Microstructure of HR6W Alloy at Elevated Temperature after Prolonged Ageing in Air Atmosphere

A. Zielińskia, G. Golańskib, M. Kieratc, M. Srokad, A. Merdab, K. Sówkae aŁukasiewicz Research Network - Institute for Ferrous Metallurgy, K. Miarki 12-14, PL 44100 Gliwice, Poland bCzestochowa University of Technology, Institute of Materials Engineering, Al. Armii Krajowej 19, PL 42200 Częstochowa, Poland cSilesian University of Technology, Institute of Material Science, PL 40019 Katowice, Poland dSilesian University of Technology, Department of Engineering Materials and Biomaterials, PL 44100 Gliwice, Poland eZRE Katowice, Poland

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The article conducts research aimed to determine the impact of long-term ageing (20 000 hours) at 700° and 750° on the microstructure of the HR6W alloy. Research results indicate that long-term exposure to high temperature causes significant changes in the microstructure of the tested alloy. The effect of increasing the ageing temperature to 750° caused a significant acceleration of the precipitation process after just 1000 h. At that time their coagulation and an increase in the size of the Laves phase precipitates inside the austenite grains were observed, apart from the M23C6-type precipitation grids along the austenite grain boundaries. The extension of the ageing time to 20 000 h at 750°, however, contributed to a significant increase in the size of the Laves phase precipitates inside the austenite grains.

DOI:10.12693/APhysPolA.138.253 topics: HR6W, microstructure, alloys, precipitation, ageing