Metal material, process and product for welding LNG ultralow-temperature stainless steel

A welding process and metal material technology, applied in the field of welding and manufacturing of LNG stainless steel equipment and pipelines, can solve the problems of rapid heat dissipation of stainless steel, poor thermal conductivity of stainless steel, and little practical value, and achieve the elimination of welding residual stress and welding efficiency The effect of improving and improving welding efficiency

Inactive Publication Date: 2019-12-17
WUHAN RUNZHIDA PETROCHEM EQUIP CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These low-melting oxidative inclusions will dissolve at high temperature, resulting in a significant decrease in weld strength, and will also cause weld tearing under the action of stress relaxation
[0007] 3. Negative effects of excessive welding stress:
[0009] Patent: A combined welding method for austenitic stainless steel medium and thick plates (201510292541.0), which proposes a welding method using copper plate water-cooled heat conduction to solve the problem of poor thermal conductivity of stainless steel, but it is not practical. For thick-walled equipment with a thickness of 20mm or more It is difficult to solve the problem of rapid heat dissipation of stainless steel by using copper plate heat conduction, and the practical value is not great

Method used

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  • Metal material, process and product for welding LNG ultralow-temperature stainless steel
  • Metal material, process and product for welding LNG ultralow-temperature stainless steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0065] 304L pipe butt welding, pipe diameter 450mm, wall thickness 25mm.

[0066] Groove angle: unilateral 15-35°, groove type U-shaped or V-shaped, blunt edge: 1-3mm, pair gap 3.0 ±1.0 . The bevel angle and the size of the blunt edge that meet the process requirements are machined by mechanical methods.

[0067] Self-shielded argon arc welding + twist welding wire argon arc welding: self-shielding solid argon arc welding wire is used as a primer, and argon arc welding twist welding wire is used for filling and covering.

[0068] Welding consumable composition is designed for pure austenitic stainless steel composition with ferrite content basically 0, and its composition formula is:

[0069] C: 0.03%, Cr: 18.1%, Si: 0.5%, Ni: 13%, Mn: 4.3%, N: 0.15%, S: 0.002%, P: 0.030%, Sr: 0.005.

[0070] After assembly, root the root for backing welding The self-shielded argon arc welding wire is used for welding to ensure that the back of the root bead is not over-oxidized. The weld...

Embodiment 2

[0074] S30403 stainless steel equipment steel plate coiled butt welding, equipment diameter 1800mm, circular seam and longitudinal seam welding, material wall thickness 16mm.

[0075] Use argon arc welding twist welding wire to make the bottom + submerged arc welding to fill and cover the surface.

[0076] The groove type is U-shaped, V-shaped or X-shaped groove, the thickness of the blunt edge is 1.0-2.0, and the gap between groups is 2.5 ±1.0 .

[0077] with diameter Twist welding wire argon arc welding as the base, and then use The submerged arc welding twist wire is filled until the cover welding is completed. After the back weld bead is cleaned with a special stainless steel grinder or a steel brush, it is filled with argon arc welding twist welding wire or submerged arc welding twist welding wire.

[0078] Welding consumables are pure austenitic stainless steel components with a designed ferrite content of basically 0, and the composition formula is:

[0079] C: 0...

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Abstract

The invention provides a metal material process and product for welding LNG ultralow-temperature stainless steel. The components and structure of a welding material are designed to make sure that thecontent of ferrite in a weld joint is low and the proportion of residual ferrite is reduced to be equal to or less than 1.0%; during welding, a stainless steel twisted welding wire is adopted, argon arc welding is adopted for bottoming, face filling is achieved through argon arc welding or submerged arc welding, the process parameters for welding are controlled to make sure that the energy of thewelding wire is equal to or less than 13KJ/cm, and meanwhile, the formula of a welding protective gas is set; and high-frequency vibration is conducted to assisting in welding to optimize the weldingquality. By the adoption of the metal material process and product for welding the LNG ultralow-temperature stainless steel, the plasticity and tenacity of weld joint metal are obviously improved, welding residual stress is greatly reduced, and the welding efficiency is improved.

Description

technical field [0001] The invention belongs to the welding manufacturing field of LNG stainless steel equipment and pipelines. Background technique [0002] Due to the large expansion coefficient and low thermal conductivity of austenitic stainless steel materials, the weld performance of austenitic stainless steel LNG equipment is difficult to meet the ultra-low temperature impact requirements. The reason is that there are the following factors: [0003] 1. Negative effects of residual ferrite in weld metal: [0004] According to the existing conventional theory, there are usually 4 to 10% ferrite in the weld metal of austenitic stainless steel, and there are similar expressions or requirements in some technical documents, and some require the residual ferrite to be 4 ~10%, some require 3~12%. Because the residual ferrite in the weld metal will bring about successive changes in the crystallization mode, so that welding hot cracks will not occur during welding, so the in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/30B23K35/40B23K35/02B23K9/16B23K9/18
CPCB23K9/16B23K9/18B23K35/0261B23K35/3086B23K35/40
Inventor 束润涛
Owner WUHAN RUNZHIDA PETROCHEM EQUIP CO LTD
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