Surface tension of molten iron and molten ferroalloys was measured by a sessile drop method in order to make clear the effect of P and Ti on surface tension of liquid iron in the concentration range of less than 1 mass%. Based on the present results, effect of P, Ti, Mn and C on entrapment of alumina inclusion in a solidified shell was discussed, taking account of gradient of boundary tension between alumina inclusion and molten iron in a boundary layer at a solidification front.
