The Effect of Dilution on HAZ Liquation Cracking in PTAW Ni-base Superalloys Overlay Deposit

• Published in: ISIJ International Vol. 42; no. 2; pp. 178 - 183
• Main Authors: Yoon, Byoung Hyun, Ahn, Yong Soo, Lee, Chang Hee
• Format: Journal Article
• Language: English
• Published: Tokyo The Iron and Steel Institute of Japan 01.01.2002; Iron and Steel Institute of Japan
• Subjects: Applied sciences; dilution; Exact sciences and technology; HAZ liquation cracking; Inconel 625; Inconel 718; Joining, thermal cutting: metallurgical aspects; Metals. Metallurgy; PTAW (plasma transferred arc welding); Varestraint test; Welding; Nickel base alloys; Scanning electron microscopy; Superalloy; Liquation cracking; Plasma welding; Welding; Cracking; Heat affected zone; Experimental study
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.42.178

In this study, the effects of dilution on the HAZ liquation cracking susceptibility of PTAW (Plasma Transferred Arc Welding) Inconel 625 and Inconel 718 overlay on Nimonic 80A were observed. In order to evaluate the HAZ liquation cracking susceptibility, the Varestraint test was utilized. A possible mechanism of HAZ liquation cracking was suggested, on the basis of microstructure examination and thermal analysis. The HAZ liquation cracking of the diluted Inconel 625 and Inconel 718 with Nimonic 80A was closely related with solidification temperature range and the amount and distribution of γ/NbC and γ/Laves eutectic phases formed along the solidification grain boundaries. As the dilution was increased, the C/Nb ratio increased, while the amount of eutectic phases decreased. The solidification temperature range was lowered with increases in the dilution in each overlay. Therefore susceptibility of HAZ liquation cracking diminished with increases in dilution.