The influence of tool steel microstructure on friction in sheet metal forming

The frictional behavior of a number of conventional tool materials used in the sheet forming industry has been studied by a recently developed tribotester based on flat-die strip drawing. The main objective was to study the frictional performance of the materials and correlate the tribological behavior mainly to the microstructure. Tooling materials tested ranged from powder metallurgical tool steels to nodular cast iron as well as a novel abrasion-resistant cast iron, Carbide steel. A high strength uncoated sheet material commonly used in sheet forming applications was used as a reference sheet material in all tests. The microstructural characterizations of the tool materials were done by SEM image analysis and XRD analysis. Surface roughness characterization was done by 3D optical analysis. A direct correlation between the amount of carbides and the friction coefficient could not be stated based on the specific experimental conditions.