The influence of thermal cutting on the properties and quality of the cut surfaces toughened steel S 960QL

Abstract

In this paper results of investigation of air plasma, oxygen, laser beam cutting processes on quenching and tempering S 960QL steel surface quality were shown. In most cases a cutting process is the first technological operation from which the manufacturing process begins. In that case changes in the material during this process have a significant effect on the final quality of the manufactured parts. The choice of cutting method depends on the requirements and technical capabilities i.e. type and thickness of material, dimensional tolerances, economic factors, cutting speed or shape of the element. The main goal of this study was to investigate the effect of cutting processes to the surface quality. The obtained cut surfaces have been subjected to ISO 9013:2017 (surface roughness, rectangularity tolerance), as well as cut widths and breakthrough holes diameters have been measured. In the last stage the metallography examination and hardness measurements were accomplished. Hardness measurement of samples after cutting was done by Vickers's method on Wilson Wolpert 401 MVD at load 100g. Macroscopic studies to determine the heat affected zone were performed using a metallographic microscope light stereoscopic Olympus SZX9. Focusing on operating properties of the cut material, attention should be paid to the structural and chemical changes that occur due to the influence of the heat cycle. A heat-treated steel is particularly susceptible to a loss of material properties acquired during heat treating and hardening of the surface layer.