Method for smelting martensitic stainless steel P91 for boiler pipe

Abstract

The invention belongs to the technical field of smelting, and mainly relates to a method for smelting martensitic stainless steel P91 for a boiler pipe. The technological process of an electric arc furnace / medium-frequency induction furnace, an argon-oxygen refining furnace, an LF refining furnace, vacuum degassing, LF and continuous casting is adopted. Components for smelting the martensitic stainless steel for the boiler pipe comprise, by mass percent, 0.08%-0.12% of C, 0.30%-0.50% of Si, 0.30%-0.60% of Mn, not larger than 0.015% of P, not larger than 0.010% of S, not larger than 0.40% of Ni, 8.5%-9.5% of Cr, 0.90%-1.10% of Mo, 0.18%-0.30% of V, not larger than 0.30% of Cu, 0.03%-0.07% of N, 0.05%-0.10% of Nb, not larger than 0.020% of Al, not larger than 0.015% of [As], not larger than 0.010% of [Sn], not larger than 0.010% of [Pb], not larger than 0.010% of [Sb], not larger than 0.010% of [Bi] and the balance Fe and a small quantity of other elements. The method for smelting the martensitic stainless steel P91 for the boiler pipe aims to be low in inclusion content and delta-ferrite content and capable of achieving continuous casting production.

Description

technical field [0001] The invention belongs to the technical field of smelting, and mainly relates to a method for smelting martensitic stainless steel P91 for boiler tubes. Background technique [0002] P91 is a commonly used steel for subcritical and supercritical high-pressure boiler tube walls. The smelting method of EAF+LF+VD+LF is often used. This smelting method needs to use micro-carbon ferrochrome to adjust chromium during the LF refining process to prevent carbon high , the cost of higher carbon ferrochrome is higher than that, and at the same time, 6-8 tons of alloys are transferred in large quantities during the refining process of the refining furnace, and the smelting time of the LF furnace is more than 5 hours, which cannot meet the needs of continuous casting production. Contents of the invention [0003] The object of the present invention is to provide a method for smelting martensitic stainless steel P91 for boiler tubes with low P91 inclusion content a...

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Problems solved by technology

[0002] P91 is a commonly used steel for subcritical and supercritical high-pressure boiler tube walls. The smelting method of EAF+LF+VD+LF is often used. This smelting method needs to use micro-carbon ferrochrome to adjust chromium during the LF refining process to prevent carbon high , higher carbon ferrochrome is more costly than that, and at the same time, a large number of alloys are transferred into the refining furnace during the refining process. 6-8 tons, the LF furnace smelting time is more than 5 hours, which cannot meet the needs of continuous casting production

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