从汽车用22MnB5钢三种热冲压成形件(国产A柱、进口B柱和用进口钢板生产的防撞杆)上制取不同宽度的冷弯试样(试样的最小宽度至少为板厚的20倍)和非标拉伸试样, 按照德国标准VDA 238-100进行弯曲试验, 比较了三种热成形件的冷弯性能; 此外还进行了拉伸试验, 并观察了拉伸断口和弯曲断口的形貌。结果表明: 三种热成形件的组织均为板条马氏体, 它们的拉伸性能相当, 拉伸断口均分为三个区, 即纤维区、放射区和剪切唇, 放射区为少见的条带状; 三种热成形件的弯曲角度相近, 均小于60°, 冷弯性能相当, 这与它们的显微组织相同有关; 弯曲断口形貌呈不同形态的韧窝。

The bending samples with various width and non-standard tensile samples were cut from three kinds of 22MnB5 steel hot stamping parts (domestic A pillar, impute B pillar and door beam made from impute steel plate), the width of bending sample should be more than 20 times thickness. Bending test was carried out according to German standard VDA 238-100, and cold bending properties of various hot stamping parts were compared. In addition, tensile test was carried out, and tensile fracture morphology and bending fracture morphology were observed. The results show that the microstructure of three kinds of hot stamping parts all were lath martensite, their tensile properties were about the same. Tensile fracture can divide three domain: fiber area, radical area and shear lip. The radical zone is infrequent strip and band structure. The measured bending angles of three hot stamping parts were about the same and less than 60°, this related to their same microstructure. The morphology of fracture for bending samples was dimple structure with different morphology.