Estimation of the Grain Size Number and Microstructure Analysis of AA6061 Alloy Flow Formed Tubes

Flow forming process is a chipless metal forming process used for the production of high accuracy axi-symmetrical cylindrical components. During this process there is an increase in tube length and decrease in thickness without any change in internal diameter. Generally forming is performed with a single roller or three rollers over a rotating mandrel and the present work is with three roller setup. The work material is plastically deformed in the radial direction by compression due the rollers and made to flow in an axial direction and the thickness reduction is achieved with single pass. The AA6061 aluminum alloy, usually used in defense components is considered for flow forming. The mechanical properties of this alloy are dependent on the rate at which the alloy is heated and quenched. Solution treatment has been carried out at 400 °C for 2 h followed by quenching in water. Microstructure of the finished product has been studied by using SEM and grain size is estimated for different reduction ratios and stagger distance using the intercept method.