Nitriding Leaded Steels

[curvyrace]

Does anyone know if there are significant differences in nitriding 4100 series steels versus leaded 4100 series steels? The part in question carries a low load, so core hardness and strength are not issues. The main concerns are case hardness and depth, as well as a high degree of machineability. Thanks!

 

[unclesyd]

There is a decided machining advantage with AISI 41L40 vs AISI 4140. Over the years we made components from 41L40 that had to be nitrided for wear.
One component we made was a texturizing gear 2 1/2" dia x 3" wide. The teeth were machined tear dropped shaped on a Fellows Gear Shaper. The parts were machined in the annealed state and then heat treated followed by gas nitriding.

Without the Lead the part would have been prohibitively expensive to machine due to the intricacy of the cutter for the Fellows Shaper.

The process wasn't without problems as we lost a couple of percent in machining due to tears from elongated lead stringers. We also loss few in the heat treating and nitriding process again due to lead stringers.

Leaded 4100 series steels aren't the panacea for all machining problems. It is back to the risks versus rewards for a particular item. A case in point is that we made numerous parts from 4140 that underwent numerous thermal and pressure cycles where 41L40 would have a very short life.

If you have a particular problem in mind you should comeback with it and get some other responses.