Calculation-experimental analysis of the thermocyclic deformation of titanium nickelide coil springs

Abstract

The physicomechanical behavior of a cylindrical spring made of titanium nickelide is experimentally studied during thermal cycling through the martensitic transformation ranges at a constant tensile force. The spring exhibits a reversible change in the length and the diameter, the relative change in the length reaches 1476%, and the relative change in the diameter is 33%. The alternation of reciprocating rotary motion and translational motion of the spring is observed during deformation. A method is proposed to estimate the stresses and the strains that appear in the material at large spring elongations. Thermal cycling at a constant axial force is shown to be accompanied by a reversible hysteretic change in the tangential and normal stresses and the shear strains and by a reversible hysteretic reversible change in the axial strains.