Dilatometric Method for the Determination of Internal Stresses in Metals and Alloys

Abstract

Internal stresses are known to arise in metals and alloys upon technological processing. They are generally attributed to the nonuniformity of the deformation caused by thermo mechanical treatment of materials. The problem of the determination of internal stresses in structural materials is still urgent. In the dilatometric studies, the detectable feature of the development of inelastic relaxation recovery processes in the deformed material is the opening of dilatometric hysteresis loop, i.e., a mismatch of the temperature dependences of deformation upon heating and cooling. The shape of the dilatometric hysteresis loop and the area bounded by the loop may serve as a quantitative measure of the material inelasticity caused by irreversible structural changes. The difference between the ordinates of the heating and cooling branches of the dilatometric hysteresis loop at any temperature is numerically equal to the plastic deformation resulting from recovery processes in the sample