期刊
OPTICS AND LASERS IN ENGINEERING
卷 49, 期 9-10, 页码 1101-1110出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.optlaseng.2011.05.016
关键词
Direct laser forming; Steam turbine blade; Laser specific energy; Powder feeding rate; Columnar crystal
类别
资金
- State Basic Research Key Projects (973) of China [2007CB707704]
- Program for Changjiang Scholars and Innovative Research Team in University [PCSIRT0646]
- National Natural Science Foundation of China [51005177]
- Fundamental Research Funds for the Central Universities
In order to achieve high precision and unidirectional solidification microstructure of steam turbine blade fabricated by direct laser forming (DLF), this study is focused on the influence of the laser scanning speed, specific energy and powder feeding rate on the forming characteristics of single cladding pass, which is elementary units in DLF, and a new method of columnar crystal preparation is investigated. Results show that both the metal powder stream and the laser specific energy are the most important factors, that control the high temperature behavior of molten pool so as to determine the micro-morphology of laser scanning track. Based on the optimum processing conditions, high definition steam turbine blade of 316L is fabricated (surface roughness Ra of 10.08 to 26.51 mu m or so). The microstructure is of fish scale type by natural cooling after DLF, but it is first found that columnar crystals can be formed on the non-columnar crystal substrate of 316L by intermittent cooling with liquid argon. Therefore, the above investigations will benefit the rapid development of steam turbine blade. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.
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