Role of Steel Plate Thickness on the Residual Stress Formation and Cracking Behavior During Flame Cutting

Thick wear-resistant steel plates are utilized in challenging applications, which require a high hardness and toughness. However, utilization of the thick plates is problematic as they often have nonuniform mechanical properties along the thickness direction due to the manufacturing-induced segregations. In addition, the processing of thick plates commonly involves flame cutting, which causes several challenges. Flame cutting forms a heat-affected zone and generates high residual stresses during the cutting process. In the worst case, flame cutting causes cracking of the cut edge. The aim of this study is to investigate the role of plate thickness on the residual stress formation and cracking behavior when utilizing flame cutting. Residual stress profiles are measured by X-ray diffraction, plates and cut edges and are mechanically tested and characterized by electron microscopy. The results show that thicker plates generate more unfavorable residual stress state during flame cutting. Thick plates also contain segregations, which have decreased mechanical properties. The combination of high residual tensile stresses and segregations increase the risk of cracking during flame cutting. To prevent the cracking, the residual stresses should be lowered by lower cutting speeds and preheating. In addition, manufacturing practices should be aimed at lowering segregation formation in thick plates.