Investigation of Interface Friction Between Tool and Workpiece Materials under Conditions of Plastic Deformation

摘要

An investigation was carried out on interface friction between workpiece and die material under conditions of plastic deformation. Evaluation was made by means of two simulating tests: a twist-compression technique provided conditions of enforced sliding, whereas in ring upsetting experiments sticking friction was predominant. Hot rolling tests were performed in order to correlate the results with conventional metalworking practice. 7075 Al, Ti-6Al-4V, 4140 steel, TZM, and Hastelloy X were used as workpiece materials. These were deformed with tools of H12, 4140, WC, Al2O3-coated H12, boronized 4140, chromized 4140, and titanium carbide-coated 4140. Significant variations in friction due to die surface composition were observed, the effects being more marked with enforced interface sliding. The most promising anvil material from both frictional and mechanical aspects was boronized 4140. Good correlation with existing theories of adhesion was obtained, although these theories did not fully account for the observed effects of workpiece hardness and alloy composition. The presence of a surface oxide on the workpiece reduced the friction in elevated temperature tests with all materials except Hastelloy X, the oxide of which had no effect on friction under the conditions investigated. (Author)