Identification of magnetomechanical phenomena in a degradation process of loaded steel elements

•Author’s diagnostically useful model approach for stress effected magnetizing was proposed.•Passive magnetic method was used in evaluation of effort state of steel.•Applied algorithm for magnetic effects separation was essential to obtain valuable diagnostic information.•Developed measuring device proofs its ability and effectiveness. The search for new methods of determining the degree of stress of steel structures and the methods of detecting early phases of defect development are still proceeding. These allows to enhance the safety of use of machines and construction structures. The paper presents the description of a measuring apparatus, the method of measurements and the results of the research carried out at test beds with a focus of acquiring new sources of information regarding the technical condition of construction materials. In the long run, such information could prove useful for the diagnosis of objects made of various types of materials that have magnetic properties. Authors points out the basic problems encountered while searching for diagnostic information in magnetic signal, which comes from the complexity of stress effective magnetization. The proper model of magnetization was introduced which leads to original method which based on the special measurement and on dedicated processing of obtained signals. Relevant experiment was performed which concerned a two-dimensional measurement and analysis of own magnetic field of a construction steel sample for three various degrees of effort. The key point was to identify and separate reversible and irreversible magnetomechanical effects according to proposed method. The results proofs of existence of detail diagnostic information which is possible to discover. The results of the research lead to improvement of the existing measuring approach for passive magnetic methods and reduce the risk of omissions of diagnostically valuable diagnostic information. This paper ends with a summary of the obtained results while focusing in particular on the utility value of the approach for the purpose of diagnosis and its further development.