NEW DEVELOPMENTS IN WROUGHT 718-TYPE SUPERALLOYS

Research and development efforts are still very active on 718-type alloys although two major members of this widely used family, 718 and 625, were invented almost a half-century ago. Emphasis in this type of work at ATI Allvac is directed at improving existing alloys and developing new alloys to meet ever-increasing industrial demands. The improvement of existing alloys is exemplified by addition of minor elements P and B in alloy 718. The discovery of the beneficial effect of P and B in wrought alloy 718 led to development of a new, modified alloy, AllvacH 718 ERR. A large effort has also been directed at studying the effects of major element modifications in 718-type alloys, and a new alloy, AllvacR 718PlusTM, has been developed. The new alloy has much better high temperature capability, especially thermal stability, approaching the level of Waspaloy but retains excellent processing characteristics, similar to alloy 718. Alloy 718PlusTM should be useful in any 718-type application requiring a higher working temperature. The properties and processing of this alloy are introduced in this paper.