Microstructure and Hydrogen-Induced Failure Mechanisms in Fe and Ni Alloy Weldments |
| |
Authors: | J A Fenske I M Robertson Raghavan Ayer Martin Hukle Dan Lillig Brian Newbury |
| |
Affiliation: | 1. Department of Materials Science and Engineering, University of Illinois, Urbana, IL, 61801, USA 2. ExxonMobil Development Company, Houston, TX, 77060, USA 3. National Science Foundation, Arlington, VA, 22230, USA 4. Corporate Strategic Research, ExxonMobil Research and Engineering Company, Annandale, NJ, 08801, USA 5. Trendsetter Engineering, Inc., Houston, TX, 77070, USA 6. ExxonMobil Canada Energy, Calgary, AB, T2P 3M9, Canada
|
| |
Abstract: | The microstructure and fracture morphology of AISI 8630-IN625 and ASTM A182-F22-IN625 dissimilar metal weld interfaces were compared and contrasted as a function of postweld heat treatment (PWHT) duration. For both systems, the microstructure along the weld interface consisted of a coarse grain heat-affected zone in the Fe-base metal followed by discontinuous martensitic partially mixed zones and a continuous partially mixed zone on the Ni side of the fusion line. Within the partially mixed zone on the Ni side, there exists a 200-nm-wide transition zone within a 20-??m-wide planar solidification region followed by a cellular dendritic region with Nb-Mo?Crich carbides decorating the dendrite boundaries. Although there were differences in the volume of the partially mixed zones, the major difference in the metal weld interfaces was the presence of M7C3 precipitates in the planar solidification region, which had formed in AISI 8630-IN625 but not in ASTM A182-F22-IN625. These precipitates make the weldment more susceptible to hydrogen embrittlement and provide a low energy fracture path between the discontinuous partially mixed zones. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|