Die Wear and Galling in Stamping DP980 Steel

Abstract

Stamping of dual phase (DP) 980 steel creates higher deformation heat, contact pressure and friction force between the tooling and sheet steel. These, in turn, cause higher die wear and galling. Although various countermeasures have been adopted in production to prevent excessive wear associated with forming DP980 steel, the stamping die tryout process has not been revised accordingly to ensure that the die surfaces in contact with sheet metal have been hardened and coated. The effects of die hardness and lubrication conditions on die wear and galling in stamping DP980 steel during the die tryout process were evaluated at different contact pressures using the bending under tension (BUT) tester. A reciprocal cyclic bend test system (CBTS) of modifying bending under tension test was used to investigate wear and galling between a die in the tryout phase and in a production condition. The results indicate that the hardness of the die material dominates the galling and wear behavior in the die tryout phase. A better surface treated die material and an anti-galling strategy was also identified to decrease galling and wear in both die tryout and production.