Residual Stresses in the Heat Affected Zones of Flame Cut Steel Plates

Residual stresses may be defined as those stresses which exist in a material free of external load, generally resulting from nonhomogeneous plastic deformation which may be introduced in many ways such as fabrication process, flame cutting, welding etc. During the flame cutting process, there is a rapid change in temperature, resulting in non uniform heating and cooling which not only introduces residual stresses but also causes changes in chemical composition of the material in the region of the edges of cut. When the heat is conducted to the surrounding parent material, rapid rates of cooling are encountered. In addition, the varying degree of affinity of iron and the various alloying elements in steel to oxygen gives rise to changes in the chemical composition of the material in the neighbourhood of the cutting area.