X-ray Diffraction Method in the Study of a Metal Surface Stress State Under Static and Impact Deformation

Abstract

Study of the stress field in a plastic imprint and around it is of great practical importance. Processes similar to indentation are used in shot blasting to harden the surface of materials and generate compressive stresses in the surface layers. The purpose of this work was to study the change in the stress-strain state in the area of the plastic imprint with increasing load, in the transition from small to large deformations, as well as to study the change in stress at different strain rates.X-ray diffraction method was used to study the field of residual stresses generated on the surface of a plastically deformed region – in the zone of an imprint formed when a spherical indenter is pressed into the metal. An analysis of the change in the stress distribution with increasing load in the range of plastic imprint depths of 10–60 µm for steels and aluminum was made. Influence of the loading rate on the change in the values of residual stresses under normal contact of colliding bodies was studied. It is shown that the stress distribution has a complex character with areas of compression and tension of the metal and is determined by the ratio of the indentation depth to its diameter.The obtained experimental data make it possible to determine the choice of optimal modes of shot blasting, including for increasing the endurance limit of products.

Keywords

• deformation
• mechanical stress distribution
• static and dynamic indentation
• x-ray diffraction
• surface