Checking Hardening Results; Corrosion Protection - Mercedes-Benz 603 Service Manual

Checking hardening results

To achieve perfect hardening check adjustment
of hardening equipment using microsections.
These can be obtained from scrapped
crankshafts hardened for testing purposes.
Check hardening by etching the journal surface
with a 2% solution of alcoholic nitric acid
Dark spots should not appear on the journal
surface.
Unhardened fillets will become dark.
In the case of hardened fillets they should
appear as bright as the surface of the journals.
We recommend comparing the etching test with
a journal tested via metallographic microsection.
Then carefully wash off nitric acid with alcohol.

Corrosion protection

Crankshafts which are not installed again
immediately should be lubricated with engine
break-in oil (SAE 30).
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