Abstract
The effect of heat input from laser beam welding (LBW) on the microstructural evolution of superalloy Inconel 718 was investigated. LBW was carried out on 1.6-mm-thick sheets with an average grain size of 13 μm (ASTM # 9.5), and four different heat inputs in the range of 74.5 mm-1 to 126.6 J mm-1 were used. Full penetration was achieved in all weld experiments. Microstructures of the welds were evaluated using an optical microscope and a field emission scanning electron microscope. Increasing the heat input changed the resulting weld shape from a wine glass shape to a stemless glass shape with wider surface bead widths, and the measured average dendrite arm spacing was increased from 1.06 μm to 2.30 μm, indicating the corresponding solidification rate in the range of 1.75 × 105 K s-1 (°C s-1) to 3.5 × 106 K s -1 (°C s-1). The welds also were free from microfissuring even at the lowest heat input trials. The Nb concentration of Laves phase for the current LBW samples was ≈20.0 wt pct. The coefficients of partition and distribution for Nb were determined to be approximately 3.40 and 0.50, respectively.
Original language | English |
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Pages (from-to) | 2357-2365 |
Number of pages | 9 |
Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
Volume | 41 |
Issue number | 9 |
DOIs | |
Publication status | Published - Sept 2010 |
Funding
This work was financially supported by the Istanbul Technical University, Turkey, Research Fund (Project #32101). The authors are indebted to Professor T.B. Massalski and his referee team and to Professor Edgar A. Starke, Jr. for their valuable comments and discussion. The authors wish to thank Mr. Huseyin Sezer and Mr. Talat Tamer Alpak for their help and contributions during the SEM analysis of this study. Also, the authors thank Mr. Huseyin Gokcan, Mr. Kubilay Yildirim (GE Marmara Technology Center, Kocaeli, Turkey) for their help during the welding process.
Funders | Funder number |
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Istanbul Teknik Üniversitesi | 32101 |