Simultaneous Control of Shape and Properties of AZ31 Magnesium Alloy Sheets by Incremental Forming

Abstract

In this study, simultaneous control of shape and hardness of AZ31 magnesium alloy sheets by incremental forming process was proposed. Influences of working temperature, giving strain and heat treatment temperature on hardness were investigated. AZ31 magnesium alloy sheets were formed into pyramidal shape by incremental forming process at 100°C and 200°C. Major strains given to the pyramidal faces were 0.1, 0.2 and 0.3. After forming, heat treatment was carried out at various temperatures. Combination of final shape and total equivalent plastic strain were changed by multi-step forming and hardness distribution was measured. From the experimental results, it was found that when heat treatment was done at 200°C for 10 min after forming at 200°C, hardness of the specimen became higher than that of as received one. When heat treatment was carried out at 175°C for 60 min after forming at 100°C, hardness of the specimen also increased. In the case of multi-step forming, strain was accumulated at forming temperature of 100°C and hardness increased, but not at the forming temperature of 200°C. By multi-step forming at 100°C, asymmetric hardness distribution with symmetric shape was realized and simultaneous control of shape and hardness was succeeded.