The residual stresses that generates upon carburising and hardening are allowed to undergo a relaxation process, and produce a curveture in 080M15 steel bars. The degree of curveture is found to vary depending upon the carbon distribution. The fibre stress necessary to reduce the deflection to zero is evaluated and related to the surface residual stresses. The residual stresses incarburised & hardened 080M15 steel is fund compressive when decarburisation is not allowed to take place, and tensile upon the occurance of decarburisation Carburising conditions are veried to produce different carbon profiles, that influence the residual stress pottern. The highest compressive residual stresses of 661 MN/m² resulted from boost-diffuse carburising, in which the carbon content of 0.8% is maintained constant to a depth of 0.3mm. Compressive residual stresses are lowered upon the occurance of retained austenite and even further when carbides are also formed.