Superplastic forming characteristics of a CuZnAlZr shape memory alloy

The effects of temperature and pressure on the pressure forming of CuZnAlZr sheet was investigated under free bulging conditions using argon gas. The effects evaluated were the dome height measured at the dome pole, the specific thickness (the ratio of the actual thickness to the initial thickness) and the thinning factor (the ratio of the actual thickness to the average thickness). sults show that the dome height as well as the rate dhdt of change in dome height with respect to time increase with increasing temperature and/or pressure. The specific thickness decreases with increasing fractional height (the ratio of the height of a given point above the base line to the height of the pole), and the specific thickness at the pole decreases with increasing temperature and/or pressure as well. The thinning factor decreases with increasing fractional height. Furthermore, this decrease becomes more pronounced with an increase in either the forming temperature or the pressure. The thinning factor at the pole, as a function of the height-to-base ratio for all conditions except 550°C, 0.207 MPa and 600°C, 0.207 MPa, falls into the region of m = 0.3 and m = 0.75 curves. The optimum forming conditions for our specimens are 550–600°C, 0.31 – 0.414 MPa.