New and improved alloys have been developed to improve turbine engine capability and/or reduce overall casting cost.
CM 939 Weldable 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 parent alloy 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 Alvac as a wrought disc alloy with improved operating temperature capabilities over standard IN 718 (+100 F). In collaboration and under license from ATI alvac, Honeywell and Cannon-Muskegon are developing a cast version with good castability-no cracking and good structural weld repairability-no heat affected zone (HAZ) microcracking. This is a new design area for structural castings in new engine applications.
These recent advances in alloy development have focused on reducing alloy and component cost and improving quality. 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.