Design a process to produce a 0.5 cm-diameter steel shaft having excellent toughness, yet excellent wear and fatigue resistance. The surface hardness should be at least HRC 60, and the hardness 0.01 cm beneath the surface should be approximately HRC 50. Describe the process, including details of the heat-treat atmosphere, the composition of the steel, temperatures, and times. Present your solution as a clearly ordered sequence of steps.