Development of Strength Distributed Hot Stamp Parts
To be published on April 2, 2019 by SAE International in United States
Structural parts, such as the center pillar, are a multiple structure, consisted by layers of the high-strength panels and the high-toughness panels, to control the deformation mode during a crash. If we are able to make this multi-layered structure into one panel, which has different hardness within it, we will be able to make a lightweight panel. In this study, we have developed the method to fabricate a ‘lightweight center pillar’ with the following processes. First, the whole surface of the panel is hardened by quenching in the hot stamp process. Next, certain areas of the panel are softened by the partial tempering. We have found that the temperature zone for softening is between A1 and A3 transformation temperature, and it is easy to perform a rapid and accurate tempering by utilizing the property of Induction Heating around the Curie temperature between A1 and A3 transformation temperature. As a result, we have established the method to fabricate the ‘lightweight center pillar’ that has a higher collision resistant performance by integrating the high-strength part and the high-toughness part into a single panel.