Payne, Shirley and McIntyre, P.
Influence of grain boundary microstructure on the susceptibility of Inconel 600 to intergranular attack and stress corrosion cracking.
The influence of grain boundary microstructure on the susceptibility of thermally treated (TT) Inconel Alloy 600 to intergranular attack (IGA) and stress corrosion cracking (SCC) in 30%NaOH plus 10% Na2SO4 at 350ºC was investigated. Both mill-annealed (MA) and laboratory solution-annealed alloys were aged at 700 C to establish the effect of intitial processing on the response to thermal treatment. Treatments of 1 h or more at 700ºC improved the SCC resistance of solution-annealed material but did not improve the performance of MA material containing a high density of intraganular carbides. The poor behavior after thermal treatment is associated with the formation of small M23C6 carbides growing at a high angle to the boundaries and the development into cellular colonies. This is attributed to the use of a MA temperature that was too low to take into solution sufficient carbon for the development of semicontinuous grain boundary carbides during the subsequent TT process.
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