PROCESS DESIGN BASED ON THE DEFORMATION MECHANISM FOR THE NONISOTHERMAL FORGING OF TI-6AL-4V ALLOY

Non-isothermal forging has been widely employed in the metalworking in dustry. Although the die-chilling effect is very significant in the no n-isothermal forging process, the process parameters of time and tempe rature are difficult to measure and control during non-isothermal forg ing. To cope with this problem, this study employs the thermal-coupled finite element method to examine and to establish the relationship be tween the process parameters and the deformation behaviour, then deriv ing useful design rules. The detailed process model based on experimen tal conditions, and the how stress model constructed by the localized linear fitting and interpolation method, were used in the finite eleme nt analysis. Consequently, the simulation of the non-isothermal forgin g of Ti-6Al-4V was performed, the predicted results agreeing well with those from experiment. Due to the large temperature gradient, the mod e of deformation in non-isothermal forging is different from that in i sothermal deformation. Therefore, a deformation mechanism for non-isot hermal forging was proposed in this paper to explain the deformation b ehaviour. Hence, the deformation mechanism governing the metal how of non-isothermal forging can provide guidelines for forging die design a nd process design. (C) 1998 Elsevier Science S.A. All rights reserved.