TiAl Alloy Manufacturing Using Plasma Arc Melting Technology

TiAl Alloy Manufacturing Using Plasma Arc Melting Technology Over the last several years, Plasma Melting Technology has demonstrated excellent control to produce double melt TiAl materials for low pressure turbine (LPT) blades in commercial aero engines. Other applications include turbo-charger wheels for earth moving equipment and diesel and gasoline engines. Some challenges in PAM TiAl manufacturing lies in the control of rapid solidification during casting. Because gamma alloys have very low ductility, simulation models have been used to predict internal stress of different cast shapes to prevent cracking. Ti. 48-2-2 is the most commonly used within the gamma alloy family due to its ductility and toughness needed for high temperature applications. Other gamma alloys have been produced using the PAM process, but on a more limited basis. Because of the high casting rates along with chemistry control over other casting methods such as VAR, cold wall (permanent mold) casting, Arconic has been developing the PAM TiAl casting technology and because of the success, has recently installed a full production facility capable of > 1mil lbs per year. To reduce costs, the ability to recycle the TiAl is critical. The active refining mechanisms in hearth melting along with a favorable ratio of liquid pool volume to material addition, creates a very stable process for chemistry and particle dissolution. As the demand for higher temperature, high creep resistance alloys increase to replace heavier nickel base alloys, the PAM Melting Technology coupled with further innovative enhancements will be necessary.