Tensile and fatigue properties of laser-welded ultra-high-strength stainless spring steel lap joints

The study was performed to investigate the usability of thin 0.3 mm thick ultra-high-strength stainless spring steel in laser-welded simple panel structures. The mechanical properties of the laser welded joints in lap-shear specimens were investigated. The fatigue and shear strength of laser joints were experimentally investigated using continuous and intermittent lap joints that were welded using various energy inputs. The properties of separate laser welds were characterized by hardness testing and optical microscopy. Results of the hardness measurements showed that there was softened area at heat-affected-zone of the welds. Due to the weld mismatch, significant strain hardening took place at the weld seams. The shear strength of tested continuous lap joints was slightly lower compared to the yield strength of the base material. Fatigue strength of the studied lap joints was at acceptable level for dynamically loaded simple panel structures and the fatigue strength of the weld seams was in practice dependent on the weld area instead of weld type. (C) 2019 The Authors. Published by Elsevier B.V.