A Study on Plastic Working of Alloys in Their Mashy State-The Second Report

Abstract

SummaryIn the preceding report1 presented at the 15th International MTDR Conference, the authors made it clear that flow stress of alloys in their mashy state (in the temperature range over the solidus line) is as small as. 1/4 to 1/5 of that in the temperature range for conventional hot working and showed the development of extrusion in the mashy state as an entirely new working process. There remain, however, many problems to be clarified about the deformation behaviour of alloys in their mashy state.Of these problems, the effects of strain, of strain rate and of the dimensions of the specimen on flow stress were investigated by means of uniaxial compression tests.Extrusion tests were also made with aluminium-copper alloy, silver solder and brass, and the working conditions under which sound products were obtained were investigated. The results were as follows:(1) The relationship between flow stress and solid fraction for a wide range of strain rate was clarified. (2) The effect of specimen dimensions on the flow stress in the compression test was clarified. (3) The mechanism of deformation or flow behaviour of alloys in their mashy state was presented. (4) Bars were successfully extruded in a reduction up to 99.6 per cent for aluminium-copper alloy and silver solder, and in the reduction of 99 per cent for brass. (5) Tubes were successfully extruded in a reduction up to 98.7 per cent for aluminium-copper alloy. (6) In the extrusion of bars, products were sound when the solid fraction was high and the bearing length was appropriately long.