Method for producing non-quenched and tempered N80 petroleum tube by RH refining technology

Abstract

The invention relates to a method for producing a non-quenched and tempered N80 petroleum tube by a RH refining technology, comprising molten iron pretreatment, converter smelting, RH refining, round billet continuous casting and round billet rolling. The method is characterized in that high pressure nitrogen is used as big pot bottom gas and lift gas during the RH refining process so as to increase nitrogen content in molten steel. The technological process comprises the following steps of: 1) using high pressure nitrogen as lift gas during RH; 2) blowing high pressure nitrogen at the big pot bottom during the RH vacuum desulphurization process, and adjusting the flow to 1-2Nl / min.ton steel when the sulfur content is less than 0.010% through sampling analysis; 3) continuing to blow nitrogen at the big pot bottom to increase nitrogen after RH vacuum breakage. In comparison with the prior art, the invention has the following beneficial effects: 1) the traditional LF+VD+nitrogen-containing alloy production technology is replaced with the RH refining+nitrogen purging treatment process to simplify production link and reduce cost; 2) the content of nitrogen in steel is increased by nitrogen purging so as to save the hypervalent nitrogen-containing alloy usage.

Description

technical field [0001] The invention relates to a method for producing non-quenched and tempered N80 oil pipes by RH refining process. Background technique [0002] According to the requirements of API standards, N80 oil pipes have strict requirements on sulfur and phosphorus, and other components are aimed at achieving mechanical performance indicators. Therefore, the composition design and production process adopted by each steel factory are different. Among them, increasing the nitrogen content in steel There are more billets produced by this method. [0003] Publication number CN101020986A introduces a production process of N80, its chemical composition (wt%) C: 0.34-0.38, Si: 0.25-0.35, Mn: 1.65-1.85, V: 0.08-0.12, N: 0.013-0.0145, Ti: 0.05 ~0.025, Al: 0.02~0.05, using nitrogen-vanadium alloy to increase nitrogen. [0004] Publication number CN1940368A introduces a kind of N80 production process, its chemical composition (wt%) C: 0.32~0.42, Si: 0.2~0.7, Mn: 1.2~1.65, ...

AI Technical Summary

Problems solved by technology

[0006] The above existing technologies all adopt the method of steel nitrogen fixation based on the composition design, but the nitrogen-vanadium alloy is used to increase the price of nitrogen, and the process of using LF+VD has many links, which is not conducive to cost reduction.

Since N80 has a limitation on sulfur content, it is generally required to be less than 0.010%, and the RH of most steel plants does not have the desulfurization function, so LF desulfurization is required, so RH is not used alone to produce N80