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Description
The development of steel stress coupons, including an amount of residual stresses up to the yield point has been proven useful for the development of the Magnetic Stress Calibration (MASC) Curves [1]. These coupons were developed by autogenous welding in different types of steels in order to compare surface and bulk residual stresses determined by X-ray diffraction in the Bragg – Brentano set-up and nuclear diffraction respectively with magnetic properties in the same volume and direction. A new principle of developing new steel stress coupons is presented in this paper, related to the induction heating and consequent water or oil quenching of the heated steel, keeping the steel coupon pressed to avoid stress-induced bending. This way the residual stress profile includes similar maxima and minima, corresponding to stresses approaching the yield point. The advantage of these new coupons is the ease of manufacturing and the fact that phase transformations are less than for the case of welding. The technology is repeatable, thus allowing for successful interlaboratory tests.
References
[1] P. Vourna, E. Hristoforou, A. Ktena, P. Svec, and E. Mangiorou, “Dependence of Magnetic Permeability on Residual Stresses in Welded Steels,” IEEE Transactions on Magnetics, vol. 53, no. 4. Institute of Electrical and Electronics Engineers (IEEE), pp. 1–4, Apr. 2017. doi: 10.1109/tmag.2016.2628025.
