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A Method for Reducing Residual Stress in Brazed Joints

A technology of brazing joints and residual stress, applied in welding equipment, manufacturing tools, auxiliary devices, etc., can solve the problems of reducing the safe service life of structures, residual stress, geometric discontinuous temperature gradient, etc., to improve quality and reduce residual stress Effect

Active Publication Date: 2021-09-21
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Since brazing is to use solder to connect the base material, it belongs to the structure of dissimilar materials, and there are geometric discontinuities and temperature gradients, so it will cause large residual stress, seriously affect the mechanical properties of brazing materials, and greatly reduce the safety of the structure service life

Method used

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  • A Method for Reducing Residual Stress in Brazed Joints
  • A Method for Reducing Residual Stress in Brazed Joints

Examples

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Effect test

Embodiment 1

[0030] This embodiment is brazing of the same material, the base metal of the brazing joint is 316L, and the brazing filler metal is BNi-2.

[0031] (1) Pre-welding treatment: pre-weld the brazing sample, put it into a vacuum brazing furnace after assembly, and evacuate the furnace to 5×10 -3 Pa; the specific processing steps are as follows:

[0032] ①Clean the base metal: Pickle the base metal, boil it with 5% NaOH lye, wash it with hot water, and finally wash it with acetone and dry it and seal it for storage. ②Clean the brazing filler metal: cut the brazing filler metal according to the size, clean it with acetone and seal it for storage. ③ Brazing surface preparation: Grinding and polishing the brazing surface of the base metal (mechanical grinding to 800# sandpaper), after polishing, boil the brazing metal base material with 5% NaOH lye, and then clean it with hot water and acetone respectively Dry and seal for later use. ④Preset solder: Assemble brazing parts. Preset...

Embodiment 2

[0041] The difference from Example 1 lies in the brazing of dissimilar materials: the base materials of the brazing joints are 316L and 304 stainless steel respectively, and the brazing filler metal is BNi-2.

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Abstract

The invention relates to the field of welding technology, in particular to a method for reducing residual stress in brazed joints. The method of the present invention comprises the steps of: heating the assembled base metal and solder to the brazing temperature for brazing to form a brazed joint; then naturally cooling the brazed component from the brazing temperature to 800 °C under vacuum °C; when cooled to 800 °C, fill with nitrogen to continue cooling to 600-700 °C, keep the temperature for 10-40 hours, and cool to room temperature after the heat preservation is over. By adopting the method of the invention, the residual stress in the brazing joint can be greatly reduced, and the quality of the brazing joint can be improved.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a method for reducing residual stress in brazed joints. Background technique [0002] Brazing connection technology is currently widely used in petrochemical, aerospace, nuclear power and fuel cells and other fields. Brazing technology uses a material with a lower melting point than the base metal as the solder, heats the weldment and the solder to an operating temperature higher than the liquidus of the solder but lower than the solidus of the base metal, and wets the base with the liquid solder. It is a welding technique that fills the gap between brazed joints and interdiffused with the base metal to realize the connection. Since brazing is to use solder to connect the base material, it belongs to the structure of dissimilar materials, and there are geometric discontinuities and temperature gradients, so it will cause large residual stress, seriously affect the mechanical pr...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23K1/008B23K3/08
CPCB23K1/008B23K3/085
Inventor 张玉财蒋文春涂善东张显程罗云
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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