METHOD FOR EVALUATING CREEP DAMAGE SUITED TO STRESS CONCENTRATION PART OF HIGH Cr STEEL

摘要

PROBLEM TO BE SOLVED: To improve estimation accuracy of a creep damage evaluation method for correcting a creep rupture lifetime by a correction coefficient, thereby dissolving a notch-strengthening phenomenon.SOLUTION: A creep damage evaluation method for tubes of high Cr steel includes: obtaining a principal stress of each part of a tube by stress analysis; calculating a creep rupture lifetime Tr for use in an evaluation of creep damage on the basis of a maximum principal stress 1 in the principal stresses of the respective parts; calculating a multiaxial degree TF on the basis of the obtained principal stresses of the respective parts; obtaining a correction coefficient k corresponding to the calculated multiaxial degree TF using a diagram representing a correlation between the multiaxial degree and the correction coefficient that represents a ratio of the actual creep lifetime to the creep lifetime evaluated by the maximum principal stress; and evaluating the creep damage using the creep rupture lifetime after the correction of the calculated creep rupture lifetime Tr by the correction coefficient k.