A STUDY OF VOID CRUSHING IN LARGE FORGINGS II - ESTIMATION OF BONDINGEFFICIENCY BY FINITE-ELEMENT ANALYSIS

Larger ingots are required in the steel industry because the major par ts of many products are needed as one large body in order to obtain hi gher 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 o f the study being to estimate the bonding efficiency by the finite-ele ment method and using the estimation method proposed in a previous pap er. From the thermo-viscoplastic finite-element method, a boundary con dition was imposed on the surface of an internal void. Experiments wer e also carried out in order to compare the bonding efficiency with tha t of the proposed modelling, in which the required data were obtained from the finite-element analysis. The results calculated using the pro posed model are in good agreement with the experimental results. Accor ding to the variation of the position of the void and the change of di e shape, the bonding efficiency is estimated and the height reduction of forging for the elimination of the voids is correctly estimated thr ough analysis of the bonding process. (C) 1997 Elsevier Science S.A.