Technological Features of Welding and Heat Treatment of Housing Products Made of Thermomechanically Hardened Steel in Industrial Conditions

High-strength steels are increasingly used to manufacture welded structures in various industries, significantly improving the performance characteristics of products. These strength properties can be achieved through specialized alloying systems, thermomechanical processing, and other methods. The higher the strength and the more complex the strengthening system, the less its technological weldability. Currently, high-strength thermomechanically strengthened steel is increasingly used for the manufacture of welded structures. It offers the required armor resistance at relatively thin sheet thicknesses, but at the same time, it is highly susceptible to cracking in the near-weld zone. Cracks form immediately after welding, as well as over time during operation and external loads. The main cause of their formation is high level of internal stress and hardness values near the fusion line in the base metal, caused by the influence of the thermal cycle of welding. This article, based on the results of experimental studies and mechanical tests of welded joints made of high-strength armor-resistant steel 37У, proposes a heat treatment option to reduce the hardness in the heat-affected zone near the fusion line, which significantly reduces the likelihood of crack formation. The essence of the proposed solution consists of heating the heat-affected zone of a welded joint made by consumable electrode arc welding (MIG) in a protective gas environment of 98 % Ar + 2 % O2 using an austenitic welding wire Св-08Х20Н10Г7Т, through the deposited weld metal using non-consumable tungsten electrode (TIG) welding technology. Local heating of the weld beads is carried out until a liquid pool mirror appears, and all welded joints are processed by rectilinear movement along the axis of the weld. The features of hardness distribution in the heat-affected zone of welded joints made of high-strength steels and the nature of the effect of local heating on them are studied.

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