Effect of hot-stamping process conditions on the changes in material strength

Abstract

According to the recent trend of increasing demand in weight reduction of car bodies for the improvement of vehicle safety and gas mileage, there exists a forming method that makes use of the hot-stamping process as a means that satisfies all of the conditions above. However, there is insufficient systematic technical information on the method of heating material and setting up the forming process in case of the hot-stamping technique. A material heating device was manufactured in this study and the temperature profile for the forming process was created in order to design the material heating technique and the forming process in the hot-stamping method. Furthermore, in order to study the changes in strength according to the hot-stamping forming variables, high temperature forming was conducted according to forming variables such as forming speed, rapid cooling time, and material rolling direction. In order to verify the subsequent results, the springback was measured to assess the material hardness and to check the forming precision. In addition, a stamping analysis and quenching analysis were conducted on the experiment conditions through a commercial finite element analysis program, and the results of comparing the hardness distribution with the test values showed similar trends. Based on the results of the analysis, having the shortest possible material transport time would allow for the production of products with evenness and high strength.