模具摩擦及润滑条件对超高强钢板热冲压成形的影响

Influence of friction and lubrication conditions in the die on hot stamping for ultra high strength steel sheet

以汽车纵梁为研究对象,通过有限元模拟,分析摩擦系数对超高强钢板热冲压成形的影响。在不同润滑条件下,通过热冲压实验,研究润滑条件对超高强钢板热冲压成形的影响。结果表明：随着摩擦系数的增大,热冲压件的厚度变薄,等效应变值增大;无润滑剂的热冲压件存在划痕,出现破裂,氧化严重;石墨润滑的热冲压件存在划痕,出现破裂;玻璃润滑的热冲压件成形质量较好,3种润滑条件下的热冲压件的厚度逐渐增大。玻璃润滑剂有利于改善模具摩擦条件,增强热冲压过程中的抗氧化性。润滑条件对热冲压件金相组织、力学性能影响不大,零件的抗拉强度均达到1460 MPa,显微硬度达到460 HV以上。

For the auto girder,the influence of friction coefficient on the hot stamping for ultra high strength steel steel was analyzed by FEM simulation,and the influence of different lubrication conditions on the hot stamping for ultra high strength steel sheet was conducted by the hot stamping experiments. The results show that with the increasing of friction coefficient,the thickness of hot stamping parts becomes thinner,and the effective strain value becomes bigger. The hot stamping parts without lubricant have scratches,cracks and serious oxidation,and the hot stamping parts with graphite lubricant have scratches and cracks. However,the forming quality of hot stamping parts with glass lubricant is better,and the thickness of hot stamping parts increases gradually under three kinds of lubricant conditions.Thus,the glass lubricant is beneficial to the improvement of friction condition and oxidation resistance in the hot stamping process. Furthermore,the lubricant condition has little influence on the microstructure and mechanical properties of hot stamping parts,and the tensile strength of hot stamping parts is up to 1460 MPa and the microhardness is above 460 HV.