A process for manufacturing low-temperature molded tee by using x80 steel plate

Abstract

The invention discloses a technology for manufacturing a low-temperature mold pressing tee through an X80 steel plate. According to the technology, a tee pipe fitting is prepared through the X80 steelplate by combining a welding technology with a pressing forming technology, the grain size and strength loss allowances caused by multiple times of heating and long heating time in the machining process are increased, and the tee pipe fitting can be normally used for a long time in the -45 DEG C extremely cold weather. The tee pipe fitting prepared through the technology has the small grain size,high strength and low welding crack sensitivity coefficient, the homogeneity degree of all parts of the product is greatly improved, and the tee pipe fitting can be suitable for the -45 DEG C operating environment.

Description

technical field [0001] The invention relates to the technical field of processing tee pipe fittings, in particular to a process for manufacturing a low-temperature molded tee by using an X80 steel plate. Background technique [0002] In recent years, with the large demand for clean energy such as natural gas at home and abroad and strategic development and storage, long-distance pipeline projects are designed and constructed in the direction of large transmission capacity and low energy consumption. The use of high-grade steel, large-caliber, and high-pressure pipelines has become the development trend of long-distance pipeline construction. At the same time, the low temperature resistance of the pipeline material is improved, and the insulation and heat tracing facilities of the pipeline in the alpine region are removed. [0003] High-grade steel materials are prone to low-temperature brittle fracture in long-term bare pipe operation in extremely low-temperature environmen...

AI Technical Summary

Problems solved by technology

There are many quality risk points in the large-caliber seamed tee itself (due to the difference in wall thickness of the various parts of the large-caliber tee and the weld metal of high-grade steel products are sensitive to the thermal processing temperature, the strength and toughness are inversely proportional to the temperature change. and other technical bottlenecks), and according to the use characteristics of the tee, it is more complicated to be affected by factors such as installation stress, operating stress, and geological changes. It is necessary to ensure that the final overall quality state of the tee must accurately meet the requirements of engineering standards. The process and key nodes must be able to ensure the quality stability after mass production to ensure the safe operation of application engineering

[0004] In the patent CN108239720A, a method of using X80 steel grade plates to press tee pipe fittings is disclosed. The temperature of the press forming is 900-1000°C, and then it is quenched. The temperature of the quenching treatment is 930-1000°C, and finally tempered. The temperature of the tempering treatment is 580-650°C. The invention presses and forms the three-way pipe fittings, which causes problems such as large stress inside the pipe fittings and uneven structure of the pipe fittings, which shortens the service life of the three-way pipe fittings, resulting in Low product stability

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