The Potential of HAZ Property Improvement through Control of Grain Boundary Character in a Wrought Ni-Based Superalloy

Abstract:

The effects of grain boundary serration on grain coarsening and liquation behavior in simulated weld heat-affected-zone (HAZ) of a wrought Ni-based superalloy Alloy 263 have been investigated. Recently, the present authors have found that grain boundary serration occurs in the absence of adjacent coarse γ' particles or M23C6 carbides when a specimen is direct-aged with a combination of slow cooling from solution treatment temperature to aging temperature. This serration leads to a change in grain boundary character as special boundary based on the crystallographic analysis demonstrating that the grain boundaries tend to serrate to have specific segments approaching to one {111} low-index plane at a boundary. The present study was initiated to investigate the interdependence of the serration and HAZ property with a consideration of this serration as a potential for the use of a damage-tolerant microstructure. It was found that the serrated grain boundaries suppress effectively grain coarsening, and are highly resistant to liquation cracking in HAZ due to their lower tendency to be wetted and penetrated by the liquid phase. These results reflect closely a significant decrease in interfacial energy as well as grain boundary configuration by the serration.

• Periodical: Materials Science Forum (Volumes 654-656)
• Pages: 488-491
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.654-656.488
• Online since: June 2010
• Authors: Hyun Uk Hong, In Soo Kim, Baig Gyu Choi, Hi Won Jeong, Seong Moon Seo, Young Soo Yoo, Chang Yong Jo
• Keywords: Grain Boundary Serration, Heat Affected Zone (HAZ), Heat Treatment, Liquation, Superalloy

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