Microstructure Evolution of a V-N Steel During Seamless Tube Hot Rolling

摘要

This work presents the microstructure evolution of a V-N steel during seamless tube rolling in a continuous mandrel mill. This evaluation was performed through hot torsion simulation. The use of this technique depends of a careful thermomechanical cycle characterization, in terms of its main metallurgical parameters: deformation, deformation rate, temperature, interpass time and cooling rate. After that, a simplification in the thermomechanical cycle was done, due to the unavoidable limited capacity of hot torsion machines to replicate industrial parameters. In this way, the hot torsion simulation was adapted and samples were obtained by interruption of cycle in selected steps. These samples were analyzed by optical microscopy and a mathematical model was adjusted to the austenite grain sizes measurement from the quenched samples. Both, simulated and mathematically predicted final microstructure showed good correlation whit industrial scale results.