Influence of classified pore contents on the quasi-static and cyclic strength properties of the welded joint in gas-shielded metal arc welding of galvanized, high-strength steels

Abstract

High-strength steel sheets are used in the automotive industry to save weight. In particularly, in the chassis area, high-strength steels are constantly replacing the previously used strength classes of 440–590 MPa. In body in white construction, galvanized sheet steel has had long been established use due to its anti-corrosive effect. In chassis production, steel materials are usually processed without galvanizing. In the automotive industry, demand for galvanized steel sheets for chassis production is increasing. Gas-shielded metal arc welding is an established joining process for chassis components. The zinc layer poses difficulties as it evaporates during the welding process and leads to pores in the resulting weld seam. A pore-filled weld seam can reduce the strength of the welded joint. When designing chassis parts, the influence of the pores in the weld seam on the strength properties is an important finding. It has been shown that the resulting pore content of the weld seam can be influenced by the heat input and the welding process used. The following article presents the findings of a low-energy Cold Metal Transfer (CMT) process and a high-energy pulse process on a hot-dip galvanized high-strength steel of strength class 760 MPa in a sheet thickness of 2.5 mm at the lap joint without a gap.