Comparison of Drawability between Warm Forming and Cold Forming of Aluminum 6xxx Alloys

Abstract

The automotive industry has significant interests and material applications involving multiple aluminum alloys (5xxx, 6xxx, and 7xxx) for light weighting. However, the industry experiences a rather lengthy development time for utilizing aluminum alloys and the need for standard approaches. This paper compares the drawability of various aluminum 5xxx, 6xxx, and 7xxx alloys among cold forming and warm forming processes. A warm forming (WF) test cell was established to conduct warm forming tests with real-time monitoring and controlling the heating and forming temperatures of aluminum blanks during heating, part transferring and stamping. For cold forming trials, a 300-Ton servo press was used for obtaining the maximum drawability. A cross-form die was used to compare the aluminum drawability between cold and warm forming processes. Increased drawability varied with different aluminum 6xxx alloys. The warm-forming process window was determined for different aluminum alloys. This paper also compares finite element (FE) prediction results of the forming process between advanced material yield function model, Barlat 2000, and a conventional model, Hill 48. The Barlat 2000 model gave a superior correlation to both cold and warm forming experimental results compared with the Hill 48 model.