Study of the Properties of the Base Metal of Large-Diameter Pipes Under Alternating Loading

A method is developed for evaluating changes in the mechanical properties of the base metal of largediameter pipes during alternating loading. Specimens prepared from rolled products of steels in strength classes K52, K60, and K65 were used to study the effect of sign-changing deformation with the amplitude 0.5/1.0/1.5%. It is shown that plastic deformation at the microscopic level during alternating loading diminishes the elastic properties of these steels. The reduction in elastic properties becomes larger as the strength of the steel increases.