Wind turbine main bearing rings with non-standard cross-sections are large, and a single rolling operation can hardly satisfy the simultaneous requirements of stress uniformity and dimensional accuracy; how the as-rolled state is inherited by the subsequent hot bulging remains unclear. A coupled thermo-mechanical model of the rolling-bulging sequence of a GCr15SiMn ring was therefore established in Abaqus/Explicit, transferring the geometry and the stress, plastic-strain and temperature fields across the two operations. With all bulging parameters fixed, five initial rolling temperatures (1040–1160 °C) were compared. The rolling stage was validated experimentally, the relative errors of the predicted outer diameter, inner diameter and wall thickness being below 0.37%, 0.28% and 2.5%, respectively, and the mesh-convergence deviation below 2%. Bulging reduced the mean stress by 21.9–35.6% and preserved the as-rolled uniformity ranking, the lowest stress standard deviation (3.46 MPa) occurring at 1130 °C. The outer- and inner-diameter roundness errors decreased from 6.29–7.61 and 4.13–5.14 mm to 1.05–1.44 and 0.80–1.35 mm, corresponding to correction ratios of 81–83% and 74–81%; the retained fractions stayed within 17–19% and 19–26% of the as-rolled error, so bulging scales the inherited shape error rather than equalising it. Considering dimensional accuracy and the stress state together, 1130 °C is recommended as the optimum, with 1100–1130 °C as the preferred process window. The bulging results are simulation predictions pending full-size experiments.

The forming quality of large wind turbine main shaft bearing inner rings directly determines the service life and operational reliability of wind energy equipment. Yet the plastic deformation mechanism and stress–strain evolution of GCr15SiMn bearing inner rings during asymmetric cross-section radial–axial rolling remain poorly understood. Stress–strain curves from isothermal hot compression tests were used to build a three-dimensional finite element (FE) model of inner ring radial–axial rolling, validated by dedicated rolling experiments. The effects of drive roll rotational speed, initial rolling temperature, and radial–axial feed speeds on the stress and strain fields were systematically investigated. Results show that material flow velocity on the outer surface of the radial deformation zone is 100–200 mm/s higher than on the inner surface. The velocity difference between the upper and lower end faces in the axial deformation zone stays below 100 mm/s, confirming synchronous end-face forming. Peak equivalent stress reaches 81.5 MPa in the radial rolling stage and 75.6 MPa in the axial rolling stage. Standard deviation of stress (SDS) and plastic strain (SDP) quantify field uniformity; the most uniform distributions occur at 3.5 rad/s (SDS = 15.09) and 1100 °C (SDP = 4.18). These findings provide a theoretical basis for rolling process optimization and precision forming quality control of asymmetric cross-section wind turbine bearing inner rings.