Feasibility of NDT of ferromagnetic steel structures based on measurements of residual magnetization as a function of elastic stress

摘要

Algorithms for estimating elastic stress in ferromagnetic steel structures are based on measurements of the residual magnetization M{sub}r as a function of tensile and compressive stress σ{sub}0 after quenching and tempering at different temperatures T{sub}(tem). The suggested testing technique is highly sensitive because the range of M{sub}r(σ{sub}0) is fairly wide (for the interval O.6σ{sub}y≥σ{sub}0≥-0.6σ{sub}0, where σ{sub}y is the yield limit, the range is 600-800 kA/m). The necessary condition for using this testing technique is the availability of calibration curves for the selected testing algorithm measured on samples of steels to be tested (i.e., of the same sort of steel tempered at the same temperature). All the testing algorithms suggested in the paper enable one to determine both the magnitude and sign of the stress in the material.