Interpret German HT requirements 1

[Tagger]

I have a German drawing calling out a heat treament requirement. I think it is based on the Vickers scale. It is a large centering ring for a hub that helps keep a shaft centered while in the hub and the ID of the ring is hardened to resist wear.
The drawing has 740 #40HV then beneath that it says Eht 2 +0.5
Is that case depth of 2mm to 2.5mm? Is that a Vickers of 740 using a 40 kg weight to determine hardness?
In German it says: "vorgedreht zurn Aufkohlen und Härten einsatzgehärtet und angelassen" showing an area outlined.

Another line says "geschützt vor Aufkohlung" showing an area outlined. I am guessing it means protect from carburizing.

Thanks for the help.

 

[CoryPad]

Yes, you need 740 HV to a depth of 2.0 to 2.5 mm. I suppose the 40 is 40 kg, but it isn't written correctly.

Vorgedreht means rough turned. Zurn is not correct - it is zum. Aufkohlen means carburized, h[ä]rten means hardening, and angelassen means tempered. I think this means to rough turn the part up to the region that has been carburized, hardened, and tempered.

Yes, the second clause means protect from carburization.



Regards,

Cory

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