Comprehensive evaluation of strength and toughness of hot stamping steel

doi:10.13251/j.issn.0254-6051.2024.10.046

Abstract

Abstract: Taking the properties of 1.5 GPa grade hot stamping steel as the benchmark, the strength and toughness of 2 GPa grade hot stamping steel were accurately evaluated from multiple perspectives as elongation, strength, ultimate cold bending angle and crack nucleation work by means of uniaxial tensile test, three-point bending test and notch tensile test, and the strength and toughness were characterized by the method of weighted calculation of comprehensive score. The results show that after baking, the yield strength, elongation, ultimate cold bending angle, crack nucleation work which characterize the fracture toughness of the 1.5 GPa, 2 GPa and 2 GPa+AS hot stamping steel specimens are improved. Compared with the 1.5 GPa steel, the 2 GPa and 2 GPa+AS steels have higher safety performance within their tensile strength range, however, once holes or microcracks are formed in the specimen, the microcracks will rapidly expand to crack. Through weighted calculation of the comprehensive score, it is concluded that the comprehensive evaluation results of the strength and toughness of the tested hot stamping steels from high to low are 2 GPa>1.5 GPa>2 GPa+AS.

Key words: hot stamping steel, strength and toughness, multiple perspective characterization

CLC Number:

TG142.1

Wang Qiuyu, Xu Kuan, Li Liming, Liu Shuying, Zhang Saijuan. Comprehensive evaluation of strength and toughness of hot stamping steel[J]. Heat Treatment of Metals, 2024, 49(10): 284-289.

References

[1]胡平, 戴明华, 盈亮, 等. 热成形高强度钢22MnB5在车身轻量化设计中的应用[C]//中国汽车轻量化技术研讨会. 2012: 281-237.
Hu Ping, Dai Minghua, Ying Liang, et al. Application of hot formed high strength steel 22MnB5 in lightweight design of vehicle bodies[C]//China Automotive Lightweight Technology Seminar. 2012: 281-237.
[2]康永林. 现代汽车板工艺及成形理论与技术[M]. 北京: 冶金工业出版社, 2009: 46-52.
Kang Yonglin. Theory and Technology of Processing and Forming for Advanced Automotive Steel Sheets [M]. Beijing: Metallurgical Industry Press, 2009: 46-52.
[3]Tang B, Yuan Z, Cheng G, et al. Experimental verification of tailor-welded joining partners for hot stamping and analytical modeling of TWBs rheological constitutive in austenitic state[J]. Materials Science and Engineering A, 2013, 585: 304-318.
[4]马宁, 申国哲, 张宗华, 等. 高强度钢板热冲压材料性能研究及在车身设计中的应用[J]. 机械工程学报, 2011, 47(8): 60-63.
Ma N, Shen G Z, Zhang Z H, et al. Material performance of hot-forming high strength steel and its application in vehicle body[J]. Journal of Mechanical Engineering, 2011, 47(8): 60-63.
[5]Chang Z Y, Li Y J, Wu D. Enhanced ductility and toughness in 2000 MPa grade press hardening steels[J]. Materials Science and Engineering A, 2020, 784(139): 329-342.
[6]Guo R Q, Ying L, Hu P. Experimental study on hot bending of 22MnB5 steel[J]. Advanced Materials Research, 2011, 314-316: 66-69.
[7]Zhang S Q, Huang Y H, Sun B T, et al. Effect of Nb on hydrogen induced delayed fracture in high strength hot stamping steels[J]. Materials Science and Engineering A, 2015, 626(36): 136-138.
[8]Liu H P, Lu X W, Jin X J, et al. Enhanced mechanical properties of a hot stamped advanced high-strength steel treated by quenching and partitioning process[J]. Scripta Materialia, 2011, 64: 749-758.
[9]Mohrbacher H. Martensitic automotive steel sheet-Fundamentals and metallurgical optimization strategies[J]. Advanced Materials Research, 2015, 1063(12): 130-145.
[10]王华, 史文, 何燕霖, 等. Mn和P在超低碳烘烤硬化钢中的分布形态及其对拉伸行为的影响研究[J]. 金属学报, 2011, 47(3): 263-268.
Wang H, Shen W, He Y L, et al. Study of Mn and P solute distributions and their effect on the tensile behavior in ultra low carbon bake hardening steels[J]. Acta Metallurgica Sinica, 2011, 47(3): 263-268.
[11]Kolleck R, Veit R, Merklein M, et al. Investigation on induction heating for hot stamping of boron alloyed steels[J]. CIRP Annals, 2009, 58(1): 275-278.
[12]ASTM E8-2021. Standard test methods for tension testing of metallic materials[S].
[13]VDA 238-100. Plate bending test for metallic semi-finished materials[S].
[14]Liang Y, Lu J D, Chang Y, et al. Optimization evaluation test of strength and toughness parameters for hot-stamping high strength steels[J]. Journal of Iron and Steel Research International, 2013, 20(11): 51-56.
[15]江海涛, 康永林, 于浩, 等. 烘烤硬化汽车钢板的开发与研究进展[J]. 汽车工艺与材料, 2005(3): 1-4, 7.
Jiang Haitao, Kang Yonglin, Yu Hao, et al. Research progress and development of bake hardening steel sheet for automobile[J]. Automotive Technology and Materials, 2005(3): 1-4, 7.
[16]Chang Y, Wang C Y, Zhao K M, et al. An introduction to medium Mn steel: Metallurgy, mechanical properties and warm stamping process[J]. Materials and Design, 2016, 94: 424-434.
[17]Zhong Y, Xiao F R, Zhang J W, et al. In situ TEM study of the effect of M/A films at grain boundaries on crack propagation in an ultra-fine acicular ferrite pipeline steel[J]. Acta Materialia, 2006, 54(2): 435-443.
[18]Arola A M, Kaijalainen A, Kesti V, et al. Digital image correlation and optical strain measuring in bendability assessment of ultra-high strength structural steels[J]. Procedia Manufacturing, 2019, 29(4): 398-413.
[19]Li N, Lin J, Balint D S, et al. Modelling of austenite formation during heating in boron steel hot stamping processes[J]. Journal of Materials Processing Technology, 2016, 237(12): 394-402.