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| Cracking Failure of Carburized Injector Valve of 18CrNi4WA Steel |
| Received:April 27, 2018 Revised:July 25, 2018 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/ issn.1672-9242.2018.07.016 |
| KeyWord:injector valve 18CrNi4WA steel failure analysis |
| Author | Institution |
| WU Shuai |
Southwest Research Institute of Technology and Engineering, Chongqing , China |
| WANG Chang-peng |
Southwest Research Institute of Technology and Engineering, Chongqing , China |
| SU Yan |
Southwest Research Institute of Technology and Engineering, Chongqing , China |
| CHEN Xi-dong |
Southwest Research Institute of Technology and Engineering, Chongqing , China |
| ZHANG Kai |
Southwest Research Institute of Technology and Engineering, Chongqing , China |
| ZHAO Li-yang |
China institute of marine technology and economy, Beijing , China |
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| Abstract: |
| Objective To investigate cracking failure reasons of the carburized injector valve made of 18CrNi4WA steel. Methods The fracture modes and failure reasons of the injector valve were analyzed by means of chemical composition analysis, SEM analysis, metallographic examination and energy spectrum analysis. Results The original material of the needle valve was in conformity with the manufacturing requirement. But due to the high carburizing quenching temperature, the best carburized layer structure was not obtained. The sulfur element in fuel caused serious corrosion of injection holes. Changes of the local pressure in the fuel oil caused cavitation damage on the surface of the needle valve body. The crack began at the circumferential surface of the injection hole and radiated from the crack source to the crescent shape. It was called as typical fatigue fracture. Conclusion Synergistic effects of the corrosion and cavitation damage promote crack initiation and produces fatigue cracking under the action of the thermal-mechanics alternate fatigue load. The service life of the injector valve was greatly reduced. |
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