Precipitation hardenable stainless steel

Claim 1

A PRECIPITATION HARDENABLE STAINLESS STEEL CHARACTERIZED BY A GOOD COMBINATION OF STRENGTH AND TOUGHNESS AND CONSISTING ESSENTIALLY OF ABOUT 11.5% TO 15.5% CHROMIUM, ABOUT 9% TO AOBUT 12% NICKEL WITH THE PROVISO THAT THE SUM OF 0.8 TIMES THE CHROMIUM CONTENT PLUS THE NICKEL CONTENT IS AT LEAST ABOUT 19% AND NOT MORE THAN ABOUT 22%, AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF TITANIUM AND COLUMBIUM, THE TITANIUM BEING FROM ABOUT 0.1% TO NOT MORE THAN 0.5 AND THE COLUMBIUM BEING FROM 0.05% TO 1%, ABOUT 0.2% TO 1.6% ALUMINUM WITH THE PROVISO THAT THE SUM OF THE ALUMINUM AND ANY COPRESENT TITANIUM DOES NOT EXCEED 1.9% AND WITH THE FURTHER PROVISO THAT THE RATIO OF NICKEL TO THE SUM OF ALUMINUM AND ANY COPRESENT TIATNIUM IS AT LEAST 5 TO 1, CARBON IN AN AMOUNT UP TO 0.03%, UP TO 0.2% MANGANESE, UP TO 0.2% SILICON, UP TO 0.5% VANADIUM, UP TO 1% TANTALUM, UP TO 0.5% COPPER, UP TO 0.1% BERYLLIUM, UP TO 0.01% BORON, UP TO 0.05% ZIRCONIUM AND THE BALANCE ESSENTIALLY IRON.