Method for smelting low-aluminum high-nitrogen martensitic stainless steel in pressurization and induction manner

Abstract

The invention discloses a method for smelting low-aluminum high-nitrogen martensitic stainless steel in a pressurization and induction manner and belongs to the field of metallurgy, wherein the method is suitable for smelting. The low-aluminum high-nitrogen martensitic stainless steel comprises, 0.1%-0.6% of carbon, 0%-0.5% of manganese, 12%-24% of chromium, not larger than 1% of silicon, 0%-3% of molybdenum, 0.1%-0.6% of nitrogen, 0%-2% of nickel, 0%-1% of vanadium, not larger than 0.02% of aluminum, not large than 0.002% of sulfur and the balance iron and inevitable impurities. The method includes the specific steps of blending, material distribution, temperature increase after vacuumizing, high-pure argon filling after raw material melting-down, graphite adding for deoxygenation, industrial silicon adding for deoxygenation when the environment is vacuumized to 10 Pa, nitrogen filling and alloying, nickel magnesium alloy and rare earth adding for heat preservation for 5 min to 10 min, nitrogen charging and casting and the like.

Description

technical field [0001] The invention belongs to the technical field of high-nitrogen stainless steel smelting, and in particular relates to a method for pressurized induction smelting low-aluminum high-nitrogen martensitic stainless steel. Background technique [0002] High-nitrogen martensitic stainless steel refers to martensitic stainless steel with a nitrogen content greater than 0.08% in steel. The addition of nitrogen in martensitic stainless steel expands the temperature range of the austenite phase region, effectively inhibiting the formation of δ-ferrite; while ensuring interstitial solid solution strengthening, the carbides can be refined, accompanied by nitrogen The dispersed precipitation of compounds, etc. not only significantly improves the strength and hardness of martensitic stainless steel, but also can still guarantee the original toughness of martensitic stainless steel. In addition, the addition of nitrogen is beneficial to improve the corrosion resistan...

AI Technical Summary

Problems solved by technology

At present, the production of high-nitrogen stainless steel mainly adopts the pressurized electroslag remelting process. The existing process has the following disadvantages: there is uneven distribution of nitrogen elements, and sometimes secondary remelting is required; Composite electrodes, but the cost is significantly increased; in addition, adding nitrides to the slag will cause the slag to boil, interfere with the melting process, and may cause the metal film at the electrode tip to be exposed to high-pressure nitrogen, which cannot control the absorption of nitrogen by liquid metal, etc.

However, due to the low solubility of nitrogen in martensitic steel, how to reasonably control the two-stage pressure of smelting and casting, accurately control the nitrogen content in high-nitrogen martensitic stainless steel, and avoid solidification defects is an urgent problem to be solved.

For high-nitrogen martensitic steel used as bearings, gears, and moulds, the use of aluminum deoxidation will produce a large amount of aluminum nitride in the steel, and excessive precipitation of aluminum nitride along the grain boundaries will cause hot embrittlement of the steel and cause forging transverse cracks , and it is easy to become the source of fatigue cracks, which significantly reduces its fatigue performance

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