsky O, Adachi Y. Austenite-to-ferrite transformation in low alloy steels during thermomechanically controlled process studied by in situ neutron diffraction. Mater. Sci. Eng. A, 2006, 435–436, 46.

[23] Nikravesh M, Naderi M, Akbari GH. Influence of hot plastic deformation and cooling rate on martensite and bainite start temperatures in 22MnB5 steel. Mater. Sci. Eng. A, 2012, 540, 24.

[24] Shi ZM, Liu K, Wang MQ, Shi J, Dong H, Pu J, Chi B, Zhang YS, Jian L. Effect of non-isothermal deformation of austenite on phase transformation and microstructure of 22SiMn2TiB steel. Mater. Sci. Eng. A, 2012, 535, 290.

[25] Naderi M. Hot Stamping of Ultra High Stength Steels, 2007, Aachen, RWTH Aachen University, 91

[26] Morito S, Yoshida H, Maki T, Huang X. Effect of block size on the strength of lath martensite in low carbon steels. Mater. Sci. Eng. A, 2006, 438–440, 237.

[27] Xiao FR, Liao B, Qiao GY, Guan SZ. Effect of hot deformation on phase transformation kinetics of 86CrMoV7 steel. Mater. Charact., 2006, 57(4–5): 306.

[28] Porter DA, Easterling KE. Phase Transformations in Metals and Alloys, 1992 2nd Ed. London, Chapman & Hall, 409.