Patent ID: 8636856
Filing Date: 2014-01-28
Classification: C21D,C22C,Y10T

Abstract:
1. A method of making a steel tube, comprising: providing a carbon steel composition comprising: forming the steel composition into a tube; heating the formed steel tube in a heating operation to a first temperature of about 880° C. to about 950° C. for about 10 to 30 minutes; quenching the formed steel tube in a quenching operation from the first temperature at a first rate such that the microstructure of the quenched steel is greater than or equal to about 95% martensite by volume; and tempering the formed steel tube after the quenching operation by heating the formed steel tube to a second temperature less than about 550° C.; wherein the steel tube after tempering has a yield strength greater than about 165 ksi and wherein the Charpy V-notch energy is greater or equal to about 80 J/cm