Effect of the welding position on weld quality when laser welding Inconel 617 Ni-based superalloy

Abstract

Inconel 617 Ni-based superalloy sheets were joined using a laser-welding process. The welding experiments were conducted on four different welding positions (i.e., flat, horizontal, vertical-up, and vertical-down), using two sets of welding parameters with different heat inputs. Then, the geometry, internal defects, mechanical properties, and molten-pool dynamics of the laser joints were evaluated. The results showed that, when using high-heat input parameters, the welding position has an obvious effect on the laser weld quality. The top surface of the flat weld and the root surface of the vertical-down weld are both slightly concave. Moreover, the horizontal weld and vertical-down weld have serious keyhole-induced porosity defects, which lead to relatively worse mechanical properties. The analysis shows that the stability of keyhole differs for different welding positions; keyhole-induced porosity is easily generated in the horizontal and vertical-down positions. Moreover, solid metal blocks escape routes of the bubbles, resulting in more serious porosity for these welding positions. However, when using low-heat input parameters, the welding position has less influence on the laser weld quality because there is less molten metal, which makes the keyhole more stable in different welding positions.