Introduction. Complexity of welded joints nondestructive testing under operation conditions is associated with the heterogeneity of the metal structure within the heat-affected zone, which is a stress concentrator; the metal structure in this zone is being changed under cyclic loads. The work aim was to investigate the possibility of applying a coercimetry method to diagnostics of welds working under cyclic loads. Method. At low-cycle fatigue irreversible damage accumulation takes place even in a defect-free weld. The magnetic structurescope KRM-Ts-K2M was used for detection of this damage by the value of the coercive force increase. The impact of load parameters on a coercive force was studied on the basis of static and cyclic testing of samples with butt and fillet (T-shaped) welds. Results. Numerous static and cyclic testing of welds and base metal have enabled the author to determine correlation between a coercive force value and weld resource parameters for the conventional steel grades St3sp, 09G2S and 10KhSND. Prospects of small (with the base ≤ 20 mm) sensors application for weld local diagnostics has also been shown in the work. Conclusion. Combination of magnetic structural testing by a coercive force method with an ultrasonic inspection makes it possible to predict a physical resource of metal work at the examination of hazardous production facilities.
magnetic structural testing, coercive force, steel, welds, static and cyclic load, resource evaluation
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