Issue << content << Magnetic Inspection of Welds Fatigue Resistance

DOI: 10.12737/15091

2015. Vol.18. No. 4, pp. 17-21

Magnetic Inspection of Welds Fatigue Resistance

B. E. Popov

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.
Keywords: magnetic structural testing, coercive force, steel, welds, static and cyclic load, resource evaluation
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