ABSTRACT
Autofrettage and Re-autofrettage processes have been used to generate compressive residual stress at the near bore area of the cylinder to enhance the load carrying capacity of the cylindrical pressure vessels. These processes' main drawback appears in the detrimental high tensile residual stress at the outer part of the cylinder. On the basis of these findings, internal surface autofrettage combined with external surface autofrettage processes have been used to improve not only by increasing of compressive residual stress at the near bore area but also by decreasing of tensile residual stress at the outer surface area. For these cyclic plasticity processes, an accurate finite element model governed by non-linear kinematic hardening model (Chaboche model) has been used. This model simulates the measured stress-strain actual behavior for NiCrMoV125 steel alloy.