There is a need for metallic materials that have useful strengths at temperatures in excess of 1090.degree. C. (1994.degree. F.). In ordinary usage, metallic materials operating at such temperatures are exposed to the deleterious effects of oxidation and sulfidation corrosion often in the presence of molten slag-like materials, for example molten silicate based slags and molten glass. In order to be practical, metallic materials operable at such temperatures must be hot workable so as to economically provide the shaped objects which are to be used.
U.S. Pat. No. 4,877,435, incorporated by reference, discloses a mechanically alloyed (MA) material with an approximate composition of 30-40% chromium, 5-25% cobalt, 0.5-10% iron, 0.2-0.6% aluminum, 0.3-1.2% titanium, 0.2-1% yttria and the balance nickel. Manganese may be present up to 2%, boron may be present to 0.05%, zirconium up to 0.4% and others (silicon, niobium, tantalum, molybdenum, tungsten, rhenium, hafnium, lanthanides and yttrium) up to about 1%. The consolidated and hot worked alloy has exceptional hot corrosion resistance and, when grain coarsened, good high (1093.degree. C. [1994.degree. F.]) temperature strength. Such an alloy is useful for the handling of molten glass.
Whereas this material can be hot formed to a plate product by conventional hot rolling, fabrication of molten glass spinners by hot spinning has been unsuccessful due to surface cracking and, in one instance, catastrophic brittle fracture. U.S. Pat. No. 4,877,435 states the alloy has excellent hot ductility if several conditions are met: (1) the carbon level is under 0.08% to minimize carbide precipitation, (2) the oxygen level should be less than 0.5% and best ductility is achieved when the oxygen is under 0.40%, (3) the weight percent titanium should be four times the weight percent nitrogen to insure the formation of innocuous titanium nitrides, and (4) the combined oxygen plus nitrogen level should be under 0.7%. Satisfying these conditions insures that the alloy has a 954.degree. C. (1750.degree. F.) high temperature tensile ductility over 40% which is an indicator of acceptable hot ductility. It is true that when these conditions are satisfied, the alloy does have a 954.degree. C. tensile ductility over 40%. However, this does not translate into adequate hot ductility for the spin forming operations.