Study of Stress Relaxation for 5056 Alloy in Vacuum Conditions

Abstract

The aim of the presented work is to establish relationship of behavior of stress relaxation process in 5056 alloy in vacuum conditions for stress levels of 116 MPa, 83 MPa and 50 MPa and temperatures of 293 K and 353 K. Method of circular specimens with equal flexural strength was used as the main method for stress relaxation testing. Results of the studies allowed to develop the advanced methodology for evaluation of stress relaxation, which increases measurement accuracy up to 0.04 MPa. Increase of accuracy was achieved using the proposed new shape of a specimen of equal flexural strength, its manufacturing technology and developed design of accessories for precision marking. It was established that for studied temperatures stress relaxation in vacuum is occurring more intensively independently from level of initial stress. That fact can be explained by increase of influence of dislocation mechanism on stress relaxation. The results of the presented studies serve as a basis for increase of reliability and consistency of dimensions of elements of aircraft's structure and their parts and components, which are operating in vacuum conditions.