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目前高温断裂力学参量的推定主要是基于材料均匀性的假定 ,但在工程实际中却无法回避由焊接引发的材料不均质问题。在存在焊接界面的情况下 ,如何得到可靠的高温断裂力学参量以合理描述蠕变裂纹的扩展 ,是结构完整性评价所面临的挑战。作者研究材料性能不匹配对单轴带焊缝试样的应力场及时间相关断裂力学参量的影响 ,检验了基于加载线位移的C 估算公式的适用性。计算表明在大范围蠕变条件下带硬焊缝试样的C 值比单一焊缝金属的C 值要高得多 ,而在小范围蠕变条件下材性不匹配对C(t)的影响极小。为此建议对ASTME145 7推荐的C 计算式进行修正 ,以正确演绎焊接试样的蠕变裂纹扩展行为。
At present, the presumption of high-temperature fracture mechanics parameters is mainly based on the assumption of material homogeneity, but in engineering practice, it can not avoid the problem of material inhomogeneity caused by welding. In the presence of a welding interface, how to obtain reliable high-temperature fracture mechanics parameters to reasonably describe the expansion of creep cracks is a challenge to structural integrity evaluation. The authors studied the influence of material mismatch on the stress field and time-dependent fracture mechanics parameters of uniaxial welded specimens, and tested the applicability of C estimation formula based on loading line displacement. Calculations show that the C value of brazed specimens with a wide range of creep is much higher than the C value of a single weld metal and the effect of material mismatch on C (t) under small creep conditions Very small. To this end, it is suggested to amend the C calculation formula recommended by ASTM E1457 to correctly deduce the creep crack growth behavior of welded specimens.