Hydraulic bulge testing of dual phase steel tubes produced using a novel processing route

Dual phase steel tubes were produced using a novel processing sequence. For this new processing technique, a ferrite/pearlite sheet is formed into steel tubes, which are then normalized, induction heated to an intercritical temperature, quenched, and tempered, producing a dual phase microstructure. In the present study, Fe-0.19C tubes were processed to achieve tensile strengths of approximately 600 MPa. Tubes were evaluated in a hydraulic bulge test apparatus and the results were compared with the axial tensile properties of the tube. Pressure-displacement data from the hydraulic bulge test was converted into effective stress–strain data using two separate procedures. The flow strength in uniaxial tension was higher than flow strength obtained from the hydraulic bulge test although similar strain hardening behavior was observed. Predictions of the maximum bursting pressure agree with the experimental data. Preliminary results suggest that formability issues related to the weld line are not present in tubes that have been produced using the new processing technique.