Abstract
New experimental work on the hydrostatic extrusion of rod and wire at fluid pressures up to 115 tonf/in2 is reported. The materials studied were copper, aluminium, magnesium, titanium, zirconium and niobium alloys. Results demonstrating the effects of billet geometry, lubrication and fluid medium on extrusion pressure and product finish are presented and discussed.
The influence of extrusion ratio on pressure was determined and results are compared with published data. Theoretical predictions of extrusion pressure, based on flow stress in uniaxial compression, agreed well with experimental results for cubic metals. However, there were anomalies with hexagonal metals, and it was found that these could be resolved if tensile rather than compressive or torsional flow stress data were used.
In the extrusion of wire from straight and coiled billets it was observed that higher pressure was required to extrude smaller wires, for an equivalent area reduction. The significance of this apparent scale effect is discussed.
Metals with cubic or hexagonal structure were extruded into fluid pressurized at various levels up to 40 tonf/in2. The mechanical properties of the products were determined, and some unexpected results were obtained.
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