A comparative study of the thermal and mechanical cutting influence on the cut-edge hardness of structural steels S355 and S1100

Abstract

Thermal and mechanical cutting processes are commonly applied in manufacturing industries for making a specific size and shape of samples. The material properties of the heat-affected metal at the cut edge might be different from those of the parent metal. Hardness as a very important parameter for the assessment of material properties has been widely used in the design procedure. The Vickers hardness test is a versatile method to measure material hardness in practice. In this study, a comparison of cut-edge hardness between the thermal and mechanical cutting processes was performed on the structural steels S355 and S1100 by using the Vickers hardness test method with a small angle at cut edges to widen the heat-affected zone (HAZ). Based on the measurements, the influence of the Vickers test load on the magnitude and distribution of cut-edge hardness for laser-cut samples of steels S355 and S1100 was clarified. Furthermore, the effects of cutting processes on the hardness were illustrated. Finally, a comparison between the distribution characteristics of the cut-edge hardness of steels S355 and S1100 was made. For structural steel, it is recommended to apply the Vickers hardness testing method with a test load of 1 kpf and with a small angle at cut edges to widen the HAZ and to get reasonable results. The hardness distribution and the maximum for laser- and plasma-cut edges are similar, depending on the material, with a maximum of 450 HV1 for S355N and of 550 HV1 for S1100M.