Abstract: A process for making a precipitation hardenable stainless steel alloy is described. The process includes the step of melting a martensitic steel alloy having the following composition in weight percent, about Carbon ?0.03 max. Manganese ?1.0 max. Silicon ?0.75 max. Phosphorus 0.040 max. Sulfur 0.020 max. Chromium 10-13 Nickel 10.5-11.6 Titanium 1.5-1.8 Molybdenum 0.25-1.5? Copper ?0.95 max. Aluminum ?0.25 max. Niobium ?0.3 max. Boron 0.010 max. Nitrogen 0.030 max. and the balance being iron and usual impurities. The process also includes the step of adding calcium to the alloy while molten. The calcium combines with available sulfur and oxygen to form calcium base inclusions selected from the group consisting of calcium sulfides, calcium oxides, calcium oxysulfides, and combinations thereof. In a further step, the alloy is processed to remove at least a portion of the calcium base inclusions. The alloy is then solidified.

Abstract: A process for making a precipitation hardenable stainless steel alloy is described. The process includes the step of melting a martensitic steel alloy having the following composition in weight percent, about Carbon 0.03 max. Manganese 1.0 max. Silicon 0.75 max. Phosphorus 0.040 max. Sulfur 0.020 max. Chromium 10-13 Nickel 10.5-11.6 Titanium 1.5-1.8 Molybdenum 0.25-1.5? Copper 0.95 max. Aluminum 0.25 max. Niobium 0.3 max. Boron 0.010 max. Nitrogen 0.030 max. and the balance being iron and usual impurities. The process also includes the step of adding calcium to the alloy while molten. The calcium combines with available sulfur and oxygen to form calcium base inclusions selected from the group consisting of calcium sulfides, calcium oxides, calcium oxysulfides, and combinations thereof. In a further step, the alloy is processed to remove at least a portion of the calcium base inclusions. The alloy is then solidified.

Abstract: An age hardenable, martensitic steel alloy that provides high strength, high toughness, and good low cycle fatigue life and a method of making same are disclosed. The alloy comprises a matrix having a weight percent composition consisting essentially of about Carbon ?0.2-0.36 Manganese 0.20 max. Silicon 0.10 max. Phosphorus 0.01 max. Sulfur 0.004 max. Chromium ?1.3-4 Nickel ??10-15 Molybdenum 0.75-2.7 Cobalt ??8-22 Aluminum 0.01 max. Titanium 0.02 max. Calcium 0.001 max. and the balance being iron and usual impurities. The alloy further contains a plurality of inclusions dispersed in the alloy matrix. The inclusions comprise calcium compounds that are about 0.4 ?m to about 7.0 ?m in major dimension, they have a median size of at least about 1.6 ?m in major dimension, and the inclusions contain essentially no rare earth elements.