On the Microstructure of Alloy 625 Produced by Laser AM





Introduction: Additive manufacturing (AM) or rapid prototyping technique is based on layer-by-layer growth, fusing thin layers of loose powder with a scanning laser beam, for constructing three-dimensional (3D) shaped objects [1]. This method has grown quickly as an alternative manufacturing route to produce components because of its high process speed, easy processing and production of complex-shaped metallic components. During the construction of a component using AM, the material is submitted to a thermal cycle which involves abrupt heating over the melting point due the absorption of the laser energy followed by a fast solidification of the melted material. Once the heat source moves, several reheating and cooling occur as a consequence of the following layers deposition. Therefore, AM process may lead to metastable microstructures which may vary to each deposited layer [2].

Alloy 625, a solid-solution and precipitation-strengthened nickel-base alloy, is extensively used in industrial applications that require a combination of excellent creep and high corrosion resistance at temperatures below 800°C [3].

This study reports the microstructural characteristics of an Alloy 625 sample produced through Direct Melting Deposition (DMD). The microstructure produced through DMD for this alloy mostly consists of columnar grains. The grain size can change depending on the heat input provided and on the cooling rate, growth direction of the grains is tied to the build direction and to the direction of laser scan [4, 5].

Authors: Cilene Labre, André Luiz Pinto, M. Grace Burke, and Guillermo Solórzano

Keywords:  Additive Manufacturing, Alloy 625, Microstructure

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6 pages