Patent ID: 6270594
Filing Date: 2001-08-07
Classification: C22C

Abstract:
In a method of making a rolled product by casting an alloy steel into a cast form, hot rolling the cast form into a partially rolled product, control rolling the partially rolled product into a rolled product, discontinuing control rolling at a discontinue rolling temperature, and air cooling the rolled product from the discontinue rolling temperature to ambient temperature, an improved method of making a rolled product the steps of the improved method comprising:a) providing a cast form having a thickness (t.sub.1) and an alloy steel composition consisting essentially of, in weight percent:less than 0.04% silicon;between 1.00 and 2.00% manganese;between 0.006 and 0.020% titanium;up to 0.012% nitrogen;between about 0.005 and 0.080% aluminum;between about 0.05 and 0.10% vanadium;between about 0.01 and 0.05% niobium; andbetween about 0.06 and 0.14% carbon;the balance iron and incidental impurities;b) hot rolling said cast form within a first rolling temperature range and reducing said cast form to a partially rolled product having a thickness (t.sub.2);c) control rolling said partially rolled product form in a second rolling temperature range and reducing said thickness t.sub.2 to make a rolled product having a thickness (t.sub.4), the control rolling to thickness t.sub.4 being finished at a finish rolling temperature ranging between about 1490.degree. F. to about 1675.degree. F.; andd) accelerated cooling said rolled product having said thickness t.sub.4 to a finish cooling temperature (FCT),e) wherein the rolled product has a yield strength of at least 65 ksi and a tensile strength of at least 80 ksi.