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Heat treatment method for x80 elbow welded joints with excellent low temperature toughness

A heat treatment method and welding joint technology, applied in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve the problems of complex process, large environmental pollution, harsh operating environment, etc., and achieve simplified operation process, good tensile elongation, and simple effect of operation

Active Publication Date: 2021-09-10
XIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the main defects of the heat treatment technology of X80 elbow welded joints are: the quenching heating is usually heated to the quenching temperature at one time, the cooling method is oil cooling, the process is complex, the operating environment is harsh, and the environment is polluted. Therefore, it is necessary to further optimize the X80 elbow. Heat treatment process for pipe welded joints, thereby improving the overall low temperature mechanical properties of the bend

Method used

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  • Heat treatment method for x80 elbow welded joints with excellent low temperature toughness
  • Heat treatment method for x80 elbow welded joints with excellent low temperature toughness

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Step 1, choose X80 pipeline steel, the components according to mass percentage are as follows: C is 0.02%, Si is 0.1%, Mn is 1.25%, P is 0.018%, S is 0.004%, Nb is 0.04%, and Ti is 0.1% , Al is 0.18%, V is 0.10%, Ni is 0.10%, Mo is 0.15%, Cu is 0.2%; Cr is 0.02%, Bi is 0.005%, the balance is Fe, and the carbon equivalent Ceq is 0.31; using standard grades NS-2 submerged arc welding wire three-wire two-layer two-pass welding, the welding process temperature is 180°C, and the heat input is 30kJ / cm;

[0030] Step 2: Bending the straight-welded main pipe obtained by the submerged arc welding method with intermediate frequency induction overall heating, the normalizing heating temperature is 880°C, the advancing speed is 10mm / min, and the cooling method is air cooling to room temperature;

[0031] Step 3: Perform overall tempering treatment on the elbow welded joints obtained in step 2: the heating instrument is a box-type resistance furnace, the tempering temperature is 630...

Embodiment 2

[0033] Step 1, choose X80 pipeline steel, the composition according to mass percentage is as follows: C is 0.03%, Si is 0.2%, Mn is 1.58%, P is 0.016%, S is 0.002%, Nb is 0.07%, and Ti is 0.2% , Al is 0.2%, V is 0.18%, Ni is 0.2%, Mo is 0.19%, Cu is 0.1%; Cr is 0.01%, Bi is 0.004%, the balance is Fe, and the carbon equivalent Ceq is 0.35; the standard grade is adopted NS-2 submerged arc welding wire three-wire two-layer two-pass welding, the welding process temperature is 160°C, and the heat input is 33kJ / cm;

[0034] Step 2: Bending the straight-welded main pipe obtained by the submerged arc welding method with intermediate frequency induction overall heating, the normalizing heating temperature is 920°C, the advancing speed is 13mm / min, and the cooling method is air cooling to room temperature;

[0035] Step 3, conduct overall tempering treatment on the elbow welded joint obtained in step 2: the heating instrument is a box-type resistance furnace, the tempering temperature i...

Embodiment 3

[0037] Step 1, choose X80 pipeline steel, the components according to mass percentage are as follows: C is 0.04%, Si is 0.2%, Mn is 1.86%, P is 0.015%, S is 0.001%, Nb is 0.08%, and Ti is 0.2% , Al is 0.31%, V is 0.35%, Ni is 0.23%, Mo is 0.28%, Cu is 0.15%; Cr is 0.01%, Bi is 0.005%, the balance is Fe, and the carbon equivalent Ceq is 0.42; the standard grade is adopted NS-2 submerged arc welding wire three-wire two-layer two-pass welding, the welding process temperature is 120°C, and the heat input is 38kJ / cm;

[0038] Step 2: Bending the straight-welded main pipe obtained by the submerged arc welding method with intermediate frequency induction overall heating, the normalizing heating temperature is 940°C, the advancing speed is 16mm / min, and the cooling method is air cooling to room temperature;

[0039]Step 3, conduct overall tempering treatment on the elbow welded joint obtained in step 2: the heating instrument is a box-type resistance furnace, the tempering temperature...

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Abstract

The heat treatment method of the X80 elbow welded joint with excellent low-temperature toughness disclosed by the present invention, firstly, the X80 pipeline steel is welded with three wires, two layers and two passes with a standard submerged arc welding wire to obtain a straight seam welded joint; secondly, the obtained The welded joints of the straight seams are normalized in a high-temperature induction heating furnace, and the heat treatment is simultaneously bent and directly air-cooled to obtain the welded joints of the bent pipes; finally, the welded joints of the bent pipes obtained are placed in a box-type resistance furnace for another Heat treat and air cool to room temperature. The method disclosed by the invention is simpler and easier to operate than before, and the operation process is simplified, which greatly improves the reduction of the mechanical properties of the X80 elbow welded joint due to heat bending, and ensures that the low-temperature impact absorption energy of the X80 elbow is high and the tensile strength is high. Good elongation, high yield strength and high tensile strength and other comprehensive mechanical properties.

Description

technical field [0001] The invention belongs to the technical field of pipeline welding, and in particular relates to a heat treatment method for an X80 elbow welded joint with excellent low-temperature toughness. Background technique [0002] In recent years, China's West-East Gas Pipeline Second and Third Line Natural Gas Pipeline Project, Central Asia Natural Gas Pipeline Project, China-Russia Natural Gas Pipeline Project and Zhonggui Natural Gas Pipeline Project, the main lines all use X80 steel grade, and X80 pipelines have also been applied in foreign countries. . Elbows are widely used as a necessary structure to change the direction of pipelines. In the construction of oil and gas pipelines such as the West-to-East Gas Pipeline, China-Russia, and Central Asia, especially the China-Russia East Route project needs to pass through the extremely cold and permafrost regions, and the pipelines and elbows at some stations need to be exposed to low temperature environments....

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/50C21D1/18C21D1/28C21D6/00C22C38/02C22C38/04C22C38/06C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/58
CPCC21D1/18C21D1/28C21D6/004C21D6/005C21D6/008C21D9/505C22C38/002C22C38/02C22C38/04C22C38/06C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/58
Inventor 张敏李洁毕宗岳余唅张万鹏仝雄伟许帅
Owner XIAN UNIV OF TECH
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