Thermal mechanical behavior and microstructure characteristic of microalloyed CrMo steel under cross deformation

Pipes with a diameter of 177.8 mm were prepared by the cross deformation of an Nb, V and Ti microalloyed CrMo steel. Equivalent strains of pipe making process and their effect on microstructure evolution were investigated. A thermal mechanical simulator was employed to simulate the conditions of the pipe making at different elevated temperatures. Microstructure was studied using a transmission electron microscope and an X-ray diffractometer. It was found that the (1 1 1) fiber formed after the pipe making has been inherited in the steel pipes after heat treatment, and austenite recrystallization of the steel begins at 1223 K, in good accordance with the predicted recrystallization start temperature.