8620 gear steel is a low carbon nickel chromium molybdenum alloy steel. And it is a low cost steel with good carburized properties. The nickel content contributes to case toughness at high strength with above average core toughness. The chromium and molybdenum support the proper formation of carbides resulting in good surface hardness and wear. 

It is used to make a wide range of gears, crankshafts, gear rings, pinions, piston pins, cams, gauges, tie bars, collets, bushings and bolting as well as hand tools and a multitude of machinery parts and components. Structural parts such as gears, pinions, spline shafts, pins and a variety of other important applications requiring a hard wear surface and a ductile core.