7075铝合金和QRO90模具钢在热成形工况下的摩擦磨损行为

Friction and Wear Behavior of 7075 Aluminum Alloy and QRO90 Tool Steel During Hot Stamping

铝合金在热成形制造过程中存在严重的模具磨损,不但缩短模具使用寿命,还造成工件表面拉毛和成形偏差。为模拟模具钢与7系铝合金在热成形工况下的摩擦过程,搭建单向高温摩擦磨损试验平台,对热成形工况下的摩擦磨损行为展开研究,并通过光学轮廓仪和扫描电镜分析模具钢与铝合金磨损表面形貌。结果发现,热成形过程中黏结磨损和磨粒磨损同时存在,磨损颗粒在粗糙表面上被压实和堆积,对后续的摩擦磨损行为有显著影响。对单向高温摩擦试验的接触副局部进行有限元建模,分析粗糙接触表面上的局部接触条件,探讨其对后续摩擦学行为的作用。分析表明,摩擦过程中存在黏滑现象,局部接触压力受表面形貌影响,显著大于名义载荷,最大等效应力出现在表面之下。这对进一步分析磨损行为、提出合适的表面工程方案提供了基础。

There is serious die wear in the process of hot forming of aluminum alloy,which not only shortens the service life of the die,but also causes the drawing and forming deviation of the workpiece surface.In order to simulate the friction process between die steel and 7 series aluminum alloy under hot forming conditions,a unidirectional high temperature friction and wear test platform was established to study the friction and wear behavior under hot forming conditions,and the wear surface morphology of die steel and aluminum alloy was analyzed by optical profilometer and scanning electron microscope.The results show that adhesive wear and abrasive wear exist simultaneously in the process of hot forming.The abrasive particles are compacted and accumulated on the rough surface,which has a significant influence on the subsequent friction and wear behavior.The local contact condition on rough contact surface was analyzed by finite element modeling for the contact pair of unidirectional high temperature friction test,and the effect of the local contact condition on the subsequent tribological behavior was discussed.The analysis shows that there is a slip-on phenomenon in the friction process,the local contact pressure is significantly greater than the nominal load due to the influence of surface topography,and the maximum equivalent stress appears under the surface.This research provides an important basis for further analysis of wear behavior and the proposal of appropriate surface engineering scheme.