Posted by Gordon England on May 09, 2003 at 02:54:37:
In Reply to: Rockwell Vs. UTS posted by Michael Doyle on May 08, 2003 at 19:36:06:
: I have a dispute regarding Rockwell and ultimate tensile strength. Someone is telling me that there is a direct correlation between UTS and the rockwell test. I don't believe that they are interchangeable. I can't understand how the pull test employed by UTS testing directly corelates to a materials resistance to a compressive depression. I don't believe that different materials with the same rockwell will have the same UTS. Can anyone offer some insight?
Hi Michael
Great query, in part I would agree with your dispute.
First I would like to stress that typical hardness scale conversion tables and conversions to ultimate tensile stress are at best approximate. The tables are built up through comparison and not a magical formula.
Hardness measurement particularly in the steel industry is commonly used as a guide to UTS values as the test is quick and relatively easy.
With a specific material and enough comparative tests, quite accurate correlations can be made. But, it must be remembered that while hardness and strength have a close relationship, the tests and properties measured are very different and you cannot expect to have a universal correlation, particularly when considering different test materials.
Regards Gordon
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