1000MW塔式炉水冷壁T23钢接头短期失效分析

发布时间：2018-04-13 23:29

本文选题：USC塔式炉 + 水冷壁　；参考：《中国电机工程学报》2015年S1期

【摘要】：对近年来国内1 000 MW超超临界塔式炉中频发的水冷壁T23接头短期失效案例进行了分析,观察了裂纹的宏观和微观形态,通过OM、SEM和TEM分析了裂纹附近的的显微组织,并测试了接头的力学性能。通过有限元软件模拟了附加应力对裂纹形成的影响。最后在上述此基础上判断裂纹的性质,阐明其形成机理,并提出预防措施。结果表明,裂纹为蠕变沿晶裂纹,沿焊缝横向分布在管子的6点钟或12点钟位置。焊态焊缝形成了较多高硬度的马氏体,其在运行后的室温冲击韧性很低。这种焊缝在水冷壁工作温度下具有蠕变脆性,在结构附加应力和疲劳载荷的作用下易于发生蠕变沿晶开裂。选择低强度等级焊材、进行焊后热处理、细化晶粒和减小水平方向的结构应力有助于抑制裂纹。
[Abstract]:Short-term failure cases of water-wall T23 joints in 1 000 MW ultra-supercritical tower furnace are analyzed in recent years. The macroscopic and microscopic morphology of cracks are observed. The microstructure near the cracks is analyzed by OMSEM and TEM.The mechanical properties of the joint were tested.The effect of additional stress on crack formation is simulated by finite element software.Finally, on the basis of the above, the properties of cracks are judged, the formation mechanism of cracks is clarified, and the preventive measures are put forward.The results show that the crack is a creep intergranular crack, and the transverse distribution of the crack along the weld seam is at 6 o'clock or 12 o'clock in the tube.More martensite with high hardness was formed in the weld, and the impact toughness at room temperature was very low.This kind of weld has creep brittleness at the working temperature of water wall, and creep intergranular cracking is easy to occur under the action of additional stress and fatigue load of the structure.Selecting low strength grade welding materials, heat treatment after welding, refinement of grain size and reduction of structural stress in horizontal direction can help to suppress cracks.
【作者单位】：水力机械过渡过程教育部重点实验室(武汉大学);江苏方天电力技术有限公司;
【基金】：国家自然科学基金项目(51574181)~~
【分类号】：TG441.7;TK175

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