Tribological conditions are challenging when forming high strength aluminum alloys at elevated temperatures due to the sticking behavior of aluminum and potential material transfer to the die in the form of die pick-up. The current study examines the elevated temperature performance of several lubricants as well as a Physical Vapor Deposition (PVD) die coating, in conjunction with a 7000-series aluminum alloy sheet under conditions corresponding to warm forming of automotive structural components. Lubricant performance is characterized from the coupon-to-component level at temperatures in the range of 25–230°C. The classical coupon-level Twist Compression Test (TCT) is modified to perform elevated temperature experiments and used to rank the lubricants in terms of their steady-state coefficient of friction and resistance to lubricant breakdown as a function of temperature. It is found that both the friction coefficient and lubricant breakdown distance need to be considered for lubricant assessment. The studied PVD die coating is found to successfully mitigate lubricant breakdown for the FORGE EASE AL 278 at 230°C in the TCT. In parallel, warm forming experiments considering deep drawn cylindrical cups and U-channel rail sections (representative of a structural side member) are used to evaluate lubricant performance under real stamping conditions. The trends in forming performance (draw-in length, final blank perimeter, visual scoring, and forming force) confirm the lubricant ranking obtained from the TCT coupon tests, with the Teflon® PTFE film as the most effective followed by the FORGE EASE AL 278, OKS 536, and the LPS® Dry Film PTFE Spray Lubricant. For the highest test temperature, the LPS® Dry Film PTFE Spray Lubricant exhibits breakdown in the TCT at short sliding distances and results in fracture during deep drawing.

在高温下形成高强度铝合金时，由于铝的粘着行为以及潜在的材料以芯片拾取的形式转移到模具中，因此摩擦条件具有挑战性。当前的研究是在与汽车结构部件的热成型相对应的条件下，结合7000系列铝合金板，研究了几种润滑剂以及物理气相沉积（PVD）模具涂层的高温性能。润滑性能的特征在于在25–230°C的温度范围内，试样到部件的水平。经典的试样级扭曲压缩试验（TCT）进行了改进，以进行高温实验，并用于根据润滑剂的稳态摩擦系数和抗润滑剂击穿强度随温度变化对润滑剂进行排名。已经发现，摩擦系数和润滑剂击穿距离都需要同时进行润滑剂评估。发现在230°C的TCT中，对于FORGE EASE AL 278，研究的PVD模具涂层可成功减轻润滑剂的分解。同时，采用考虑了深冲圆柱杯和U形钢轨截面（代表结构性纵梁）的热成型实验来评估实际冲压条件下的润滑剂性能。成型性能的趋势（拉入长度，最终毛坯周长，视觉评分，成型力）确定从TCT试样试验中获得的润滑剂等级，其中Teflon®PTFE膜是最有效的，其次是FORGE EASE AL 278，OKS 536和LPS®干膜PTFE喷涂润滑剂。对于最高测试温度，LPS®干膜PTFE喷涂润滑剂在短滑动距离下的TCT中会出现破裂，并在深冲时导致断裂。