Low alloy steel containing boron and titanium for high-temperature use

Claim 1

A HOT WORKED AND HEAT TREATED STEEL ARTICLE FOR OPERATION AT ELEVATED TEMPERATURES UP TO AT LEAST 1100* F., THE ARTICLE HAVING BEEN NORMALIZED FROM ABOUT 1800* F. AND TEMPERED AT ABOUT 1200* F. TO 311 TO 321 BRINELL AND HAVING ROOM TEMPERATURE TENSILE STRENGTH OF ABOUT 150,000 POUNDS PER SQUARE INCH, A RUPTURE STRENGTH IN 1000 HOURS AT 1100* F. OF AT LEAST ABOUT 40,000 POUNDS PER SQUARE INCH AND ELONGATION AT RUPTURE OF ABOUT 21 PER CENT, AND HAVING SUBSTANTIALLY THE FOLLOWING COMPOSITION: CARBON 0.15 TO 0.5 PER CENT, BORON 0.0005 TO 0.004 PER CENT, CHROMIUM 0.75 TO 2.5 PER CENT, MANGANESE 0.2 TO 2 PER CENT, MOLYBDENUM 0.25 TO 1 PER CENT, SILICON 0.1 TO 1.5 PER CENT, VANADIUM 0.2 TO 1 PER CENT, AND TITANIUM FROM 1 TO 6 TIMES THE AMOUNT OF CARBON, AND THE REMAINDER IRON TOGETHER WITH IMPURITIES AND ELEMENTS IN A TOTAL AMOUNT THAT DOES NOT IMPAIR THE STATED PROPERTIES.