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本文以高温下的HK-40合金炉管的蠕变断裂失效问题为背景,探讨了描述蠕变裂纹扩展的一个力学参量-高温COD.介绍了在国产蠕变试验机上组建的高温COD测试装置和测试方法;分析了用长焦距显微镜监测到的实验结果和现象;推导和证明了COD速率和C~*之间关系的公式;提出了C形试样的工程估算式.在871℃下,对不同损伤程度的HK-40合金材料,用C形试样进行了蠕变裂纹扩展实验.所得数据用五个力学参量,即应力强度因子K_1、净截面应力σ_(net)、参考应力σ_(ref)、COD速率δ_t、能量率积分C~*进行关联,其结果表明δ_t和C~*能在较大范围内较好地关联HK-40合金裂纹扩展的实验数据.
In this paper, a high-temperature COD test device for creep creep cracking is described, which is based on the creep fracture failure problem of HK-40 alloy furnace tube at high temperatures. Test methods; analysis of the experimental results and phenomena monitored with a long focal length microscope; derivation and validation of the formulas for the relationship between COD rate and C*; and the engineering estimate formula for C-shaped test specimens. At 871°C, The HK-40 alloy material with different degrees of damage was subjected to a creep crack propagation test using a C-shaped specimen. The data obtained used five mechanical parameters, ie, stress intensity factor K_1, net cross-section stress σ_(net), and reference stress σ_(ref). Correlations between COD velocity δ_t and energy rate integral C~* indicate that δ_t and C~* can better correlate the experimental data of HK-40 alloy crack propagation over a wide range.