基于多模主曲线法估计韧脆转变区间热影响区断裂韧度

Estimation of fracture toughness of heat affected zone in ductile-to-brittle transition zone based on multimodal master curve method

标准主曲线法受限于用来准确评估不均质材料的断裂韧度以及对材料进行完整的概率描述。可实际上厚截面钢板、焊接接头不可避免会存在截面性能不均匀。以SA738Gr.B埋弧焊焊接热影响区实测韧性数据为研究对象,分析标准主曲线法的不足之处,并消化吸收了2019版ASTM E1921标准中新增补的多模主曲线法,探讨多模主曲线法分析过程,并把复杂的数值过程通过MATLAB编程实现。研究表明,不均质材料热影响区断裂韧度的数据分散性大,套用标准主曲线法会带来非保守的估计。而多模主曲线法则成功地描述了微观结构不均匀的焊接热影响区转变区间的断裂韧度,多模主曲线法可以容纳由不均质导致的过大分散性,5%容许失效边界曲线可以包络所有测试数据点,并产生相对保守的估计结果。

The standard master curve method is limited to the accurate assessment of the fracture toughness of heterogeneous materials and the complete probability description of materials.In fact,thick section steel plates and welded joints will inevitably produce uneven section performance.The measured toughness data of SA738Gr.B submerged arc welding heat affected zone was used as the research object to analyze the shortcomings of the standard master curve method.Furthermore,the multimodal master curve method newly added in the 2019 version of ASTM E1921 standard was absorbed and digested,the analysis process of the master curve method was discussed,and the complex numerical process was realized by MATLAB programming.Studies show that the fracture toughness data of the heat-affected zone of heterogeneous materials was highly dispersed,and applying the standard master curve method would bring non-conservative estimates.Whereas the multimodal master curve method successfully described the fracture toughness of the transition zone of the welding heat affected zone with uneven microstructure.The method can accommodate the excessive dispersion caused by inhomogeneity,and the 5%allowable failure boundary curve can envelop all test data points and produce relatively conservative estimates.