A study on the superplasticity of brass and its applications

This paper studies the conditions for the superplasticity of two CuZn alloys. Tests have been made with commercial HPb 59-1 brass bar and H62 brass bar, which were machined into tensile specimens. Then the specimens were subjected to heat treatment in order to meet the requirement of fine microstructure for superplasticity. Tensile tests have been carried out at different temperatures and tensile rates on a mechanically-operated high-temperature material testing machine.

Tests have shown that the superplasticity of HPb 59-1 brass occurred at a temperature of 620°C and a tensile rate of 0.3 mm min⁻¹ with a ductility of ∼500% without fracture, and that of H62 brass at a temperature of 750°C and a tensile rate of 0.2 mm min⁻¹ with a ductility of ∼624% without fracture.

This paper also studies the relations between the strain-rate and the temperature of the two materials, and makes observations on the microstructural changes in the surfaces of the specimens both before and after the tensile tests, using an optical microscope and a scanning electron microscope.

On the basis of superplastic tensile tests superplastic forming of HPb 59-1 brass is also studied.