Influence of the microstructure of forged and machined parts on the residual stresses

摘要

One of the first stages in component design is the choice of material, in particular the steel grade, together with the appropriate manufacturing process. The aim of the methodology proposed is to compare the geometrical and metallurgical qualities of steel parts throughout the manufacturing process. The axisymmetrical geometry of the parts was first of all defined for a typical manufacturing process, including forging and machining steps, starting from rolled blanks. Forming involves two elementary forging operations, corresponding to extrusion and upsetting. The forged parts are subsequently machined, by turning and drilling. Initially, only cold forging and finish turning processes were considered, for two low alloyed steel grades with different microstructure. An experimental investigation was conducted to determine the cutting conditions and particularly the influence of the cutting conditions on residual stresses in the axial and circumferential directions. As regard the cutting speed, only the tangential residual stresses show significant variations. Concerning the feed rate, a significant evolution is only observed on the longitudinal residual stresses.