Influence of Selective Laser Heat Treatment Pattern Position on Geometrical Variation

Selective laser heat treatment allows local modification of material properties and can have wide range of applications within the automotive industry. Enhanced formability and strength are possible to achieve. As the process involves selective heating, positioning of the heat treatment pattern in local areas is vital. Pattern positioning is often suggested based on the part design and forming aspects of the material to avoid failures during manufacturing. Along with improving material properties in desired local areas, the process also produces unwanted distortion in the material. Such effects on variation should be considered and minimized. In this paper, heat treatment pattern is offset from its original position and its effect on geometrical variation is investigated. Boron steel blanks are selectively laser heat treated with a specific heat treatment pattern and then stamped to desired shape. Two heat treatment pattern dimensions are examined. Variation at blank level and after stamping, and springback after stamping is observed. Results show that pattern offsetting leads to higher geometrical variation. Therefore, correct positioning of heat treatment pattern is important to minimize its effect on geometrical variation along with enhancing the material properties. Knowledge from this study will contribute to various stages of the geometrical assurance process.