This work addresses an experimental investigation of the cleavage fracture behavior for ASTM A572 Grade 50 steel welds fabricated by different welding processes. A primary purpose of this study is to examine a correlation approach to evaluate fracture toughness values of steel welds based on Charpy V-notch (CVN) impact energy data thereby enlarging existing relationships between fracture toughness and CVN energy. Fracture toughness testing conducted on three-point bend SE(B) specimens having a weld centerline notch provides the cleavage fracture resistance data in terms of the J-integral at cleavage instability, $J_c$, for the steel welds, including the baseplate material. Conventional Charpy tests produce further experimental data which serve to characterize the ductile-to-brittle transition of the tested steel welds and the CVN energy correlation with fracture toughness data derived from conventional correlation formulas. A statistical analysis based on the Master Curve methodology conducted on the experimentally measured fracture toughness data provides the reference temperature for the tested materials from which estimates of fracture toughness based on CVN energy can be made. The results suggest that current correlations between $T_0$ and the CVN energy may provide nonconservative fracture toughness estimates and, thus, should be modified when the primary purpose is to ensure adequate safety levels, as usually required in flaw assessment procedures.

这项工作是针对通过不同焊接工艺制造的ASTM A572 50级钢焊缝的解理断裂行为的实验研究。这项研究的主要目的是研究一种基于夏比V型缺口（CVN）冲击能数据评估钢焊缝断裂韧性值的相关方法，从而扩大断裂韧性与CVN能量之间的现有关系。对具有焊缝中心线刻痕的三点弯曲SE（B）试样进行的断裂韧性测试提供了在断裂不稳定性下的J积分形式的断裂抗断裂强度数据，${Ĵ}_C$，用于钢焊缝，包括底板材料。常规的夏比试验会产生更多的实验数据，这些数据可用来表征被测钢焊缝的韧性到脆性转变以及CVN能量相关性，以及从常规相关性公式得出的断裂韧性数据。在实验测量的断裂韧性数据的基础上，基于主曲线方法进行的统计分析为被测材料提供了参考温度，从中可以基于CVN能量估算断裂韧性。结果表明，目前之间的相关性${Ť}_0$ CVN能量可能会提供非保守的断裂韧性估算值，因此，当主要目的是确保足够的安全级别时（如缺陷评估程序通常所要求的），应对其进行修改。