工业锅炉水冷壁管裂纹产生原因分析

The Analysis on the Causes of Industrial Boiler Water Wall Tube Cracks

通过外观检查、厚度、硬度测试和金相分析等试验方法,证实水冷壁管环向裂纹产生的原因是由于锅炉的水循环偏差和受热面受热偏差引起的高温区水冷壁管内部工质汽化,金属表面周期性超温,导致管子承受周期性交变热应力和高温氧化作用,进而形成表面脱碳、显微组织粗化、同时产生管子内外部腐蚀减薄,金属强度降低;在交变热应力和蠕变应力作用下,在管外侧向火侧产生疲劳裂纹和蠕变变形,管子局部发生胀粗减薄,裂纹逐渐扩展,最后形成穿透性环状裂纹.

By the methods of visual examination, thickness and hardness measurement, metallographic analysis. The causes of the water wall tube circumferential cracks are boiler water circulation deviation and the heating surface heating deviation, duo to high temperature zone water wall tube internal working fluid vaporized and metal surface periodic over-temperature, which cause the pipe to withstand cycle alternating thermal stress and high temperature oxidation. Thus the formation of surface decarburization, microstrueture coarsening, generated both inside and outside of the tube corrosion is thin and metal strength decrease.