ABSTRACT
During welding two characteristic areas are formed - hardening and tempering. The depth of these areas reaches 2.5 mm and 8 mm, respectively. Depending on the steel grade, the depth and value of hardness of these areas change. The transition from the first to the second occurs in the area of incomplete recrystallization, which in structure is a mixture of martensite, ferrite and carbides. The total width of the de-hardened area of the heat-affected zone (HAZ), consisting of areas of incomplete recrystallization and tempering, for welded joints with a thickness of 6 - 20 mm and depends on the linear energy of welding and can vary in the range of 3 … 8 mm. The work provides for the first time structured information on the features of the thermal welding cycle and its influence on the mechanical properties in the HAZ metal in the area heated to temperatures from 250 to 1200°C.
