Abstract: A solid solution, nonmagnetic, austenitic nickel base alloy class is described. It contains: about 12 to 21 weight percent chromium; a concentration of molybdenum and/or tungsten, such that the sum of the weight percent molybdenum and one third the weight percent tungsten present is between 1 and 7 weight percent and wherein the w % tungsten is less than 12 w %; about 4 to 13 w % iron; small but effective amounts of the desulfurizing agent, manganese; and up to about 2.5 w % silicon. Carbon may be present at levels up to 0.15 w % and cobalt may be present at levels up to 2 w %. The above elements are balanced to provide alloys having a mean thermal expansion coefficient, .alpha..sub.(RT-T), for T.ltoreq.1000.degree. F., of less than 8.3.times.10.sup.-6 in./in./.degree.F., and preferably less than 8.times.10.sup.-6 in./in./.degree.F.In addition, a precipitation hardening, non-magnetic, austenitic nickel base alloy class is also described.

Abstract: Duplex stainless steel materials containing austenite plus delta ferrite, are dimensionally stabilized by heating the material to a reaction temperature between about 1050.degree.-1450.degree. F. (566.degree.-788.degree. C.), holding it at this temperature during transformation of delta ferrite to austenite plus sigma phase, and subsequently heating to a reversion temperature between about 1625.degree.-1750.degree. F. (885.degree.-954.degree. C.), whereby the sigma phase transforms back to ferrite, but the austenite remains dispersed in the ferrite phase. Final controlled cooling permits transformation of ferrite to austenite plus sigma and, later, precipitation of carbides.

Abstract: A cold-worked, high strength, non-magnetic, austenitic, ferrous alloy having high resistance to stress-corrosion cracking and hydrogen embrittlement. Composition of this alloy in weight percent is:______________________________________ Manganese 17 to 23 Chromium >6 to <10 Carbon 0.35 to 0.8 Silicon up to 1.5 Nickel up to 2.75 Molybdenum up to 3.5 Vanadium up to 1.7 Columbium up to 0.45 Nitrogen up to 0.8 Iron Balance ______________________________________With carbon plus nitrogen 0.35 to 0.8 and the manganese plus chromium between 24 and 31.5. Also a large electrical generator with retaining and baffle rings of the alloy. Also a method of hardening this alloy by cold working and aging.