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Non-protective bottoming welding technology with solid core welding wire for back of staniless steel pipe

A solid-core welding wire, welding technology, applied in welding media, welding equipment, welding equipment and other directions, can solve the problems affecting stainless steel tube fusion, arc migration, slag generation, etc., to reduce production costs, high weld pool visibility, Reduce the effect of preparation work

Inactive Publication Date: 2004-04-28
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The welding of stainless steel pipes usually consists of three parts: root welding, filling welding and cover welding. Among them, root welding is the most critical part in the welding of stainless steel pipes, and the problem of oxidation on the back of the weld has been difficult to solve satisfactorily.
However, due to the inherent characteristics of the flux-cored wire itself, this welding method also has certain defects: 1. Due to the fast melting speed of the flux-cored wire, the welder needs to send the wire to the correct position quickly and accurately, thus requiring the welder to have a high level of operation ; 2. When the flux-cored wire is grounding, slag will be produced. When the welder observes the molten pool, it is not as clear as the solid-cored wire, and it is difficult to judge the penetration of the back side.
3. Since the middle of the flux-cored wire is powder and the outer layer is steel skin, the arc burns around the steel skin during welding, which is easy to cause the migration of the arc, causing the arc to swing and affecting the fusion on both sides of the stainless steel pipe.
[0010] In addition, since this method produces slag on the back of the weld, it is not suitable for welding pure pipes (such as stainless steel pipes for the food industry)

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Embodiment 1: The mixed gas ratio is: the volume percentage of helium is 85%, the volume percentage of argon is 10%, and the volume percentage of carbon dioxide is 5%. Welding is carried out according to the following welding process parameters:

[0033] Welding current: 100A~120A Welding voltage: 15V~16V Gas flow: 12~15L / min

Embodiment 2

[0034] Embodiment 2: The mixed gas ratio is: the volume percentage of helium is 90%, the volume percentage of argon is 7%, and the volume percentage of carbon dioxide is 3%. Welding is carried out according to the following welding process parameters:

[0035] Welding current: 100A~120A Welding voltage: 15V~16V Gas flow: 12~15L / min

Embodiment 3

[0036] Embodiment 3: The mixed gas ratio is: the volume percentage of helium is 94%, the volume percentage of argon is 5%, and the volume percentage of carbon dioxide is 1%. Welding is carried out according to the following welding process parameters:

[0037] Welding current: 100A~120A Welding voltage: 15V~16V Gas flow: 12~15L / min

[0038] The base material is A316L, and its chemical composition is shown in Table 1. Welding groove and weld samples are selected according to GB4334.5-90.

[0039] The argon tungsten arc welding with argon protection on the back side (comparative example) uses ER316L welding wire, and the diameter of the welding wire is 2.4mm. The specific process parameters are: Welding current: 120A~130A Welding voltage 8V~10V Gas flow rate 10L / min~15L / min

[0040] Choose the example of the present invention to compare with the argon tungsten arc welding (comparative example) of back filling argon, and the specific implementation method is as follows:

[004...

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Abstract

The present invention belongs to the field of welding in material processing engineering, and is used mainly in welding austenic stainless steel in petroleum, chemical, medicine, ship building, food production and other fields. The present invention features that the solid core welding wire ER308L-Si or ER316L-Si is matched with the mixed gas of He 85-94 vol%, Ar 5-10 vol% and CO2 1-5 vol% for the bottoming welding. The present invention needs no back side protecting gas and this simplifies the preparation, lowers the cost and raises the production efficiency. The present invention is especially suitable for welding construction of large and long stainless steel, and in-situ overhead welding operation.

Description

technical field [0001] The invention belongs to the welding field of material processing engineering, and is mainly used for welding austenitic stainless steel in the fields of petroleum, chemical industry, medicine, shipbuilding, food and the like. Background technique [0002] The welding of stainless steel pipes usually consists of three parts: root welding, filling welding and cover welding. Among them, root welding is the most critical part in the welding of stainless steel pipes, and the problem of oxidation on the back of the weld has been difficult to solve satisfactorily. At present, there are two main types of stainless steel bottoming: the back is filled with protective gas and the back is not filled with protective gas. [0003] 1. The shielding gas on the back is mainly argon tungsten arc welding of solid wire (rod) [0004] This is the most widely used stainless steel pipe welding technology at present, suitable for welding stainless steel pipes with a diamete...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K9/16B23K31/12B23K35/22
Inventor 栗卓新李国栋魏琪蒋建敏
Owner BEIJING UNIV OF TECH
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