A novel deep drawing process for aluminum alloy sheets at cryogenic temperatures

Abstract

Abstract To overcome the low drawability of aluminum alloy sheets at room temperature (RT), a novel deep drawing process at cryogenic temperatures is proposed. Uniaxial tensile tests were carried out at RT, −130 °C, −150 °C, −160 °C and −196 °C, respectively, and the desired temperature of cryogenic deep drawing was obtained. Based on a newly-designed cryogenic deep drawing system, deep drawing experiments of an Al-Cu-Mn alloy sheet were conducted at different cryogenic temperatures. The material flow, drawing ratio, drawing load, thickness distribution and Vickers microhardness of the drawn cups at both RT and cryogenic temperatures were discussed in detail. It was found that the deep drawability was significantly enhanced as the temperature decreased to −160 °C. The limiting drawing ratio at RT was 1.80, while that at −160 °C increased by 15.6% to 2.08. Similarly, the average cup height (89.5 mm) at −160 °C was found to be 50.2% higher than that at RT (59.6 mm). The cryogenically drawn cups exhibited slight localized thinning, uniform thickness distribution, and a large drawing height and drawing load. In addition, the enhancement of the deep drawability was illuminated via microstructural observations of the fracture morphology and dislocation evolution at cryogenic temperatures.