| Abstract |
| The effect of the heat treatment condition to introduce the grain boundary (GB) serration on the creep properties was investigated at 950 ℃ in a solid-solution-strengthened Alloy 617. Serrated GBs without carbide at the early stage of slow-cooling were newly observed, and appear to challenge previous models. As the aging temperature for which the specimen was slow-cooled from 1200 ℃ decreased, the amplitude and the fraction of the serration became higher. The serrated GBs with stable planar M23C6 carbides caused a fairly long period of a steady-state stage due to their higher resistance to GB cavitation cracking as well as substantial suppression of recrystallization. The very fine and stable intragranular carbides, which precipitated uniformly throughout the serrated specimen aged at 1000 ℃ during the initial stage of creep, were responsible for the further improvement in the creep rupture life (up to 2.8 times longer) by lowering the creep strain rate. |
|
|
| Key Words |
| alloys, allogs, aging, creep, transmission electron microscopy, TEM, grain boundary serration |
|
|
 |
|
