The Effect of Oxygen Partial Pressure on Heat Transfer and Solidification





The effect of oxygen partial pressure (<i>P</i><sub>O<sub>2</sub></sub>) in different gas atmospheres on heat transfer, cast structure and secondary dendrite arm spacing in droplet solidification process has been investigated. It has been found that the <i>P</i><sub>O<sub>2</sub></sub> of the gas affects solidification process and undercooling. As <i>P</i><sub>O<sub>2</sub></sub> decreases, at relatively high <i>P</i><sub>O<sub>2</sub></sub> (10<sup>−1.2</sup>–10<sup>−4</sup>) in 99.99% Ar and air atmosphere, heat flux is decreased and equiaxed zone ratio and secondary arm spacing are found to be increased. At intermediate <i>P</i><sub>O<sub>2</sub></sub> (10<sup>−14</sup> to 10<sup>−20</sup>) in Ar–H<sub>2</sub> atmospheres, heat flux and equiaxed zone ratio varies only slightly and secondary arm spacing is reduced. At low <i>P</i><sub>O<sub>2</sub></sub> (10<sup>−20</sup>–10<sup>−23</sup>) in Ar–5%H<sub>2</sub> atmosphere, heat flux increases dramatically and the equiaxed zone ratio and secondary arm spacing are reduced. The largest equiaxed zone is found with intermediate <i>P</i><sub>O<sub>2</sub></sub> levels in Ar–H<sub>2</sub> gas atmospheres, whereas the finest grains are obtained in Ar–5%H<sub>2</sub> gas in low <i>P</i><sub>O<sub>2</sub></sub> value.


  • ISIJ international

    ISIJ international 46(10), 1427-1431, 2006-10-15

    The Iron and Steel Institute of Japan

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