I am designing a component (Cam Driver) that has 2 features. One feature that acts as a cam, it slides against another component with heavy surface stress to move the other component. The 2nd feature of this Cam Driver is a threaded rod that mates with a piston in a pneumatic cylinder, thus it is cyclically loaded as the pneumatic cylinder slams up and down. So for the cam, we want a hard wear resistant tool steel (Like D3). But for the piston rod, we want a tougher tool steel (Like L6). We made a prototype from A2 hardened to 55Rc (For legacy reasons, it was similar to some other components we have some experience with). We broke the piston rod portion in the threaded region. My ideas were: 1) Case harden this component. Is this expensive? Which steel to use? 2) Make with L6 hardened to 55Rc then anneal just the threaded piston rod portion. Is this possible? 3) Redesign to make 2 different components. Any other ideas? Any tool steels that are significantly tougher than A2 hardened to 55RC but provide nearly as good wear resistance? Thanks for any of your thoughts or ideas.