【摘要】 生长应力是导致氧化皮开裂或剥落的原因之一,但其研究相对较少。以T91过热器管为研究对象,根据材料的化学成分及氧化皮抛物线氧化动力学速率公式,计算双层氧化皮的厚度。将生长应变引入胡克定律,借助广义平面应变问题的应力平衡关系,推导过热器管氧化皮生长应力的计算模型。内外层氧化皮的不同生长氧化模式导致了不同的位移边界条件。计算结果表明:蒸汽侧氧化皮内环向应力绝对值要远大于径向应力和轴向应力的绝对值,环向应力值越靠近磁铁矿/铁铬尖晶石界面,绝对值越大,界面处容易发生氧化皮的翘曲和剥离;管径越大,氧化皮承受的环向应力和轴向应力值的绝对值越小;随着内压力增加,氧化层承受的环向应力增加;横向氧化应变使氧化皮的环向应力和轴向应力处于压应力状态。更多还原

【Abstract】 The growth stresses of oxide scales may cause the cracking or spallation of oxide scales and the research about it is limited. Considering chemical composition of ferritic-martensitic steel(T91) of superheaters, the thicknesses of double oxide scales are calculated through the parabolic kinetics equation of oxidation. According to the stress balance relation of generalized plane strain problems, the growth strain of oxide scale is introduced to Hooker’s law, and the calculation model of oxidation growth stresses of oxide scale is deduced. The different oxidation modi of the inner and outer layers lead to the different displacement boundary conditions. The results show that the absolute value of circumferential stresses is much larger than that of radial stresses and axial stresses of steam side oxide scale. The absolute value of circumferential stresses is larger when the position is nearer to the magnetite/Fe-Cr spinel interface. The bulking and exfoliation of oxide scale easily happen at this interface. The larger the tube diameter is, the smaller the absolute values of circumferential stresses and axial stresses of oxide scale are. The circumferential stresses of oxide scales rise with increasing pressure. The lateral oxidation-strain components of growth strain have considerable effects on stresses of oxide scales.更多还原