Journal of Materials Processing Technology, 23 (1990) 21-28 21 Elsevier THE EFFECT OF DEFORMATION ON THE CORROSION RESISTANCE OF COATED STEEL SHEETS JERZY GRONOSTAJSKI Technical University of Wrodaw, Poland WALEED JALAL ALI University of Mosul, Iraq MAGDY SAMUEL GHATTAS Mansoura University, Egypt (Received September 18, 1989; accepted January 9, 1990) Industrial Summary Maps of the resistance to corrosion in a salt-water solution of specimens deformed by linear- and complex-strain paths have been determinedexperimentally for polyethylene-, acryl- and PVC- coated zinc hot-dip galvanizedsteel sheets. The complexstrain paths contained two linear defor- mations: in the first stage of deformation the specimenswere in the in-plane condition and in the second stage in the out-of-planecondition. It has been found that over the whole range of linear- strain paths and in the second stage of complex deformation the corrosion resistance decreases when the strain ratio ~2/~1increases. Equi-biaxial pre-deformation effects a greater deterioration of the corrosion resistance than does uniaxial pre-deformation. The corrosion resistance is also a function of the thickness of the zinc layer. Introduction The demand for good corrosion protection in wide variety of finished prod- ucts over recent years has resulted in the increasing use of coated steel sheets. A surface coating is essential not only for the protection, but also for the dec- oration, of a very wide range of products. The use of coated steel in the motor car industry is becoming a quite common practice, enabling a reduction in material thickness, in car weight and in fuel consumption and giving better corrosion protection. The forming processes for such steel sheets are generally limited by the same phenomena as arise during the deformation of uncoated steel sheets, namely, plastic instability and fracture [1,2]. Special attention has to be paid to the influence of the deforming conditions on the performance of the coating as regards protection against corrosion. The adhesion of the coating must remain good and the surface should not be dam- 0924-0136/90/$03.50 © 1990---Elsevier Science Publishers B.V.