预变形状态对双相钢成形极限能力影响分析

Analysis of Influence of Pre-deformation State on Forming Limit Ability of Dual-phase Steel

为了更好地模拟双相钢在冲压过程中的实际成形状态,选择不同厚度的DP780试样,通过拉伸试验进行不同程度的预变形,然后进行扩孔试验。研究了不同厚度DP780横纵向预变形对双相钢成形极限能力的影响。得到结论:预变形量大小与方向都会影响双相钢成形极限能力;双相钢在冲压变形过程中扩孔率会发生减小,并且在小变形量下扩孔率减小幅度较大,所以在工业生产中选材时需要考虑留出更多的安全裕度,来保证材料成形顺利,避免开裂等问题发生;相同冲压条件下,应该尽量控制材料厚度偏高以抵抗冲压开裂情况;纵向预变形下材料成形极限能力减小幅度较小,所以当材料成形过程不顺利及发生开裂等问题时,可以尝试旋转料片方向,使材料旋转90°后进行冲压。

In order to better simulate the actual forming state of dual-phase steel in the stamping process, DP780 samples with differen t thicknesses are selected, pre-deformed to different degrees through tensile tests, and then reaming tests are carried out. The influence of different thickness DP780 transverse and longitudinal pre-deformation on forming limit capacity of dual-phase steel was studied. The conclusions are as follows: the magnitude and direction of pre-deformation will affect the forming limit capacity of dual-phase steel;The reaming rate of dual-phase steel decreases during stamping deformation, and the reaming rate decreases greatly under small deformation. Therefore, more safety margin should be considered when selecting materials in industrial production to ensure smooth material forming and avoid cracking and other problems;Under the same stamping conditions, the thickness of the material should be controlled as high as possible to resist stamping cracking;The reduction of material forming limit capacity under longitudinal pre-deformation is small, so when the material forming process is not smooth and cracking occurs, try rotating the direction of the material sheet to make the material rotate 90 degrees before punching.