Experimental and Finite Element Investigation of Titanium Tubes Hot Gas Forming and Production of Square Cross-Section Specimens

Tube-shaped equipment is among the most applicant titanium alloys which are widely used in chemical, Marine, and aircraft industries. Most of the titanium tube-shaped products are made of commercially pure titanium or low strength titanium. One of the greatest limits in manufacturing titanium products is low formability of titanium in ambient temperatures. The process of hot tube gas forming is one of the promising methods used to manufacture the tube-shaped products. In the current study, finite element and experimental process of hot tube gas forming were investigated to produce a square cross section product from a commercially pure titanium tube (Grade 2) in 840 °C. The effect of gas pressure increase rate on forming the tube was also investigated. The results obtained through different experiments showed that the reduction of gas pressure increase rate in tubes, not only provide sufficient time to temperature distribution and uniform forming of products, but also decrease the strain rate in tube walls and consequently decrease the probability of tube tearing. The microstructural investigation revealed that recrystallization occurred during the forming process and final product contains coaxial grains.