Weld Mold 4637 description: 4637 is a nickel-based chromium, molybdenum, cobalt alloy commonly known as Waspaloy. Because of its excellent high temperature (up to about 1800F) and high stress performance Waspaloy is widely used as a wrought material for forged and fabricated gas turbine components. For the same reasons it is gaining popularity as a composite material in the forging industry where it has proven its ability to prolong forging die life.