Message posted by Peter Merlin (Member since 11/13/2003) on October 14, 2023 at 18:06:49 PST:
The J58 engines were built from a variety of materials capable of withstanding extreme pressures and temperatures. The forward compressor stages and inlet case were made of titanium alloys, including Ti-8-1-1 and Ti-5-2.5, because those alloys have good creep properties at temperatures up to 850˚F. The first-stage turbine vanes incorporated Mar-M-20ODS, a nickel-base alloy that was cast with spanwise columnar crystal grains. Its granular structure reduced the risk of thermal shock cracking. Some first and second stage turbine blades, second-stage turbine vanes, and afterburner nozzle flaps were made from IN-100, another nickel-base alloy. The diffuser case was constructed using Inconel-718 nickel alloy, capable of withstanding 1,250˚F. Most J58 engine components were made of Waspaloy, an oxidation-resistant nickel-base alloy capable of withstanding 1,400˚F. Burner components were made of Hastelloy-X. Turbine disks were made of Astroloy, a precipitation-hardened nickel-base alloy suitable for operations up to 1,500˚F. This extremely expensive material was available as a forging, and had creep and tensile strength qualities superior to Waspaloy. Parts with similar applications to Hastelloy-X, but requiring greater resistance to buckling and sliding wear, were made of L-605 (Haynes 25). A cobalt-base alloy, L-605 was easy to weld and form. This alloy was later replaced by Haynes 188 and Haynes 230 which had improved oxidation resistance.
In Reply to: Re: SR-71 turbojet and ramjet engines posted by Vahe Demirjian on October 14, 2023 at 17:56:20 PST:
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