Adaptive Welding of S960QC UHSS for Arctic Structural Applications

Abstract

The construction of welded structures capable of withstanding the harsh operating conditions found in the Arctic region is essential for effective exploitation of the area. This paper examines the usability of S960QC UHSS as potential weldable material for lightweight Arctic structural constructions. The paper concurrently explores the applicability of an adaptive robotic GMAW process in welding the UHSS material. The adaptive welding system featured an infrared thermo-profile scanner. S960QC UHSS was welded in two different fillet joint orientations employing PA and PB welding positions. Using the adaptive welding system, the behavior of welding parameters such as current, voltage and heat input and their effect on the temperature of the weld seam were monitored in relation to the metallurgical properties of the welds. It was observed that the orientation of the joint geometry influences weld penetration and the shape of the weld. Metallurgical tests performed across the weld metal revealed that, using heat inputs between 0.5–0.65 kJ/mm, weld hardness between 375–397 HV5 can be achieved. The hardness values together with impact strength of 33–50 J at an operating temperature of -40 oC demonstrate material properties suitable for Arctic structural applications where excellent strength-to-weight ratio and high load carrying capacity are required. The paper contributes to the field of lightweight steel construction and digitization in welding where adaptive intelligent systems are harnessed in sensing, monitoring, predicting and modelling of the welding process for weld quality control and assurance purposes.