high strength, high toughness alloy steel with good tempering resistance and hardened and tempered alloy article

摘要

A high strength, high toughness steel alloy is disclosed. The alloy has the following broad weight percent composition. Element Broad C 0.35-0.55 Mn 0.6-1.2 Si 0.9-2.5 P 0.01 max. S 0.001 max. Cr 0.75-2.0 Ni 3.5-7.0 Mo + ½ W 0.4-1.3 Cu 0.5-0.6 Co 0.01 max. V + ( 5/9) x Nb 0.2-1.0 Fe Balance Included in the balance are the usual impurities found in commercial grades of steel alloys produced for similar use and properties. Also disclosed is a hardened and tempered article that has very high strength and fracture toughness. The article is formed from the alloy having the broad weight percent composition set forth above. The alloy article according to this aspect of the invention is further characterized by being tempered at a temperature of about 500° F. to 600° F.