摘要
以1.5 GPa级热冲压成形钢的性能为基准,利用单轴拉伸、三点弯曲、缺口拉伸试验从伸长率、强度、极限冷弯角、裂纹形核功等多角度精准评价2 GPa级热冲压成形钢的强韧性,并通过加权计算综合评分的方法表征强韧性.结果表明,1.5 GPa、2 GPa和2GPa+AS热冲压成形钢烘烤后的屈服强度、伸长率、极限冷弯角、裂纹形核功等多种表征材料强韧性的指标均有所提高.与1.5 GPa钢相比,2 GPa与2GPa+AS钢在其抗拉强度范围内具有高的安全性能,但材料一旦产生孔洞或微裂纹,微裂纹将迅速扩展至零件开裂.经加权计算综合评分得出热冲压成形钢的强韧性综合评价结果,其评分高低顺序为2 GPa＞1.5 GPa＞2 GPa+AS.
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.
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万方数据