Methods and compositions for improved low alloy high nitrogen steels

A method of making a low alloy high nitrogen steel structure, the method comprising:

• forming a steel composition using nitrogen additive constituents and under a first gas atmosphere of 1 bar to 40 bars pressure or more, wherein said first gas atmosphere comprises any of inert argon, nitrogen, or a controlled atmosphere conveying nitrogen, and wherein said steel composition comprising iron and, by weight:
• 0.16-0.60% nitrogen (N),
• 0.03-0.20% carbon (C),
• 0.10-2.00% nickel (Ni),
• 0.60-2.00% manganese (Mn),
• 1.30-2.80% chromium (Cr),
• 0.60-1.50% molybdenum (Mo),
• not more than 0.05% tungsten (W),
• not more than 0.02% vanadium (V),
• not more than 0.60% silicon (Si),
• not more than 0.10% copper (Cu),
• not more than 0.02% titanium (Ti),
• not more than 0.02% niobium (Nb),
• not more than 0.008% aluminum (Al), and
• not more than 0.02% of any other element with not more than 0.10% total other elements,
• wherein cobalt (Co) is substitutable for any part of the nickel;
• casting liquid to solid or solid state processing under a first atmosphere to said steel composition or shape;
• hot working or forming said steel composition to a shape;
• heating said steel composition to first normalize and cool, then to austenitize;
• quenching said steel composition at a rate to produce substantially a martensitic microstructure;
• and
• heating tempering said steel composition under vacuum or a second gas atmosphere, wherein said second gas atmosphere comprises air, controlled atmosphere with any of ammonia, hydrogen, inert nitrogen, or nitrogen and argon.