Posted: December 2nd, 2015

You are to determine the best material from which to fabricate a 2" diameter 5" long spiral pinion gear. The gear must have a surface hardness of 50 HRC and a core (center) hardness between 35 and 45 HRC. The alloys that you have to choose from include 1040, 4140, 4343, 5140, 8620, 8630, 8640, and 8660 steels.

You are to determine the best material from which to fabricate a 2″ diameter 5″ long spiral pinion gear. The gear must have a surface hardness of 50 HRC and a core (center) hardness between 35 and 45 HRC. The alloys that you have to choose from include 1040, 4140, 4343, 5140, 8620, 8630, 8640, and 8660 steels.

You also may use carburization and/or heat treatment to obtain the core and surface hardness requirements.

Which steel would you use and what method would you use to harden the surface of the gear?

You must show all work and justify your answer.