Laser beam structured sheets - a new potential for sheet metal forming

摘要

The increasing requirements of car body manufacturers concerning formability and load of sheet metal structures necessitate new approaches in forming technology. Especially the requirements as regards local loads and local forming behaviour of the components vary significantly. In the field of welding technology there is a verified effect of emerging higher strengths in the welding seam. Using a laser, similar effects can be applied to change the material properties locally. In the current investigation the use of a laser beam allows for creating very small heat-affected areas of a width from 0.5 mm up to 5 mm. These areas are characterised by a significantly higher hardness and strength. Depending on the sheet metal material, areas of higher and lower hardness can be produced. Using laser heat-affected zones in sheet metal makes it possible to increase the drawing depth without necking or cracks. The heat-affected zones increased the stiffness in the critical necking area and hence moved the critical strains to the surrounding area. The required formability was guaranteed by the adjacent areas and the draw depth can be increased.