Rare-earth-containing wet H2S corrosion resisting steel pipe used in heat exchanger, and production method thereof

Abstract

The invention discloses a rare-earth-containing wet H2S corrosion resisting steel pipe used in a heat exchanger, and a production method thereof. The invention belongs to the technical field of metallurgy and molding. The steel pipe is prepared from raw materials of, by weight: 90% of blast furnace molten iron and 10% of high-quality scrap steel. A tube blank comprises chemical components of, by weight: 0.03-0.10% of C; 0.10-0.30% of Si; 0.30-0.80% of Mn; no more than 0.014% of P; no more than 0.004% of S; 0.30-0.80% of Cr, 0.10-0.30% of Mo; 0.01-0.05% of Nb; 0.01-0.03% of Ti; 0.01-0.04% of Al, 0.0005-0.0100% of RE, less than 0.10% of Cu, and balance of Fe and undetectable trace elements. The technological process comprises steps of: molten iron pre-treating, smelting, refining, vacuum treating, continuous casting, heating, rolling, perforating, dogging, acid cleaning, phosphorizing, saponifying, cold drawing, heat treating, straightening, nondestructive testing, cutting, and packaging. Mechanical properties of the steel pipe are that: the yield strength is no less than 290MPa, the residual stress is no larger than 60MPa, the impact value is no less than 100J / cm<2>, and the grain size is no less than Grade 8. The product provided by the invention is characterized by high impact toughness, small grain size, and wet H2S corrosion resistance.

Description

1. Technical field: [0001] The invention belongs to the field of ferrous metal smelting and metal pressure processing, and relates to a rare earth-containing steel pipe for a moisture-resistant H2S corrosion heat exchanger and a production method thereof. 2. Background technology: [0002] With the development of my country's national economy, the demand for petroleum products is increasing day by day, and the number of domestically processed imported high-sulfur crude oil is also increasing year by year. The problem of low-temperature, medium-temperature and high-temperature corrosion caused by processing high-sulfur crude oil to equipment is becoming more and more serious, especially low-temperature vulcanization Hydrogen corrosion is a localized destruction of materials, which is more difficult to detect and prevent. Low-temperature wet hydrogen sulfide corrosion mainly includes three damage types: stress corrosion (SSC), hydrogen-induced cracking (HIC) and stress-oriented...

AI Technical Summary

Problems solved by technology

This is a problem that cannot be overcome by the electric furnace production process using scrap steel as raw material, because scrap steel inevitably contains harmful residual elements such as Cu, which cannot be removed during the steelmaking process, causing hydrogen sulfide to occur in the heat exchanger tubes during use. increased risk of corrosion cracking;

[0005] 2. The smelting and rolling process is more difficult

Although the Cr element is good for hydrogen sulfide corrosion resistance, its high content (2.0-2.5%) will cause certain difficulties in the smelting and rolling process. At the same time, the thermal conductivity of Cr is low, and the steel is heated or cooled due to thermal stress effect and easily lead to cracking;

[0006] 3. The content of Al element is relatively high (0.30-0.70%). Although Al element is beneficial to hydrogen sulfide corrosion resistance to a certain extent, its high content will increase the content of inclusions, thereby increasing the risk of hydrogen sulfide corrosion cracking

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