The Relative Validity of Coefficient of Friction and Interface Friction Shear Factor for Use in Metal Deformation Studies.
Technical rept. 1 Apr 69-14 Aug 70,
WESTINGHOUSE ASTRONUCLEAR LAB PITTSBURGH PA
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The relative validity of the concepts of constant coefficient of friction micro and constant interface friction shear factor m as quantitative indices for defining friction stresses existing in metal deformation operations is investigated by means of the ring compression test technique. Material flow stress values obtained by ring compression tests using mathematical formulae based upon both concepts in question are compared with flow stress values obtained on the same material by the accurate Polakowski technique which is not based upon any mathematical concepts. Flow stress values obtained by analysing ring compression test results using the concept of constant interface friction factor are found to be consistently lower than the values obtained using the constant coefficient of friction concept, and in good agreement with results obtained using the Polakowski technique. For this reason, it is concluded that the concept of constant interface shear factor m is the more realistic as a quantitative index for friction stresses existing in metalworking processes. Author