Softening of hot formed steel

Hot formed steel is the most successful method in the last few years to reduce weight, save cost and increase safety in the automotive industry. It is still gaining importance for automotive body parts because of its advantageous material properties. Especially its high strength of about 1500MPa makes it possible to manufacture structural parts like B-Pillars.Car manufacturers look into the usage of flaps and cutouts in the design of these parts. Using flaps within the assembly process would be helpful for part-positioning. Cutouts are used to create pull-throughs with smoothed, rounded edges. The high hardness in the press hardened part has to be reduced in those specific areas to fulfill their intended task. Implementing this softening process into the forming and heat treatment is hard. A laser heat treatment process has been developed which is able to reduce hardness in those specific areas of automotive parts. With this process energy is only placed were its needed and hardness can be reduced by more than 50% within seconds with transition zones smaller than 15mm to the non treated material.The softening process can be applied to the parts within the same laser machine system which is used for the cutting process.