Hard Particle Bearing Damage

[enirwin]

I'm looking at a case hardened pump shaft that also serves as an inner race for a needle bearing. The shaft has hard particle dents all over it and is starting to spall in one spot.

How hard does a particle have to be to dent the surface of a steel shaft with a case hardness of HRC60? I have a potential source of cast iron debris at HRC20-30. Would this be hard enough to cause dents?

Any help would be appreciated.

Thanks.

 

[Carburize]

Yes - even though the case is hard if it is thin and the underlying base material is soft then indendation damage can occur quite easily even with relatively soft particles.