Innovative square cogging to enhance void closure efficiency during forging of continuously cast round blooms

Kim, Namyong; Ko, Dae-Cheol; Tyne, C. J. Van; Han, Sang Wook; Abolhasani, Daniyal; Moon, Young Hoon

doi:10.1007/s12289-022-01709-0

Cited by 5 publications

(1 citation statement)

References 36 publications

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“…The cogging process is an open die forging process performed to enhance the mechanical properties of a material by refining its grain structure and eliminating internal defects [29][30][31][32][33]. In the cogging process, a billet is positioned between two dies, and the billet is repeatedly rotated and compressed between the dies to reduce its cross-sectional area and achieve a specific cross-sectional shape, such as circular, rectangular, or octagonal [34]. This compression is applied repeatedly along the length of the material, thus resulting in elongation in the longitudinal direction.…”

Section: Application To the Cogging Processmentioning

confidence: 99%

A Geometry-Dependent Void Closure Model Considering Void Deformation and Orientation Changes during Hot Metal Formation

Kim

Park

Kim

et al. 2023

JMMP

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In this paper, a void closure model applicable to the general hot forming process has been proposed. Through the representative volume element (RVE) method, the influences of void shape, orientation, and stress state on void closure tendency were analysed. The void closure model was established so that it could consider these cross effects. The model calculates the changing void radius and orientation during deformation by considering the rate of change of the parameters affecting void deformation with respect to the effective strain. The model predicted the void closure tendency well on the RVE scale and predicted the void closure adequately in a multi-stage process with random voids. The results were compared with the stress-triaxiality-based (STB) model, which showed that the void closure model proposed in this study is applicable in general situations. A cogging process was analysed, and the degree of void closure at the end of each pass was compared with the calculated results of the void closure model. For the experimental verification of the proposed model, spherical and ellipsoid voids were placed in a rectangular specimen, and the radii of the voids after compression were measured. The measurement results were compared with the calculation results of the proposed model.

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