Alternative to Nitrided 20MnCr5

I’ve been assigned to a project of a spindle where I need to find a replacer to nitrided 20MnCr5.

The current process:
Pre machining of the spindle; quenching and tempering to obtain 25~29 HRc; final machining; surface nitriding (0,3mm) to obtain >650Hv; griding.

My question is if you think AISI 4140 with induction surface hardening could be a alternative to the current process, since we have it with 25~30 HRc, and under hardening conditions ranges from 55 to 60 HRc.


We have made conversions from a carburized to an induction hardened process using similar materials. You may need to validate the change with some type of fatigue testing based on the expected loading your spindle will see in service.

Above is a snippet.

20MnCr5 is a case carburizing steel similar in chemical composition to SAE 5120. There are a large number of case carburizing steel alloys available in the United States that are superior in hardening response, toughness, fatigue, etc. Can you provide a drawing for the component in question, and identify the area(s) requiring elevated hardness? Why are you nitriding instead of case carburizing? Has distortion been a problem in the past on this component?

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Sorry Maui, there were no images of the component in the cited thread.