The Extrusion Cracks of Inconel 625 Superalloy Tubes Caused by the Primary MC Carbides

Abstract:

Inconel 625 superalloy tubes were hot extruded using a horizontal extruder. Optical microscope, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) technique were employed to investigate the extrusion defects mainly caused by the primary MC carbides. The results showed that a lot of surface cracks, internal cracks, grooves and shrinkage cavity defects existed in the outer surface and internal of the Inconel 625 superalloy tube after hot extrusion. However, the inner surface of the tube was smooth and no cracks were observed. In addition to the external factors during hot extrusion, the cracks are mainly caused by the primary MC carbides or large dimension of C particles formed due to a relatively short smelting time and large dimension of C particles during smelting with the decreasing plasticity of the grain boundary. This kind of cracks can be avoided through improving the uniformity of the chemical composition by reducing the size of C particles and extending the diffusion time during the smelting of Inconel 625 superalloy.

• Periodical: Materials Science Forum (Volume 817)
• Pages: 550-555
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.817.550
• Online since: April 2015
• Authors: Qing Miao Guo*, Zhen Lei Tang, Guo Liang Xie, Jie Hu, De Fu Li
• Keywords: Cracks, Extrusion Defects, Inconel 625 Superalloy, Primary MC Carbides

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