Abstract
High nitrogen stainless steels have got a lot of attention recently because of its high material performance. In Europe, high nitrogen steels are produced through PESR (Pressurized Electro Slag Remelting) process. Silicon or chromium concentration is increase because silicon nitride or chromium nitride are used as nitriding agent in this process. Gaseous nitriding during melting by pressurized induction furnace is a favorable method to avoid this problem. Clarifying the nitrogen dissolution rate in the steel melt and formation condition of pore in ingots is important for operation. However, behavior of nitrogen dissolution into molten steel and formation of pore during solidification under pressurized atmosphere have not been cleared in larger scale furnace. Therefore, authors have investigated it by the use of 500 kg pressurized induction furnace. The results are follows: (1) Nitrogen dissolution rate of the 500 kg furnace was slower than that of 50 kg furnace. It is thought that this comes from the difference of surface detention time of steel melt. (2) Nitrogen concentration is able to predict with using appropriate thermodynamic parameters. (3) Nitrogen limit is proportional to square root of nitrogen pressure. Pore formation condition is same for the both size ingots and sample that directly took from melt before casting.
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