| HUANG Jin-yang,ZHONG Qiang,HUANG Hao-gang,LEI Zhong-hui,WANG Peng,ZHANG Xing-xing,DANG Ying-ying,LU Jin-tao,GU Yue-feng.Slurry Aluminide Coatings on Boiler Tubes for Overheater/Reheater Application(Ⅲ):Field Testing[J],50(7):328-336 |
| Slurry Aluminide Coatings on Boiler Tubes for Overheater/Reheater Application(Ⅲ):Field Testing |
| Received:January 19, 2021 Revised:March 24, 2021 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2021.07.034 |
| KeyWord:field testing coated boiler tube Super304H steam oxidation microstructure strength |
| Author | Institution |
| HUANG Jin-yang |
National Engineering Research Center of Clean Coal Combustion for Utility Boilers, Xi′an Thermal Power Research Institute Co., Ltd, Xi′an , China |
| ZHONG Qiang |
Huaneng Hunan Yueyang Power Generation Co., Ltd, Yueyang , China |
| HUANG Hao-gang |
Huaneng Hunan Yueyang Power Generation Co., Ltd, Yueyang , China |
| LEI Zhong-hui |
Huaneng Hunan Yueyang Power Generation Co., Ltd, Yueyang , China |
| WANG Peng |
Huaneng Hunan Yueyang Power Generation Co., Ltd, Yueyang , China |
| ZHANG Xing-xing |
Xi′an Yitong Thermal Technology Service Co., Ltd, Xi′an , China |
| DANG Ying-ying |
National Engineering Research Center of Clean Coal Combustion for Utility Boilers, Xi′an Thermal Power Research Institute Co., Ltd, Xi′an , China |
| LU Jin-tao |
National Engineering Research Center of Clean Coal Combustion for Utility Boilers, Xi′an Thermal Power Research Institute Co., Ltd, Xi′an , China |
| GU Yue-feng |
National Engineering Research Center of Clean Coal Combustion for Utility Boilers, Xi′an Thermal Power Research Institute Co., Ltd, Xi′an , China |
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| Abstract: |
| In order to verify the combination property of the steam oxidation resistance coating boiler tube under field testing conditions, the coated tube and reference tubes (Super304H and Super304H-peening) were welded on the same temperature tube screen section of the high temperature end superheater in boiler. The integrated performance of the tested tubes were evaluated after serving for 8600 h, respectively. The results indicated that the coated tube showed an extremely excellent oxidation resistance performance. The protective Al2O3 film with a thickness of only about 0.3 μm grew on the inner surface of the coated tube, while the oxidation film thickness of the reference tubes, the Super304H-peening and Super304H, were respectively 0.55 μm and 64.31 μm. After field testing, the double layer coating microstructure was still retained on the surface of the coated tube, also the thickness and average hardness of the coating all increased by 4.5% and 8.1%. In contrast, the thickness and average hardness of the shot-peened layer all decreased by 21.3% and 32% because of the disappearance of a part of twin boundaries and the growth of the broken grain on Super304H-peening tube. At 650 ℃, the tensile test results showed that the high temperature strength of the coated tube were equal to the base material super304H after field testing. The weld microstructure of the coated tube with superheater tubes had a good stability during field testing, and the Al pollution caused by diffusion was not found in the weld zone by line scanning of EDS after welding and serving. The tensile fracture of the weld joints occurred on the coating side. The oxidation resistance performance of the coated tube was improved effectively compared with the Super304H-peening and Super304H tubes, also the film was thinner and the growth rate was slower. The hardness of the coated tube inner surface was increased significantly by preparing coating on the surface of Super304H tube. The coating did not have a significant effect on the high temperature strength, the microstructure of the serviced Super304H tube and the microstructure stability of the welding after field testing. |
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