Laser brazing of high strength steels

Abstract

The application of high strength steels demands for joining methods for these steels. As welding may be difficult for some of the steels due to a detrimental effect of weld metal and the heat affected zone on the mechanical properties of the joint, brazing of these steels might be a better solution.Therefore, laser brazing of high-strength steels is regarded. Besides the brazeability of high strength steels such as TRIP800, the possibility of brazing these steels to low alloyed steels (DC05) with or without zinc coatings is discussed.The heat affected zones (HAZ) of the joints were analysed and the change of hardness in the HAZ was measured. It was established that the hardness of the steels is increased within the HAZ for all steels considered. Even an intermetallic phase seam was detected in the steel-filler metal interface. These results are correlated with the strength of the joint and cracking behaviour. This behaviour was experimentally verified by static fracture tests. So the influence of the intermetallic phases and the HAZ on the strength of the joint is better understandable. The results will contribute to an improved understanding of the brazeability of high strength steels.The application of high strength steels demands for joining methods for these steels. As welding may be difficult for some of the steels due to a detrimental effect of weld metal and the heat affected zone on the mechanical properties of the joint, brazing of these steels might be a better solution.Therefore, laser brazing of high-strength steels is regarded. Besides the brazeability of high strength steels such as TRIP800, the possibility of brazing these steels to low alloyed steels (DC05) with or without zinc coatings is discussed.The heat affected zones (HAZ) of the joints were analysed and the change of hardness in the HAZ was measured. It was established that the hardness of the steels is increased within the HAZ for all steels considered. Even an intermetallic phase seam was detected in the steel-filler metal interface. These results are correlated with the strength of the joint and cracking behaviour. This behaviour was experimentally verified by static fracture tests. So the influence of the inte...