延性脆性遷移温度領域における溶接残留応力場中のき裂の脆性破壊発生評価法

摘要

前報において、ワイプル応力仮説に基づく溶接残留応rn力場中のき裂からの脆性破壊発生限界の評価における塑性rn拘束補正方法について報告した。その中では、ワイブル応力rnを破壊駆動力として、標準破壊靭性試験片と残留応力を有すrnる広幅溶接継手が同じワイブル応力を呈するき裂先端開口rn変位（CTOD）レベルに着目した評価手法を検討した。%This paper presents the methodology of the CTOD fracture toughness correction for wide plates' welded joints from lower to upper ductile-brittle transition temperature region. Tensile plastic zone size criterion is adopted in lower transition region. The equivalent CTOD ratio, β_r , is adopted in ductile-brittle transition and upper transition region. The equivalent CTOD ratio is defined as the ratio of CTOD in a standard fracture toughness specimen to CTOD in a wide plate with welding residual stress at the same level of the Weibull stress. Fracture assessments for "After Weld Notch" and "Before Weld Notch" type welded joints have been conducted by applying the toughness correction methodology. It has been found that an excessive conservatism observed in the conventional procedure is reasonably reduced by applying the proposed methodology.