EFFECT OF HEAT TREATMENT ON THE ABRASIVE WEAR OF WELDED JOINTS OF MARTENSITIC STEEL WITH BORON

Abstract

The welding of martensitic steels in any case results in a reduction of mechanical properties and thus resistance to abrasive wear, both in the zone of the weld material and the broad heat-affected zone. This is due to the maximum strength of commercially available welding consumables not exceeding the tensile strength R_m value of 1000 MPa, which for steels with a claimed hardness of 500 HBW and a strength of min. 1500 MPa, results in a reduction of mechanical properties in the zone of the weld material by a minimum of 40% compared to the base material. To address this issue, the authors decided to subject welded joints of selected high-strength steel to comprehensive heat treatment procedures aimed at restoring the martensitic microstructure in the weld zone. The study demonstrated that the hardness of the weld material could be increased from 213 HBW in the as-welded state to 357 HBW after heat treatment. This improvement led to a corresponding increase in the relative abrasive wear resistance coefficient k_b, rising from 0.87 to 0.97, bringing it closer to that of the base material (k_b = 1.00).