真空感应熔炼核级316H不锈钢氮含量变化规律研究OA

To address the issue that it is difficult to control the nitrogen content in 316H austenitic stainless steel melt during vacuum smelting,which requires repeated addition of nitrogen-increasing alloys,leading to long smelting cycles and high costs,this study uses high-purity metals and alloys as raw materials to melt 3 16H stainless steel in a 50 kg vacuum induction furnace.The effects of different melting atmospheres,melting pressures,and types of nitrogen-increasing alloys on the nitrogen content in the molten steel were investigated.Additionally,the thermodynamic and kinetic behaviors of the denitrogenization reaction during the vacuum smelting were analyzed.The results show that under constant pressure,the solubility of nitrogen in steel increases with increasing temperature;when equal amounts of alloying elements are added,pressure has a greater impact on the nitrogen solubility than temperature.The equilibrium nitrogen content in the alloy melt decreases with an increase in the vacuum degree and smelting temperature,and the changes in vacuum degree have a greater effect on the equilibrium nitrogen content under high-vacuum degree conditions.Under nitrogen protection and the same melting pressure,using manganese nitride as an additive has a better nitrogen-increasing effect than using chromium nitride.Under the conditions of a smelting temperature of 1 600 ℃,a 50 kPa argon vacuum pressure and a 50 kPa air vacuum pressure,the denitrogenization reactions during vacuum induction melting of 316H stainless steel are both limited by mass transfer from the interior of the molten steel to the liquid-phase boundary layer,and the reactions follow first-order reaction kinetics,with the mass transfer coefficients of 0.35×10-3 cm/s and-0.858×10-4 cm/s,respectively.Meanwhile,the nitrogen content varies within the small range of 0.042％to 0.044％.