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Method for reducing residual stress in brazed joint

A technology for brazing joints and residual stress, applied in welding equipment, auxiliary devices, metal processing equipment, etc., can solve problems such as residual stress, geometrically discontinuous temperature gradient, and reduce the safe service life of structures

Active Publication Date: 2020-11-06
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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  • Method for reducing residual stress in brazed joint
  • Method for reducing residual stress in brazed joint

Examples

Experimental program
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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 technical field of welding, in particular to a method for reducing residual stress in a brazed joint. The method comprises the following steps: heating assembled base metal and brazing filler metal to a brazing temperature for brazing to form the brazed joint; then naturally cooling a brazed member from the brazing temperature to 800 DEG C under the vacuum condition; when the temperature is cooled to 800 DEG C, introducing nitrogen for continue cooling to 600-700 DEG C, performing thermal insulation for 10-40 hours, and then performing cooling to room temperature after thermal insulation. The method can greatly reduce the residual stress in the brazed joint and improve quality of the brazed joint.

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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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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