Abstract

In this paper, a comparison of the mechanical properties of high-strength low-alloy S460Nsteel welded joints is presented. The welded joints were made by the gas metal arc welding (GMAW)process in the air environment and water, by the local cavity welding method. Welded joints were testedfollowing the EN ISO 15614-1:2017 standard. After welding, the non-destructive—visual, penetrant,radiographic, and ultrasonic (phased array) tests were performed. In the next step, the destructive tests,as static tensile-, bending-, impact- metallographic (macroscopic and microscopic) tests, and VickersHV10 measurements were made. The influence of weld porosity on the mechanical properties of thetested joints was also assessed. The performed tests showed that the tensile strength of the jointsmanufactured in water (567 MPa) could be similar to the air welded joint (570 MPa). The standarddeviations from the measurements were—47 MPa in water and 33 MPa in the air. However, it was alsostated that in the case of a complex state of stress, for example, bending, torsional and tensile stresses,the welding imperfections (e.g., pores) significantly decrease the properties of the welded joint.In areas characterized by porosity the tensile strength decreased to 503 MPa. Significant differenceswere observed for bending tests. During the bending of the underwater welded joint, a smallerbending angle broke the specimen than was the case during the air welded joint bending. Also,the toughness and hardness of joints obtained in both environments were different. The minimumtoughness for specimens welded in water was 49 J (in the area characterized by high porosity) and inthe air it was 125 J (with a standard deviation of 23 J). The hardness in the heat-affected zone (HAZ)for the underwater joint in the non-tempered area was above 400 HV10 (with a standard deviation of37 HV10) and for the air joint below 300 HV10 (with a standard deviation of 17 HV10). The performedinvestigations showed the behavior of S460N steel, which is characterized by a high value of carbonequivalent (CeIIW) 0.464%, during local cavity welding.

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