Residual Stresses in Bent Tubes for Nuclear Steam Generators^★

Residual stresses in Inconel 600 tubes for PWR steam generators were measured using the strain gauge technique, and the results were checked by a stress corrosion test in boiling MgCl₂ performed on stainless steel tubes manufactured according to the same process as the Inconel 600 tubes. It was shown that very high tensile stresses, equal to or even exceeding the yield stress, could exist as a result of the straightening, bending or roll expanding operations. The efficiency of possible stress relieving treatments was also investigated.