METHOD OF METAL RESIDUAL LIFE EVALUATION OF OPERATED STEEL PIPES Russian patent published in 2008 - IPC G01N3/00 

FIELD: physics.

SUBSTANCE: pipe section of greatest coercive force is blanked. Blanks are deformed and artificially aged. Coercive force is measured. Patterns are prepared and tested. Deformation dependence of pipe metal mechanical parametric variation is approximated. Pipe metal mechanical parametric documentation is chosen. Operation deformation ε_o is evaluated. Minimal plastic flow increment Δε_"кр" is evaluated. Values ε_"э" and Δε_"кр" and certain operation life are used to calculate residual life. Minimal plastic flow increment Δε_"кр" is evaluated by sequential step deformation of blanks implying that each deformation step followed by artificial aging of blanks and evaluation of increment deformation. Value Δε_"кр" is evaluated by approximating dependence in which mechanical parameter reaches specified level. Value ε_o is evaluated through measuring coercive force of one blank "Н^э _с"_{corresponding to coercive force of pipe metal at the testing, recovery of metal properties until coercive force corresponds to coercive force of pipe metal at the mounting "Н^э с", subsequent step deformation and artificial aging of blank and evaluation of increment plastic deformation after each deformation step. Value ε"э" is evaluated by approximating plastic deformation dependence of metal coercive force variation as total increment of plastic deformation with coercive force variation within "Н^о с" to "Н^э с".}

EFFECT: higher testing reliability.