PHYSICAL METALLURGY OF ALLOYS 718, 725, 725HS, 925 FOR SERVICE INAGGRESSIVE CORROSIVE ENVIRONMENTS

摘要

Processing conditions were designed to produce alloys 718 (UNS N07718), 725 / 725HS (UNSrnN07725), and 925 (UNS N09925) with essentially clean grain boundaries, partial coverage of grainrnboundaries by the precipitates, and full coverage of grain boundaries by the precipitates. Grain boundaryrnprecipitates were found to degrade room temperature impact strength. Partial coverage of grainrnboundaries by second phase particles did not adversely affect the properties in slow strain rate (SSR)rntests conducted in the oil patch environments. However, the materials having grain boundaries fullyrncovered with second phase particles had inferior properties in SSR testing.