航空发动机高压涡轮工作叶片阻尼叶冠表面堆焊耐磨层后，发现焊接热影响区存在延迟裂纹。通过基体材料成分分析、金相观察、扫描电镜分析等手段分析裂纹原因，结果表明：裂纹为焊接及磨削残余应力与时效组织应力叠加导致应变集中产生的应变-时效裂纹。通过增加焊前预热、焊后缓冷、焊后立即退火、控制叶片磨削进刀量等措施有效降低裂纹故障率。冷热循环试验表明在正常工作过程中叶片裂纹扩展速率缓慢，一般不会形成封闭裂纹；叶冠边缘处裂纹有向叶冠外侧扩展倾向，可能造成掉块，影响飞行安全。%Some delayed cracks were found at welding heat affected zone after wear-resistant layer was welded on damping shroud surface of high pressure turbine blade. The cause of cracks was analyzed by chemical composition analysis, metallographic microscopy and SEM observation. The results show that the strain concentration in the overheated zone caused by the comprehensive effect of residual welding and grinding stresses and aging microstructure stress resulted in strain aging crack in the grain boundary. By preheating before welding, cooling slowly and annealing immediately after welding, controlling blade grinding feed and other measures, the crack failure rate can be effectively reduced. The cold and thermal cycling test indicated that the cracks were unlikely to turn into closed cracks because the cracks' propagation rate is slow under normal work condition, but the cracks on the edge had a tendency to extend to be closed, affecting the flight safety.
展开▼
