Microstructure evolution of the Gleeble-simulated heat-affected zone of Ni-based superalloy

¹ AGH University of Science and Technology, Faculty of Metals Engineering and Industrial Computer Science, Mickiewicza 30, 30-059 Krakow, Poland
² Chalmers University of Technology, Department of Industrial and Materials Science, 41296 Gothenburg, Sweden
³ University West, Department of Engineering Science, Gustava Melins Gata 2, 46132 Trollhättan, Sweden
⁴ Lukasiewicz Research Network-Foundry Research Institute, Zakopianska 73, 30-418 Krakow, Poland
⁵ Consolidated Precision Products Corporation, Investment Casting Division, Hetmanska 120, 35-078 Rzeszow, Poland

^* Corresponding author: lrakoczy@agh.edu.pl

Abstract

The formation of liquation cracking in a simulated heat affected zone of René108 is reported. The stress controlled thermo-mechanical experiments were carried out on a Gleeble®3800 testing system. The base alloy was lost-wax cast and then solution treated and aged. Light and scanning electron microscopy of this material revealed high volume fraction of γ' precipitates in the dendrite arms and residual eutectic γ/γ' islands in the interdendritic areas. As a result of short-term exposure to high homologous temperature, the volume fraction of γ' phase was significantly decreased due to the dissolution of precipitates in the surrounding matrix. The thin non-equilibrium liquid film, formed locally along grain boundaries, was a key-factor favoring initiation of cracks and their spreading during the Gleeble testing. The liquid appeared as a result of constitutional liquation, mainly of the γ' precipitates.