汽轮机高压缸接管焊缝失效分析

针对某电厂一起高压缸接管焊缝发生的泄漏事故,采用宏观检查、金相分析、X射线能谱分析、力学性能试验、扫描电镜观察等分析手段,查明了焊缝失效原因并提出解决和预防措施。分析结果表明:由于热处理工艺不当导致焊接处应力松弛,该处应力集中的粗晶区域的晶界塑性变形量超过该部位塑性变形的能力,从而产生再热裂纹。复杂的应力-应变因素影响,加.速了焊缝裂纹的扩展和开裂,最终导致焊缝泄漏。

Analysis on welded seam failure of turbine high-pressure cylinder connecting pipe

Aiming at the accident of welded seam leakage of turbine high- pressure cylinderconnecting pipe in a power plant, by the macroscopic detection, metallurgical analysis, X- ray energyspectrum analysis, mechanical performance test and electron microscope scan, etc., finds out thecauses of welded seam failures and puts forward the solution and prevention measure. The analysisresult shows that due to improper thermal treatment technique, brings on the connecting pipe weldsoccuring stress relaxation, in the welds of stress concentration, the plasticity deflection of grainboundary in coarse grained region exceedplasticity deformation ability of the locality, therebyreheating crack takes place. The influence of complex stress- strain factor makes the crack extensionand dehiscence, finally leading to the welds leakage.