Articles made of nickel-based superalloys with improved machinability, as well as a process for the preparation of a machined workpiece from such a superalloy

摘要

Provided is a cast nickel-base superalloy having improved machinability characteristics having a formulation by weight percent of: upto 0.017 carbon, 0 - 0.015 phosphorus, 0 - 0.015 sulfur 17.00 - 21.00 chromium, 50.00 - 55.00 nickel, 2.80 - 3.30 molybdenum, 4.40 - 5.50 niobium and tantalum combined, 0.30 - 0.80 aluminum, 0.65 - 1.15 titanium, 0 - 0.006 boron, 0 - 0.35 manganese, 0 - 1.00 cobalt, 0 - 0.35 silicon, 0 - 0.30 copper, and the balance iron. The cast article may be hot-isostatically pressed at a temperature and pressure sufficient to substantially reduce segregation within the nickel-base superalloy, and thereafter heat-treated to achieve a fill precipitation heat-treated condition, which substantially increases the strength of the superalloy. Subsequent to hot-isostatic pressing and heat-treatment, the cast article has a standard machinability rating of at least 13% when compared to an AMS5010 steel.