Impact welding of ultra-high-strength stainless steel in wrought vs. additively manufactured forms

15-5 PH stainless steel (SS) possesses both high strength and good corrosion resistance and is often used in aerospace components. However, age-hardened 15-5 PH SS can lose up to 20% of its strength during fusion welding due to overaging brought on by heat effect. This work addresses the problem of strength reduction observed in 15-5 PH SS by employing the low-heat welding technique of impact welding. Both wrought (W) and additively manufactured (AM) versions of 15–5 PH SS were investigated through experimentation. All workpieces were age-hardened to condition H900 prior to welding. Best weld microstructures and peel strengths were obtained at impact angles of 12°, for both W and AM variants. Peak peel strength for W welds exceeded 178 N/mm, and for AM welds, 141 N/mm. Failure through base material, which was a most desirable failure mode, was obtained for both material types, though further work will be needed to obtain this failure mode repeatably. Thus, the capability of obtaining strong welds with age-hardened 15-5 PH SS was demonstrated. This capability can help eliminate the need for post-weld heat treatment, thus saving significant time and cost and opening up new design possibilities.