Constraint Loss Correction between SENB and SENT for Welded Joint Specimens based on Weibull Stress Criterion

摘要

Constraint loss correction procedure using Weibull stress criterion isspecified as ISO 27306 in 2009. This procedure provides critical CTODto brittle fracture in structural component with the defect using thecritical CTOD obtained from standard fracture toughness test specimenthrough the equivalent CTOD ratio β. Although the difference of theplastic constraint condition can be easily revised by using equivalentCTOD ratio β, there are few examples applied to the welded jointevaluation.This paper presents the plastic constraint loss correction betweenSENB and SENT specimens for base plate and weld joint usingequivalent CTOD ratio β. The CTOD in SENT specimen is predictedfrom that in the SENB test results that tested at lower shelf CTODtemperature such as –60℃ based on the critical Weibull stress criterion.Critical Weibull stress is calculated with taking account of internalstress distribution in plate thickness, critical fracture volume along thecrack tip with reference to coarse grain heat affected zone and initialcrack shape. The minimum of three equivalents CTOD in SENT testsshow good agreement with the predicted CTOD from the SENB testresults using this procedure.