Effect of heat treatment temperatures on formability of SS 304 during tube hydroforming process

Tube hydroforming is a special process which utilizes a liquid medium to form the tube into required shape. This method has an advantage of attaining uniform pressure all through the tube at any time throughout the process. The forming limit curve (FLC) of SS 304 tubes at different annealed temperatures viz., 150 °C, 200 °C and 250 °C were investigated and compared with as received condition. Effects of annealing temperatures on FLC and bulge height of the hydroformed tube were studied. Numerical simulation of FLCs in tube hydroforming with different L/D ratios and diverse boundary settings were judged to extend wide variety of strain paths. The obtained FLD from the simulations were compared with other two different models to predict the accuracy of the FLD models. Numerical simulations confirmed that the annealing temperatures had an effect on the FLC of hydroformed tube. The forming limit increased with temperature up to 200 °C, and decreased slightly at 250 °C temperature.