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Abstract
Observations are reported on plane-strain upsetting, between unlubricated flat punches, of powder preforms of varying density at 1160°C (1435 K). Macroscopic deformation behaviour is characterized by the pressure/strain relationship and by the ratio of lateral to vertical flow. Increased preform porosity affects lateral flow similarly to increased friction in forging of dense material.
Densification is studied as a function of strain and pressure. Lower preform density requires not only larger strains but also higher pressures for a given final density.
The density distribution in typical forgings is charted by means of hardness measurements. Zones of incomplete densification are revealed where local pressure was reduced by lack of constraint, or where strain was impeded by friction effects.
Notes
* Manuscript received 7 August 1970. Contribution to a Symposium on “The Forging of Powder Preforms” held in Eastbourne on 16 and 17 November 1970.