티타늄의 THP공정 중 수소화 과정 수치해석 = Numerical Analysis of Hydrogenation Kinetics during Thermohydrogen Processing of Titamium

다국어 초록 (Multilingual Abstract)

A fixed grid, finite volume model was applied to investigate hydrogen absorption, diffusion and moving boundary α/βphase transformation that occurs during hydrogenation and homogenization annealing of cylindrical titanium specimens. Effects of parameters such as temperature, specimen radius, amount of added hydrogen on the times required for hydrogenation, for completion of α/βphase transformation and for homogenization were studied. It was found that hydrogen absorption rate is mostly influenced by surface reaction rather than solid-state diffusion. Time for hydrogenation becomes somewhat shorter with increase of temperature, due to decrease of hydrogen saturation concentration in spite of large increase of diffusivity and reaction rate constant. It increases almost linearly with increasing specimen radius or with amount of hydrogenation, showing positive deviation from linearity due to increase of diffusion resistance or surface hydrogen concentration. The completion of α/βphase transformation and homogenization are finished quickly with raising temperature due to increase of diffusivity and decrease of equilibrium hydrogen concentration in the βphase. They are nearly proportional to the square of specimen radius. With increase of the amount of added hydrogen, the completion of α/β phase transformation and homogenization are finished quickly during annealing due to the progress of α/β phase transformation during hydrogenation (Received August 23, 2003)