Energy-based assessment of residual plasticity in cold-formed low-carbon steel tube grooves

Abstract Cold-forming broaching with a shaped tool represents a contemporary method for forming the geometry of internal surfaces with a periodic profile via plastic deformation. A key limitation of this process is the progressive depletion of the material’s plasticity during groove formation, which leads to the degradation of mechanical strength properties. This study presents an experimental investigation into the mechanics of deformation, specifically examining the influence of tool geometry on the parameters governing deformation-induced strengthening of the material, as well as assessing the residual plasticity during the formation of internal grooves. Fracture work calculations for grooved specimens produced via сold forming broaching revealed that the specific fracture energy decreases with reductions in both the tool tooth sharpening angle and the base width of the trapezoidal profile. In order to accurately define сold forming broaching process parameters for different materials, deformation paths were constructed for the most critical points within the workpiece. The stress–strain state was evaluated using the LS-DYNA finite element software. The study establishes the impact of both the inclination angle of the tool tooth and the base dimension of its trapezoidal section on the residual plasticity resource of the workpiece.