Characterization of the Tribological Behavior of Different Tool Coatings and Dry Lubricant for High‐Strength Aluminum Alloys at Elevated Temperatures

The use of high‐strength aluminum components in automotive manufacturing offers the opportunity to reduce vehicle weight significantly and provide new lightweight potentials. In the past, the so‐called hot forming and quench process (HFQ) successfully demonstrates the potential for the production of complex‐shaped components made out of age‐hardenable high‐strength aluminum alloys. Currently, no method permits wear‐free quench forming without the use of lubricants. To fulfill the increasing ecological and economic requirements, it is necessary to identify wear‐reducing techniques to promote this forming technology in the future. This contribution investigates the interaction of lubricant and tool coatings on the tribological performance during quench forming of the high‐strength aluminum alloy AA7075 at elevated temperatures. For this purpose, the tribological behavior is investigated using both, flat strip drawing tests and deep drawing operations. Subsequently, the component quality is compared and discussed. The results demonstrate that tool coatings are effective for the production of high‐strength components in the HFQ process with minimal or even no lubrication and thus provide ecological as well as economic advantages. High friction and wear limit the thermal‐assisted forming of high‐strength aluminum alloys. Tool coatings and lubricants enable failure‐free forming at elevated temperatures. Diamond‐like carbon (DLC) tool coatings exhibit beneficial tribological properties. Strip drawing tests as well as forming experiments illustrate that deep drawing operations under dry conditions are possible at elevated temperatures.