The application of a phosphate coating ontogalvannealed steel strip has been shown to lower the coefficient offriction of its surface. Such prephosphate treatments cause anenhancement of the forming properties of the galvannealed steelstrip. The correlation between the surface coefficient of frictionand the deep drawing properties of galvannealed steel strip hasbeen examined using cup tests. The tests have been performed suchthat measurements of the maximum load required to form a cupwere made as a function of hold-down load. An equation thatpredicts the cup forming load as a function of the coefficient offriction and the geometrical and flow properties of the testspecimen has been used to isolate the effect of surface frictionfrom the measured data. The surface coefficient of friction valuesdetermined through cup testing of prephosphated galvannealedsteel samples were found to reflect the trends established by drawbead simulator (DBS) friction tests. The major difference betweenthe two tests was found in the determination of the value of thecoefficient of friction for non-prephosphated galvanneal.
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