The aim of this study is to clarify the effect of the process conditions such as dimensions of material, die and applied stress on the density distribution in the sintered steel after cold forging by Finite Element Method (FEM) analysis. The analysis model was a porous material model with axial symmetry. A polynomial approximation technique calculated a flow stress curve for the true stress-true strain curve obtained by the compression test of the sintered cylindrical specimen. The FEM analysis of cold forging was conducted using a simplified circular cone shape model
to increase local density and reduce the cold forging load. In the analysis, a closed die forging model was used. The tip angles of the circular cones and the opening angle of the die were 90, 60 degrees, and 120 degrees, respectively. As a result, it was found that the relative density of the tip increases up to 550-600 MPa regardless of the tip angle. Furthermore, the sharper the tip angle, the higher the density enhancement in the tip neighborhood portion. These findings will be helpful in the automotive industry.

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