It is known that with electron beam welding produced in vacuum environment, deep and narrow welds with superior quality can be achieved. In some studies, this has inspired to use vacuum also with laser in order to improve already good performance achieved in atmospheric pressure. It has been reported that the use of vacuum increases penetration, change profile of weld cross-section and produce less porosity.
In this study bead-on-plate Nd:YAG-laser welding experiments were carried out in vacuum and in atmospheric pressure in order to clarify the effect of vacuum on penetration and weld bead geometry. Materials used in the experiments were austenitic stainless steels AISI 304L, AISI 316LN and basic mild steel S235. Evaluations of the welds were done by visually and macroscopically from the macro cross-sections. Also occurrence of weld defects was taken into account.