A sintered flux suitable for submerged arc welding of x70ms corrosion-resistant pipeline steel pipe

Abstract

The invention discloses a sintered flux suitable for X70MS anti-corrosion pipeline steel tube submerged arc welding. The flux comprises rare earth silicon-magnesium alloy, wherein rare earth magnesium-silicon is greater than or equal to 1 and less than or equal to 10 according to the mass percent. According to the mass percent, the flux comprises the following ingredients of CaF2 greater than or equal to 20 and less than or equal to 25, MgO greater than or equal to 20 and less than or equal to 30, Al2O3 greater than or equal to 10 and less than or equal to 20, CaO greater than or equal to 5 and less than or equal to 10, MnO greater than or equal to 1 and less than or equal to 3, SiO2 greater than or equal to 20 and less than or equal to 25, Mn-Fe greater than or equal to 1 and less than or equal to 5, Si-Fe greater than or equal to 1 and less than or equal to 4, the rare earth magnesium silicon is greater than or equal to 1 and less than or equal to 10, S less than or equal to 0.01, and P less than or equal to 0.02. Based on strict control on the materials P and S, a weld seam is ensured to have good processing property and higher degree of purity, and in a metallurgical reaction process, harmful impurities such as P and S are removed as far as possible, a higher alkalinity is adopted, and C and Mn are strictly controlled, so that the smooth transition of alloy easily damaged by burning, such as Cr and Mo is ensured. The weld seam is enabled to have good mechanical property and certain H2S corrosion resistance.

Description

Technical field [0001] The present invention is aimed at containing H 2 S corrosive medium natural gas pipeline oil and gas transmission application requirements, develop a suitable for X70MS H-resistant 2 S is a flux for welding corrosion pipeline steel. Using the flux of the present invention, matching the corresponding welding wire and X70 H resistant 2 After the S corrosion pipeline steel is welded, it can have good resistance to H while ensuring the excellent impact toughness of the weld. 2 S corrosion performance. Background technique [0002] In recent years, with the continuous extension of oil and gas exploration distances, long-distance, special environment and media transportation of oil and gas has become the main trend of future development. my country has abundant marine oil and gas reserves, good prospects for exploration, and huge development potential. With the acceleration of the development of the offshore oil and gas industry, the status of the offshore oil an...

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Problems solved by technology

Therefore, the development of deep-sea pipelines will be the development trend of long-distance pipelines in the future. However, the pipelines are located on the seabed, and most of them need to be buried at a certain depth in the seabed soil. The pipeline corrosion is caused by the transformation of the metal element state into an ion state under the combined action of the chemical or electrochemical action of the surrounding medium and chemical factors or biological factors on the surface of the pipeline metal material.

In recent years, the scale of oil and gas exploration in my country has become larger and larger. The harsh environment of high hydrogen sulfide content and alpine regions has put forward higher requirements for pipeline transportation and storage. The requirements are getting higher and higher. In order to avoid the increase of FeS and MnS content in the weld due to the sulfur content in the base metal and welding materials, which will cause stress corrosion cracking of the weld, ensure that the weld due to S - 、H + Penetrating into the steel to cause stress corrosion cracks requires welds with lower hardness, equal-strength or low-strength matching and higher cleanliness, while the flux used for ordinary pipeline steel mainly focuses on the strength and toughness of the welds, and does not have Considering the corrosion problem, it is necessary to develop a H-resistant 2 S and seawater corrosion flux

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