 Held at 1750F for an hour per inch of section size, and then air-cooled to room temperature.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.