It is known that the main sources of damage during operation of engineering products are local stress concentration zones (SCZs) that are formed under the action of workloads primarily on defects of metallurgical and process nature.
Metallurgical and process manufacturing defects are known to cause high level of residual stresses (RS) in local zones of the product. RS control at some productions is performed on a selective basis. In this case the average (volumetric) level of RS is inspected, and local RS zones due to internal defects of the metal, as a rule, are not inspected and omitted. Besides, the location of these local zones and the method of their detection are unknown.
As a rule, RS control during the incoming inspection is not performed. For these reasons, during the very first years of products operation under the working load their “rejection” takes place. Process and metallurgical defects, causing the high level of RS in local zones of products, at unfavorable combinations with stresses due to working loads cause accelerated development of damages.
At present the products inspection at manufacturing plants and during operation consists in the usual flaw detection without any assessment of stress concentration level on apparent (discontinuity flaws) and implicit (structural) defects.
The metal magnetic memory (MMM) method developed by Energodiagnostika Co. Ltd. (Moscow) becomes more practically implemented for solution of the problem of determination of local SCZs in new and operated products. Russian and International standards on the MMM method are published.
The paper considers the capabilities of the MMM method during the diagnostics of new and operated products in order to detect local SCZs – the sources of damages development. Examples of control of fatigue development and material defects are shown.