Patent ID: 8414713
Filing Date: 2013-04-09
Classification: C21D,C22C

Abstract:
1. A high hardness, high strength and high impact toughness steel for armor plates, deep penetrating bombs and missiles comprising by % weight of about 0.3% to 0.45% of C, about 1.0% to 3.0% of Cr, about 0.1% to 0.55% of Mo, about 0.1% to 2.0% of W, about 0.1% to less than 3.0% of Ni, about 0.1% to 1.0% of Mn, about more than 0.3% to 1.0% of about 0.1% to 0.6% of Cu, about 0.02% to 0.2% of Ti or Nb, about more than 0.1% to 0.55% of V and a balance of Fe and incidental impurities, said steel having a dispersed tempered martensite microstructure comprised of packets of martensitic lathes, titanium carbides as centers of growth of said martensitic lathes, and retained austenite with boundaries of said packets free of carbides, said steel having a hardness of Rockwell C 54 to 56, an ultimate tensile strength of about 290 ksi to 305 ksi, a yield strength of about 225 ksi to 235 ksi, an elongation of about 13% to 14%, a reduction of area of about 47% to 50%, and a Charpy V-notch impact toughness energy of about 26 ft-lb to 28 ft-lb at room temperature.