Product Code: ICAL09_404

Laser Beam Welding with Hypereutectic ALSI Filler Material
Authors:
Thomas Seefeld, BIAS; Bremen Germany
Frank Buschenhenke, Bias; Bremen Germany
Frank Vollertsen, Bias; Bremen Germany
Presented at ICALEO 2009

For laser welding of AlMgSi (6xxx) alloys filler alloys are commonly required to reduce the hot cracking susceptibility by rising the silicon content in the weld pool to a non critical value. For slender welds obtained e.g. in welding with high brightness lasers, this is often difficult to achieve. The use of hypereutectic Al-Si filler materials might be helpful; however these fillers are not readily available in the form of thin wire. In the present work, hypereutectic Al-Si filler alloys with up to 30% Si and additional grain refiners were produced by spray forming. These were processed into strip material, and the effect on hot cracking susceptibility of the weld metal was demonstrated for thin disc laser welding using the delta-test. Furthermore, filler wire was produced from spray formed AlSi18 material. The 1.2 mm wire was continuously fed during laser welding with a thin disc laser. A strong gradient of the silicon concentration was observed between the top and the root regions of the weld, indicating a lack of vertical transport of alloying elements from the filler within the melt pool. Thus an alternating magnetic field was thus applied to stir the melt, and it was demonstrated that a supercritical silicon concentration and a homogeneous distribution were achieved in all regions of the melt pool.