Dynamic recrystallization rules in needle piercing extrusion for AISI304 stainless steel pipe

The dynamic recrystallization (DRX) rules are the significant foundation for the effective control of DRX behavior, consequently achieving fine grains and qualified microstructure in the needle piercing extrusion for AISI304 stainless steel pipe. A reliable multi-scale FE model was developed for the extrusion process of seamless AISI304 stainless steel pipe (d29 mm×4.5 mm) under the DEFORM-2D software environment, and then the influence rules of the key extrusion parameters were numerically unfolded, namely the initial billet temperature and extrusion speed, on the DRX volume fraction, average grain size and their distributions by comprehensive simulations. The outcome establishes the basis and guidelines for the optimal design and steady control of the extrusion process in terms of the microstructure of the extruded pipe.