Advanced microstructural characterisation of cast ATI 718Plus®—effect of homogenisation heat treatments on secondary phases and repair welding behaviour
Journal article, 2020

The influence of base metal conditions on the weld cracking behaviour of castATI 718Plus® is investigated by comparing 4 h and
24 h dwell time pseudo-hip homogenisation heat treatments at 1120, 1160 and 1190 °C with the as-cast microstructure. Scanning
electron microscopy (SEM), X-ray diffraction (XRD) on electrolytically extracted powder and transmission electron microscopy
(TEM) were used to identify Nb-rich secondary phases in interdendritic areas as the C14 Laves phase and Nb(Ti) MC-type
carbides. All homogenisation heat treatments but the 1120 °C 4-h condition dissolve the Laves phase. A repair welding operation
was simulated by linear groove multi-pass manual gas tungsten arc welding (GTAW). The Laves phase containing microstructures
resulted in lower total crack length for heat affected zone cracking. Constitutional liquation of Nb(Ti) MC-type carbides is
observed as a liquation mechanism in Laves-free microstructure, while thick liquid film formation due to the Laves eutectic
melting could reduce the formation of weld cracks in microstructures containing the Laves phase.

weldability

cracking

repair

nickel alloys

GTAwelding

ATI 718Plus

Author

Fabian Hanning

Chalmers, Industrial and Materials Science, Materials and manufacture

Abdul Khaliq Khan

University of Manitoba

Joel Andersson

University West

Olanrewaju Ojo

University of Manitoba

Welding in the World, Le Soudage Dans Le Monde

0043-2288 (ISSN)

Vol. 64 3 523-533

Subject Categories

Manufacturing, Surface and Joining Technology

Other Materials Engineering

Metallurgy and Metallic Materials

Areas of Advance

Materials Science

DOI

10.1007/s40194-020-00851-0

More information

Latest update

1/21/2021