It was developed in collaboration between the US Air Force and the Ellwood National Forge Company.
Unlike some other high-performance alloys, Eglin steel can be welded easily, broadening the range of its application.
For toughness, the Charpy notch impact is 56.2 foot-pounds (76 J) at room temperature, and 42.7 ft-lbs (58 J) at -40F (-40°C).
By varying the heat treatment to include water or liquid nitrogen quenching, or omitting the normalization heat-treat to permit work hardening, properties can be improved.
Next the samples were austenized by repeating the process up to 1700F, and held for an hour per inch of section size, then oil quenched to below 125F.
Finally, they were tempered by in an oven that started below 500F, increased at 100F per hour per inch of section size, and allowed to air-cool to room temperature.