Alloy 718 has a very long history, it is still used extensively, which accounts for more than 50% of commercial superalloy productions in the world. The reason is that Alloy 718 exhibits good strength, excellent weldability and lastly, but most importantly, reasonable cost. Recently, confocal scanning laser microscope (CSLM) offers a convenient way for conducting a real-time and continuous in-situ observation of phase transformations at high temperatures. Several studies using CSLM have been reported for low carbon steel, stainless steel and metallic glass materials. The aim of this paper is to study the solidification behavior of Alloy 718 using confocal scanning laser microscope. In addition to the in-situ observation of solidification at different cooling rates, the analysis of microstructure evolution was conducted by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show that the cooling rate has a great impact on the solidification behavior of Alloy 718. Variation of secondary dendrite arm spacing, morphology change in MC carbide, nd Laves phase after solidification at different cooling rates are studied in details. (AU) © 2010 by The Materials, Metals, & Materials Society. All rights reserved.
Technical Paper (PDF 1.10 MB)