22Cr duplex phase stainless tube welding method

Abstract

The invention relates to a welding method of 22Cr duplex stainless steel corrosion resistant alloy pipe, which adopts a gas mixture of 99.995 percent pure Ar and 98 to 99 percent Ar plus 2 percent N2 or a gas mixture of 90 to 95 percent of N2 plus 5 to 10 percent H2 to weld the two laterals within the range equal to or more than 100mm inside the pipe; back welding, fill welding and cap welding are implemented when the oxygen content is equal to or less than 50ppm; the welding and filling metal deposit includes the following components according to the weight percentage: C is equal to or less than 0.04, Cr is 22.0 to 23.5, Ni is 8.5 to 10.5, Mo is 3.0 to 3.5, Mn is 0.5 to 2.0, Si is equal to or less than 0.9, P is equal to or less than 0.04, S is equal to or less than 0.03, N is 0.15 to 0.20 and Cu is equal to or less than 0.75. A balanced austenitic-ferritic microstructure is obtained with good joint tensility and low-temperature shock toughness, as well as good corrosion performances of anti-pitting corrosion of chloride, stress corrosion and simulated environment medium corrosion resistance.

Description

technical field [0001] The invention relates to a welding method for a 22Cr (also called 2205) duplex stainless steel corrosion-resistant alloy pipeline. Background technique [0002] Pipeline transportation is a safe, economical and uninterrupted large-scale transportation of oil and gas. Pipelines are widely used in industrial fields such as oil and gas transportation and chemical industry. Many pipelines require corrosion-resistant materials due to corrosion requirements. Duplex stainless steel began to be used in engineering in the 1930s, but it has not been used on a large scale due to problems such as materials and welding. Until the 1970s, with the advancement of metallurgical technology and the discovery of the important role of nitrogen in duplex stainless steel, the second generation of new nitrogen-containing duplex stainless steel was developed, and the weldability of the material was improved, so that duplex stainless steel began to be used abroad. It is widely...

AI Technical Summary

Problems solved by technology

Disadvantages of this technology: 1. Pure argon is used as the molten pool shielding gas for backing welding and heat welding (second layer) of this welding process, which may denitrify the welding molten pool at high temperature, so that the weld metal The nitrogen content is reduced, and this metal uses nitrogen as an alloying element, which plays a very important role in ensuring the structure and corrosion resistance; This method has poor weld formation, difficult operation and prone to welding defects

This method needs to add shielding gas when welding, and the welding quality is very sensitive to wind. It is difficult to ensure the welding quality in the field construction environment. In large cases, it may cause the welded joint to produce a microstructure with excessive ferrite content, which will affect the mechanical properties and corrosion resistance of the joint; According to the control requirements of the oxygen content on the back, serious oxidation may occur on the back of the joint, which will affect the corrosion resistance; 5. The welding process parameters give specific ranges of current, voltage, and welding speed, but there is no limit to the parameters of the welding line energy, and the line energy It is a very important parameter of the welding process. Only the range of current, voltage and welding speed can not guarantee that the parameters of the line energy meet the requirements; Process parameters used for other material thickness; 7. Even if the control is very strict, due to various factors, the inner weld and heat-affected zone in contact with the medium will inevitably have different degrees of oxidation, which will affect the corrosion resistance of the material. propose a solution

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