崔振楠, 林利, 朱国明, 康永林, 刘仁东, 田鹏. DP590/DP780高强钢管液压成形的性能[J]. 工程科学学报, 2020, 42(2): 233-241. DOI: 10.13374/j.issn2095-9389.2019.01.15.004
引用本文: 崔振楠, 林利, 朱国明, 康永林, 刘仁东, 田鹏. DP590/DP780高强钢管液压成形的性能[J]. 工程科学学报, 2020, 42(2): 233-241. DOI: 10.13374/j.issn2095-9389.2019.01.15.004
CUI Zhen-nan, LIN Li, ZHU Guo-ming, KANG Yong-lin, LIU Ren-dong, TIAN Peng. Hydroforming performance of DP590/DP780 high-strength steel tube[J]. Chinese Journal of Engineering, 2020, 42(2): 233-241. DOI: 10.13374/j.issn2095-9389.2019.01.15.004
Citation: CUI Zhen-nan, LIN Li, ZHU Guo-ming, KANG Yong-lin, LIU Ren-dong, TIAN Peng. Hydroforming performance of DP590/DP780 high-strength steel tube[J]. Chinese Journal of Engineering, 2020, 42(2): 233-241. DOI: 10.13374/j.issn2095-9389.2019.01.15.004

DP590/DP780高强钢管液压成形的性能

Hydroforming performance of DP590/DP780 high-strength steel tube

  • 摘要: 为对生产进行指导,研究了DP590/DP780高强钢焊管在液压成形过程中的变形行为;使用场发射扫描电镜观察管材周向的横截面以确定基体的组织,通过VMHT30M显微硬度计确定管材的焊缝及热影响区的大小,以便研究液压成形破裂行为;采用液压成形试验机对两种管件进行液压成形研究。实验结果表明:管材在胀形过程中的破裂压力比理论计算公式得到的破裂压力大,破裂位置全部位于靠近焊缝及热影响区的母材区域;随着管径的增大和长径比的增大,管材的极限膨胀率呈现下降趋势;在自由胀形过程中,管材的焊缝区域基本上不发生减薄,最小壁厚位于管材的热影响区和基体的过渡区域,并且壁厚的减薄率在胀形最高点所在截面最大,越靠近管材夹持区,壁厚的减薄率越小。最终得到以下结论:管材液压成形实验是准确获得管材力学性能参数的途径;提高焊接质量有助于控制失效破裂位置;合理选择管材的长径比有利于管材性能的充分发挥;通过合理控制各处的减薄有利于降低液压成形件的破裂风险。

     

    Abstract: In recent years, the automotive industry has become increasingly demanding for the strength of hollow structural parts. To meet the strength and toughness requirements, major automakers have begun to use high-strength steel for the production of automotive hollow structural parts, and the hydroforming process is the most economical way to achieve this purpose. However, studies on the hydroforming process of high-strength steel in the industry are few. To guide the production of high-strength steel hydroformed parts, the deformation behavior of DP590/DP780 high-strength steel welded tube during hydroforming was investigated in this study. The cross section of the circumferential direction of the tube was observed by scanning electron microscopy to determine the microstructure of the base metal. The sizes of the weld and the heat-affected zone of the tube were determined by VMHT30M microhardness tester to study the hydroforming fracture behavior. The deformation behavior of DP590/DP780 high-strength steel welded tube during hydroforming was studied by a tube hydroforming test machine. The experimental results are as follows: the fracture pressure of the tube during the bulging process is larger than the fracture pressure obtained by the theoretical calculation formula, and the rupture position is located in the base metal area near the weld and heat-affected zone. With the increase of the tube diameter and the length-to-diameter ratio, the maximum expansion ratio of the tube exhibits a downward trend. In the process of free bulging, the weld area of the tube is basically not thinned. The position of the minimum thickness is located in the heat-affected zone of the tube and the transition zone of the base body; the wall thickness reduction rate is the largest at the highest point of the bulging region, and the closer to the tube clamping zone, the smaller the wall thickness reduction rate. Finally, the following conclusions can be drawn: the hydroforming experiment of the tube can accurately obtain the mechanical properties of the tube. Improving the welding quality could help to control the failure rupture position. A reasonable selection of the length-to-diameter ratio of the tube is beneficial to the tube overall performance. It is beneficial to reduce the risk of cracking of the hydroformed part by reasonably controlling the thickness reduction rate of each part.

     

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