Detection of local stress concentration zones in engineering products—the lacking link in the non-destructive testing system

Abstract

It is known that one of the main sources of damage during operation of machine-building products are local stress concentration zones (SCZ) that form under the action of workloads primarily on defects of metallurgical and process nature. Sizes of these SCZ vary from several tens of microns to several millimeters. Furthermore, it is unknown where these local areas are located and how they can be found. At the same time, the reject levels of the applied conventional non-destructive testing (NDT) methods at manufacturing plants significantly exceed the sizes of some metallurgical defects. At present, a fundamentally new NDT method based on the use of the magnetic memory of metal (MMM) is more commonly applied in practice. It uses the natural magnetization formed during the products fabrication. The article considers the capabilities of the MMM method for inspection of machine-building products quality by structural inhomogeneity and residual stresses.