3D coupled macro–microscopic finite element modelling and simulation for combined blank-forging and rolling process of alloy steel large ring

Radial–axial ring rolling (RARR) is an advanced plastic rotary forming technique used to manufacture seamless large rings. In RARR, blank-forging and rolling are the two consecutive forming processes. The former plays an important role to the latter as it has important genetic influence on rolling. However, this influence was not considered in the current finite element model (FEM) researches of RARR, in which the geometry and thermodynamic state of the ring blank were idealized and the microscopic deformation behaviors were rarely studied. In this paper, a 3D coupled macro–microscopic finite element (FE) model combining blank-forging and rolling processes of AISI 4140 steel large ring is firstly developed under SIMUFACT software environment, and its reliability is verified experimentally. Based on the valid model, the evolution and distribution laws of strain, temperature, grains sizes, dynamic recrystallization from the ingot to ring blank to rolled ring during the process are revealed. The results obtained show that: (1) the strain and temperature distribution are neither uniform nor symmetrical before or after rolling. (2) Higher temperature and larger strain both contribute to the higher dynamic recrystallization fraction. (3) Higher deformation temperature drives the dynamic recrystallized grains sizes bigger while higher strain rate decreases it.