Direct verification of hardness Bri

[LEB1]

Direct verification of hardness Brinell Machines.
During a recent Audit it was brought up that the direct verification for the brinell machine wass only verified to BS EN ISO 6506-2. We do not hold a verification report for ASTM E10. can anyone advise if this is required or is there a clause in ASTM which allows the DIRECT verification of the BS EN ISO 6506 to be used.
ALSO what constitutes a "surface hardness" when checking surfaces with decarb on? if we have a decarb surface is there a "safe" area where we can take the brinell to ensure we are through the decard layer or do we have to check the decarddepth first.

thanks in advance.
L.E.B.1

 

[redpicker]

can anyone advise if this is required or is there a clause in ASTM which allows the DIRECT verification of the BS EN ISO 6506 to be used.

I really am not well versed in the requirements of ISO 6506, but it does seem to be functionally equivalent to ASTM E10, so if the direct verification requirements of ISO 6506 meet the direct verification requirements of ASTM E10, I would say the certification to ISO 6506 would also be valid for ASTM E10. It might help if you got your QA manual changed to reflect this, if this is in fact, correct.

ALSO what constitutes a "surface hardness" when checking surfaces with decarb on? if we have a decarb surface is there a "safe" area where we can take the Brinell to ensure we are through the decarb layer or do we have to check the decarb depth first.

"Surface Hardness" is just that, the hardness of the surface. The product specification should have allowance for removal of surface decarburization, if that is required to obtain an accurate hardness. However, not all product specifications are created equal in this respect. I have seen some product specification state a specific depth to be removed prior to hardness check, others that only state that the decarb layer is to be removed, and still others that make no mention of the decarb layer, but it is obvious that the implication is that decarb layer must be removed prior to checking for hardness. The depth of the decarb layer depends on the processing methods and, without knowing your situation, I cannot comment on that. In general, between 1/16" to 1/8" is adequate for forgings from my experience, but other products, or even specific forging processes, may produce a shallower or deeper layer. Generally, I would recommend something like 1/16" and evaluate the result. If I had any questions, I'd go deep enough to remove the impression, and re-check. If the two results were the same, I'd figure it was a representative result and use that depth for other items with the same processing. If there was a difference, I think I'd keep going deeper until I got a consistent value.

rp