Friction law in dry metal forming of materials with work hardening

Abstract Frictional behavior in dry forming of materials with work hardening is investigated by using a side stretching type tribometer and a testing method under high contact pressure. A series of experiments are carried out by using specimens made of a steel sheet and a pure copper sheet. It is found that the friction law for materials without work hardening can be applied to materials with work hardening by using the flow stress Y corresponding to the effective strain of 0.08 in the non-dimensional average pressure p a / Y . The friction law is applicable to materials with pre-strain e 0 by using the flow stress Y corresponding to the effective strain of ( e 0 + 0.08) in the non-dimensional average pressure p a / Y .