A study of void crushing in large forgings II. Estimation of bonding efficiency by finite-element analysis

Abstract

Larger ingots are required in the steel industry because the major parts of many products are needed as one large body in order to obtain higher quality. In large ingots, internal voids have to be eliminated so as to obtain sound products. Void crushing is carried out in at least two steps, i.e. void closing and hot pressure bonding. This study is concerned with hot pressure bonding of internal voids, the objective of the study being to estimate the bonding efficiency by the finite-element method and using the estimation method proposed in a previous paper. From the thermo-viscoplastic finite-element method, a boundary condition was imposed on the surface of an internal void. Experiments were also carried out in order to compare the bonding efficiency with that of the proposed modelling, in which the required data were obtained from the finite-element analysis. The results calculated using the proposed model are in good agreement with the experimental results. According to the variation of the position of the void and the change of die shape, the bonding efficiency is estimated and the height reduction of forging for the elimination of the voids is correctly estimated through analysis of the bonding process. (C) 1997 Elsevier Science S.A.