Thermal cutting of thermomechanically rolled S700MC and heat-treated S690QL steels

Abstract

The article describes the impact of oxygen, HD air plasma and laser beam cutting processes on structural changes and quality of the surface of thermomechanically treated S700MC and heat-treated S690QL steels. Taking into account good quality of obtained cut surface, particular attention shall be attached to the structural and chemical changes due to the impact of the heat cycle. Those modern steels are especially susceptible to a loss of their properties during the heat interaction in thermal cutting processes. The quality of the surfaces after thermal cutting processes were evaluated in accordance to ISO 9013:2017 (bevel angle, surface roughness, rectangularity tolerance). Also, measurements of cut widths and breakthrough holes diameters were accomplished. In the next stage the hardness measurements and metallography examination were performed. The following devices were used for this purpose: metallographic light stereoscopic microscope Olympus SZX9 and Wilson Wolpert 401 MVD for Vickers's hardness measurements.