Improvement of Inline Cutting Device for Continuous-cast Slab in High-Ni Alloys

Abstract

An improvement has been carried out to minimize the time for cutting continuously cast slabs in high-Ni alloy by means of a torch-cut equipped with Fe and Al powder supply. Two major reasons why it was so tough to cut the slabs in high-Ni alloy were considered. Firstly, heat generation by torch-cut is insufficient to keep burning a slab for high-Ni alloy because Ni is a metal nobler than Fe or Cr. Secondly, fluidity of the flown melt formed by torch-cut of slab is lower for high-Ni alloy than for low-Ni stainless steel. The formed flown melt consists of a mixture of molten alloy and oxides. The flown melt for high-Ni alloy includes higher ratio of solid oxides which lowers the fluidity. In order to cut the slab against low fluidity of the flown melt, the cutting device was improved by increasing ability to supply combustion gas and powder. In addition, the powder ratio of Al to Fe was optimized as 25 mass%. Consequently, the improvement succeeded in shortening the time for cutting a slab to half for high-Ni alloy.