STRUCTURAL TRANSFORMATIONS OF CARBON AND ALLOY STEELS IN HEAT-AFFECTED ZONE WITH AIR-ARC CUTTING.

The effect of parameters of air-arc cutting on structural changes and the likelihood of carbon pick-up by the surface in the region of cut edges was examined in non-heat-treated steels St3, 40, 40Kh06, and 30Kh2N2M. With an increase in the angle of inclination of the electrode, there is an increase in the depth of the heat-affected zone. Excessive hardening of the cut edges is due to the austenite-martensite transformation and not to carbon pickup by the surface. To avoid the formation of martensite structures at the surface, it is advisable to incline the electrode at not more than 30-40 degree .