Yes, it is possible to obtain Type 420 stainless steel that is quenched and tempered to a range of 50-60 HRC. Probably ~ 57 HRC is the maximum, but certainly > 46-48 HRC is possible with this alloy.
Does anyone have any information reference induction hardening and what you can do to ioncrease final hardness?
(ie quench at sub zero effects of this etc...)
1.To maximize hardness you need to make sure you get all the carbon dissolved during austenitizing. With your rapid heating via induction you may just be transforming to austenite and not getting full solution treatment.
2.There may be some retained austenite after quench which would require sub-zero treatment to transform and give you your final couple of points of hardness.
3. the carbon level of the alloy will have to be at the high end of the range to get the greatest possible hardness.