Duplex stainless steel

A duplex stainless steel consisting essentially of, in weight percent:

• up to 0.06 percent carbon;
• 15 up to 22.5 percent chromium;
• greater than 3 up to less than 4 percent nickel;
• up to 3.75 percent manganese;
• 0.14 up to 0.35 percent nitrogen;
• up to 2 percent silicon;
• greater than 1.4 up to less than 2.5 percent molybdenum;
• up to less than 0.5 percent copper;
• up to less than 0.2 percent cobalt;
• up to 0.05 percent phosphorous;
• up to 0.005 percent sulfur;
• 0.001 up to 0.0035 percent boron;
• iron and incidental impurities.

A duplex stainless steel comprising, in weight percent:

• up to 0.03 percent carbon;
• 15 up to less than 21 percent chromium;
• greater than 3 up to less than 4 percent nickel;
• up to 2 percent manganese;
• 0.14 up to 0.20 percent nitrogen;
• up to 1 percent silicon;
• 1.5 up to 2 percent molybdenum;
• less than 0.4 percent copper;
• less than 0.2 percent cobalt;
• up to 0.03 percent phosphorous;
• 0.001 up to 0.0035 percent boron;
• iron and incidental impurities.

A method for making a duplex stainless steel, the process comprising:

• providing a duplex stainless steel alloy comprising, in weight percent, up to 0.06 percent carbon, 15 up to 22.5 percent chromium, greater than 3 up to less than 4 percent nickel, up to 3.75 percent manganese, 0.14 up to 0.35 percent nitrogen, up to 2 percent silicon, greater than 1.4 up to less than 2.5 percent molybdenum, up to less than 0.5 percent copper, up to less than 0.2 percent cobalt, up to 0.05 percent phosphorous, up to 0.005 percent sulfur, 0.001 up to 0.0035 percent boron;
• iron and incidental impurities;
• solution annealing the steel;
• and
• cooling the steel.