| 王进佳, 何杨烨, 张玉, 高杰, 樊林栋, 毛毅轩, 段梦兰.C形LNG储罐9Ni钢焊缝断裂韧性与裂尖拘束的关联研究[J].海洋工程,2025,(4):207~218 |
| C形LNG储罐9Ni钢焊缝断裂韧性与裂尖拘束的关联研究 |
| Investigation of the relationship between fracture toughness and crack tip constraint for 9Ni steel weld in type-C LNG storage tank |
| 投稿时间：2024-07-04 |
| DOI：10.16483/j.issn.1005-9865.2025.04.018 |
| 中文关键词: 9Ni钢 焊缝 裂尖张开位移 裂尖拘束 有限元模型 |
| 英文关键词:9Ni steel weld crack tip opening displacement (CTOD) crack tip constraint finite element model |
| 基金项目:国家自然科学基金资助项目（52222111） |
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| 摘要点击次数: 10 |
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| 中文摘要: |
| C形LNG储罐存在大量被视为薄弱环节的焊缝区域，所以对9Ni钢焊缝进行断裂评估至关重要。作为断裂评估的核心参数，需要准确获得材料的断裂韧性水平。由于断裂韧性与裂尖拘束状态密切相关，因此亟须探明断裂韧性与裂尖拘束的定量关系。文章基于细观损伤力学理论，建立单边缺口弯曲试件（SENB）的裂纹扩展阻力有限元模型，通过与试验结果进行对比分析，验证了有限元模型的准确性。采用裂尖张开位移δ（CTOD）及裂尖等效塑性应变区面积Ap作为断裂韧性及裂尖拘束的表征参数，研究了材料参数（硬化系数、强度匹配系数）和几何尺寸参数（裂纹深度、试件厚度）对材料断裂韧性及裂尖拘束的影响规律。利用ABAQUS二次开发技术建立9Ni钢焊缝试件断裂韧性和裂尖拘束的数值结果数据库，获取试件不同的裂尖拘束状态及对应的断裂韧性，构建9Ni钢焊缝断裂韧性与裂尖拘束的定量统一关联，准确获得9Ni钢焊缝的断裂韧性水平。研究表明：提高材料的硬化系数和焊缝的强度匹配系数，均能降低裂尖拘束度并提高焊缝的断裂韧性；增大裂纹深度和试件厚度均会提高裂尖拘束度并降低焊缝的断裂韧性；相较于裂纹深度，试件厚度对焊缝断裂韧性的影响程度低。拟合得到的关系式可准确描述9Ni钢焊缝断裂韧性与裂尖拘束的统一关联，能为C形LNG储罐的断裂评估时焊缝断裂韧性的确定提供工程参考。 |
| 英文摘要: |
| There are numerous welds considered as weak areas in type-C LNG storage tanks, so it is crucial to conduct a fracture assessment of 9Ni steel welds. As a core parameter of fracture assessment, it is necessary to accurately determine the fracture toughness level of the material. Since fracture toughness is closely related to the state of crack tip constraint, it is vital to establish a quantitative relationship between fracture toughness and crack tip constraint. Based on the theory of microscopic damage mechanics, the paper establishes finite element models of crack propagation resistance for single edge notch bending (SENB) specimens and verifies their accuracy through comparison with experimental results. Using crack tip opening displacement (CTOD) and the area of the crack tip equivalent plastic strain zone Ap as characterization parameters for fracture toughness and crack tip constraint, the effects of material parameters (hardening exponent, strength matching coefficient) and geometric parameters (crack depth, specimen thickness) on fracture toughness and crack tip constraint are investigated. By utilizing Abaqus scripting, a numerical database of fracture toughness and crack tip constraint for 9Ni steel weld specimens is developed. This allows for the identification of various crack tip constraint states and their corresponding fracture toughness, leading to the construction of a unified quantitative relationship between fracture toughness and crack tip constraint for 9Ni steel welds. The results indicate that increasing the hardening exponent and the strength matching coefficient reduces crack tip constraint and improves the fracture toughness of the weld; increasing crack depth and specimen thickness raises crack tip constraint and decreases weld fracture toughness. Compared with crack depth, specimen thickness has a lesser effect on weld fracture toughness. The fitted formula proposed in this paper accurately describes the unified relationship between fracture toughness and crack tip constraint in 9Ni steel welds, and can serve as an engineering reference for determining weld fracture toughness during fracture assessment of type-C LNG storage tanks. |
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