Martensitic steel

Claim 1

A CONTINUOUS PROCESS FOR MAKING THIN GAUGE HIGH TENSILE STRNGTH STEEL SHEET OR STRIP WHICH COMPRISES PASSING THROUGH A HEATING ZONE A CONTINUOUS SHEET OR STRIP OF PLAIN CARBON THIN GAUGE STEEL IN WORK HARDENENED STATE AND HAVING A CARBON CONTENT OF FROM ABOUT .03 WT. PERCENT TO ABOUT .25 WT. PERCENT, A MANGANESE CONTENT OF FROM ABOUT .20 WT. PERCENT TO ABOUT .60 WT. PERCENT, AND A THICKNESS OF FROM ABOUT 9002 TO ABOUT .100 INCH, AND THEREIN HEATING THE SHEET OR STRIP TO A TEMPERATURE ABOVE THE A3 CRITICAL SO AS TO AUSTENITIZE THE STEEL, SAID WORK HARDENED SHEET OR STRIP BEING OBTAINED BY COLD REDUCTION BY AT LEASTA ABOUT 40% OF AN INTERMEDIATE GAUGE MATERIAL AND SAID WORK HARDENED SHEET OR STRIP BEING CHARACTERIZED BY A TENSILE STRENGTH ON THE ORDER OF ABOUT 100,000 P.S.I. AND AN ELONGATION IN TWO INCHES OF LESS THAN ABOUT 1%, AND IMMEDIATELY THEREAFTER PASSING THE SHEET OF STRIP THROUGH A QUENCH ZONE AND THEREIN UNIFORMLY QUENCHING THE AUSTENIZED STEEL SHEET OR STRIP TO OBTAIN A PRODUCT HAVING A MICROSTRUCTURE CONSISTING ESSENTIALLY OF TAMPERED MARTENSITE, A TENSILE STRENGTH OF AT LEAST ABOUT 130,000 P.S.I., AND AN ELONGATION IN TWO INCHES OF AT LEAST ABOUT 1.5%.