TP304不锈钢三通失效分析

电厂脱硝设施中所使用的TP304不锈钢三通出现裂纹缺陷，通过成分分析、断口宏观和微观分析、微观组织观察、硬度检测，并结合生产工艺对三通裂纹的产生原因进行分析。研究结果表明：材料中Ni含量偏低使材料的奥氏体稳定化程度降低；基体内含有的2.5~3.0级球状非金属夹杂物对基体造成撕裂作用，促进疲劳裂纹的萌生；同时，三通在加工完成后也缺少固溶处理步骤，使得材料内应力过大。这些原因综合导致材料奥氏体含量降低，硬度过高，同时造成材料塑性变形部位内应力过高，在支管颈部产生较大的应力集中现象。三通内表面同时存在大量加工损伤，强化了应力集中现象，在疲劳载荷的作用下，促进了三通裂纹的萌生。

Failure Analysis of TP304 Stainless Steel Tee

Cracks formed in a TP304 stainless steel tee in the denitration facilities of a power plant. The failure cause of the tee was studied by means of composition analysis, macroscopic and microscopic analysis, microstructure observation and hardness measurement, as well as production process analysis. The results show that the Ni content of material is lower than the standard requirement, which reduced the stabilization degree of austenite. Spherical non-metallic inclusions with the scale of 2. 5~3. 0 in the substrate had tearing effect on matrix and promoted the initiation of fatigue crack. There is also no solid solution treatment in the production, resulting in excessive internal stress. The factors above led to the lower content of austenite, higher hardness, and higher local stress concentration. In addition, there are lots of processing damages on the inner surface of tee, aggravating the stress concentration phenomenon. Ultimately, under the action of fatigue load, the crack initiated.