Advances in Cast Superalloy Technology for Improved Capability and Reduced Cost

摘要

New and improved alloys have been developed to improve turbine engine capability and/or reduce overall casting cost. CM 939 Weldable? alloy was developed to be a castable and structurally weld repairable version of IN 939, which has extensive application in industrial gas turbine engines. Along with excellent creep properties at increased temperatures (1475?F for structural parts), this alloy can be weld repaired using the various alloys for filler metal. This ability reduces the amount of scrapped parts a foundry has to discard after getting through many expensive processing steps. 718Plus? alloy was developed by ATI Allvac? as a wrought disc alloy with improved operating temperature capabilities over standard IN 718 (+100?F). In collaboration and under license from ATI Allvac, Honeywell and Cannon-Muskegon are developing a cast version with good castability - no cracking and good structural weld reparability - no HAZ microcracking. This is a new design area for structural castings in new or existing engine applications. CMSX?-8 alloy optimizes alloying elements for a new generation of single crystal (SX) superalloys. This alloy reduces the amount of rhenium, an expensive element used in second and third generation SX alloys, while maintaining comparable properties to second generation superalloys (CMSX-4?, René N5) up to 1950?F. These recent advances in alloy development have focused on reducing alloy and component cost, while improving quality and capability. This has been done through lowering the cost to manufacture the alloy, enhanced temperature capabilities, reduced alloy cost, and improved castability. Improved quality is achieved through controlling trace and tramp elements through comprehensive and optimized raw material selection, vacuum induction melting/refining technology, and process control.