Volume 3, Issue 1, March 2019, Page: 20-24
Cause Analysis of Turbine Shaft Ultrasonic Flaw Detection Disqualification
Wang Yongsheng, Department of Chief Engineer’s Office, Dongbei Special Steel Group, Dalian, China
Sun Shengyu, Department of Chief Engineer’s Office, Dongbei Special Steel Group, Dalian, China
Sun Xin, ESR Plant of Dongbei Special Steel Group, Dalian, China
Guo Libo, Central Laboratory of Dongbei Special Steel Group, Dalian, China
Received: Nov. 20, 2018;       Accepted: May 27, 2019;       Published: Jun. 18, 2019
DOI: 10.11648/j.ajmme.20190301.13      View  193      Downloads  27
Abstract
Heavy forging is a kind of large or deformed-size forge, used on marine, roller or power station roter. etc, which are fabricated by free forging or hydraulic compressor. The turbine shaft products, steel grade ASTM668E, rejected during ultrasonic inspection. Aiming at the problem of ultrasonic flaw detection disqualification, through Positioning saw cutting, the macroscopic test, SEM and Micrographic examination are taken out. The main cause of the disqualification were found out. The results show that, because of the exist of unbalance crystallization, highly grade general loosen happened in the cycle area, which cause the energy of ultrasonic are weakened a lot, then lead to the central quality of the forging cannot be detected clearly. What’s more, the manganese sulfide precipitated at the grain boundary because of the selective crystallization occurs in the central of the ingot. The tensile stress on the interface between steel and inclusion separate the steel, caused the cracks which couldn’t be welded as the plastic deformation happened in forging press, then cause the cracks. Reduce the molten steel’s overheat and the freezing time can improve the defect of general loosen and the gartering of low-melting ingredients. Increase the compression ratio can take out too in the hot work process to solve the problem.
Keywords
Heavy Forging, ASTM668E, UT, General Loosen, Manganese Sulfide
To cite this article
Wang Yongsheng, Sun Shengyu, Sun Xin, Guo Libo, Cause Analysis of Turbine Shaft Ultrasonic Flaw Detection Disqualification, American Journal of Mechanical and Materials Engineering. Vol. 3, No. 1, 2019, pp. 20-24. doi: 10.11648/j.ajmme.20190301.13
Copyright
Copyright © 2019 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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