Evaluation of the mechanical properties of butt-welded joints of structural steel performed by a robot using the MAG process

Abstract

The aim of this paper is to present the results of mechanical testing of the carbon structural steel S235JR and its butt-welded joints, which were performed using a robot (MAG process). One pair of plates with dimensions 200x500 mm and a thickness of 12 mm was prepared for welding. The preparation involved laser cutting and groove preparation for welding. A V-groove was machined on a CNC milling machine, in accordance with the thickness of the base material. Additionally, a special copper backing strip was prepared for welding. The filler material selected was electrode wire with a diameter of 1.2 mm, designated G42 4 C/M 3Si1 according to EN ISO 14341-A. Welding parameters were selected for both the root weld and the filler welds based on the chosen filler material. After welding, non-destructive testing (NDT) was conducted, including visual inspection, penetrant testing, and ultrasonic testing. The tests confirmed that the welding was successfully performed. Upon completion of welding, samples were prepared from the base material and its welded joints and tensile and impact toughness tests were conducted. The obtained results were analyzed, and the paper also provides an assessment of the suitability of robotic welding for this type of base material and the prepared joint geometry (in terms of mechanical properties and weld quality). In addition to the experimental results, the paper presents detailed descriptions of the procedures for preparing parts for welding, testing samples, as well as the testing itself, both destructive and non- destructive.