FLOW BEHAVIOR OF COMMERCIAL GRADE TI-6AL-4V WITH LAMELLAR STRUCTURE IN ISOTHERM FORGING AND KINETIC ANALYSIS OF PROCESS

In this paper, plastic flow behavior and micro structural evolution of Ti-6Al-4V alloy in temperature range of 750-1050^oC and strain rate range of 0.001-0.1 (S^-1) in isotherm compression condition were investigated. The purpose was to estimate activation energy of globularization of lamellar structure and analyze this process kinetically. True Stress-strain curves obtained at the temperatures below 950^oC indicate a limited amount of flow softening imputed to a dynamic recrystallization occuring at about 950^oC. In contrast, at higher temperatures, the flow stress increases linearly with plastic strain until at temperatures about 1015^oC where flow stress becomes nearly independent of the temperature. By analyzing flow stress data via Zener-Hol-lomon and sellars equation, Q activation energy of dynamic recrystallization was estimated and structural equation of plastic flow was obtained, whixh were comparable to results raeched by other investigators.