The paper presents the results of tests of a welded joint of Hardox 450 steel, belonging to the group of weldable high-strength boron steels with increased resistance to abrasive wear. As a result of the conducted research, apart from the basic structural indicators, an attempt was made to determine the correlation between the grain size of the prior austenite in the characteristic weld zones and its basic mechanical properties, such as yield point, tensile strength, percentage elongation after fracture, reduction of area, and impact strength. The scope of research quoted above was carried out for a welded joint of the considered steel at delivery state (directly after welding), in the normalising annealed state, as well as in water-quenched state, using different austenitisation temperatures in the range of 900-1200 °C. The results obtained showed a large influence of the parameters of the applied thermal heat treatment on the selected structural and mechanical properties of the welded joint.
Keywords: Hardox 450 steel; mechanical properties; prior austenite grain size; structures; submerged arc welding (SAW); wear-resistant martensitic steel.