Abstract:Stainless die with micro-groove and micro-hole have been designed and manufactured, which has been used to study superplastic microforming of 2091Al-Li alloy by means of superplastic forming. Micro-extrusion test shows that the selected material has good microformability which is evaluated by the specially developed method. Effects of pressure on forming have been analysed. At 510℃, the width of ribs are 160μm and 140μm respectively in case 1 (stress 63.69MPa, dwell time 6min) and case 2 (stress 79.62MPa, dwell time 5min). SEM and metallographic microscope have been used to analyse the surface of the formed micro-rib and micro-protuberance. At 500℃, stress 79.62MPa and dwell time 5min, the diameter of the micro-protuberance is 150μm. Through analysis of flow lines of the formed micro-rib specimen, behavior of material could be understood well.

Key words: superplasticity; microforming; extrusion; 2091Al-Li alloy