Ferritic stainless steel having high temperature creep resistance

A ferritic stainless steel comprising:

• 25 up to 35 weight percent chromium;
• 0.75 to less than 1.5 weight percent molybdenum;
• up to 0.005 weight percent carbon;
• at least one of niobium, titanium, and tantalum, wherein the steel includes no more than 0.50 weight percent titanium, and the sum of the weight percentages of niobium, titanium, and tantalum satisfies the equation
• 0.5≦(%Nb+%Ti+½(%Ta))≦0.75,
• wherein the coefficient of thermal expansion of the steel is within about 25 percent of the coefficient of thermal expansion of stabilized zirconia between 20° C. (68° F.) and 1000° C. (1832° F.), and wherein the steel, exhibits at least one creep property selected from creep rupture strength of at least 1000 psi at 900° C. (1652° F.), time to 1% creep strain of at least 100 hours at 900° C. (1652° F.) under load of 1000 psi, and time to 2% creep strain of at least 200 hours at 900° C. (1652° F.) under load of 1000 psi.

A method for making a ferritic stainless steel, the steel having a coefficient of thermal expansion within about 25 percent of the coefficient of thermal expansion of stabilized zirconia between 20° C. (68° F.) and 1000° C. (1832° F.), and at least one creep property selected from creep rupture strength of at least 1000 psi at 900° C. (1652° F.), time to 1% creep strain of at least 100 hours at 900° C. (1652° F.) under load of 1000 psi, and time to 2% creep strain of at least 200 hours at 900° C. (1652° F.) under load of 1000 psi, the method comprising:

• providing a ferritic stainless steel comprising greater than 25 weight percent chromium, 0.75 to less than 1.5 weight percent molybdenum, up to 0.05 weight percent carbon, and at least one of niobium, titanium, and tantalum, wherein the steel includes no more than 0.50 weight percent titanium, and the sum of the weight percentages of niobium, titanium, and tantalum satisfies the equation
• 0.5≦(%Nb+%Ti+½(%Ta))≦1;
• and
• solution annealing the steel.