CN111014864B

CN111014864B - Preparation method for joint with directional grain brazing seam through rapid ultrasonic-assisted manufacturing

Info

Publication number: CN111014864B
Application number: CN201911256462.9A
Authority: CN
Inventors: 丁敏; 王剑; 郝红; 冀志强; 席亚斌; 赵格龙
Original assignee: Taiyuan University of Technology
Current assignee: Taiyuan University of Technology
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2022-04-01
Anticipated expiration: 2039-12-10
Also published as: CN111014864A

Abstract

A method for manufacturing a joint with directional grain brazing seams by rapid ultrasonic assistance belongs to the technical field of brazing, and aims to provide a method for orienting the grain brazing seams. The strength of the aluminum alloy joint is higher than that of the aluminum alloy joint prepared by the existing method due to the directional structure, the process is simpler, and an intermediate layer is not needed.

Description

Preparation method for joint with directional grain brazing seam through rapid ultrasonic-assisted manufacturing

Technical Field

The invention belongs to the technical field of brazing, and particularly relates to a method for preparing a joint with directional grain brazing seams by means of rapid ultrasonic auxiliary manufacturing.

Background

During brazing, in the large gap, crystal grains can grow up without directionality, and the large crystal grains can influence the strength of the joint; when the small gap is adopted, a crystal grain layer is arranged along the width direction of the brazing seam, the gap is reduced, the amount of solidified metal is reduced, smooth plane crystal grains can be formed after solidification, and the strength of the welding seam is improved. However, how to make the crystal grains in the brazing seams have directionality is an urgent problem to be solved for improving the brazing strength of the aluminum alloy.

The ultrasonic-assisted brazing technology is characterized in that ultrasonic influence is applied in the brazing process, the ultrasonic can generate the action of cavitation and acoustic flow, the crystal grains can be refined, and the growth direction of the crystal grains is disturbed, so that the brazing seam cannot keep the complete directional growth of columnar crystals during solidification, and the microstructure and the mechanical property of a formed part are influenced.

Disclosure of Invention

The invention aims to provide a method for brazing seam grain orientation, in particular to an ultrasonic auxiliary welding method for low-temperature soft soldering of aluminum, which ensures that the interior of a joint molten pool always keeps positive temperature gradient along the X-axis direction in the brazing process, thereby ensuring that a columnar crystal structure in a formed piece continuously grows from a parent metal along the X-axis forming direction and ensuring that a formed brazing seam obtains a complete solidified columnar crystal structure.

The invention adopts the following technical scheme:

a method for preparing a joint with directional grain brazing seams by rapid ultrasonic-assisted manufacturing comprises the following steps:

firstly, putting SnZn eutectic solder into a quartz container for melting, and then adding multilayer graphene oxide and SiC micron particles;

secondly, keeping the temperature at 230-;

thirdly, heating the steel mould to 180-200 ℃, and casting the mixed solder in the quartz container into the steel mould;

fourthly, placing the steel mould filled with the mixed solder in a room temperature environment, and cooling to obtain the solder;

fifthly, placing the welding part of the aluminum alloy plate on a heating platform, placing 0.3-0.5g of solder on the welding part, keeping the gap between 0.03-0.1mm, applying 10-30N pressure at the welding temperature of 230-250 ℃, applying ultrasonic power of 300-500W, welding for 1-3s, and cooling to room temperature to obtain the brazing seam joint with the crystal grains oriented along the X axis of the base material.

In the first step, the multilayer graphene oxide accounts for 1-4% of the eutectic solder by mass, the thickness of the multilayer graphene oxide is 10-50nm, the SiC micron particles account for 1-4% of the eutectic solder by mass, and the size of the SiC micron particles is 10-50 um.

The invention has the following beneficial effects:

the invention discloses a preparation method of a joint with directional grain brazing seams by rapid ultrasonic-assisted manufacturing, which has the following beneficial effects: the surface of the aluminum joint prepared by the steps and the process is smooth and has good toughness. The melting temperature of the brazing filler metal is 180-195 ℃, the brazing temperature is 230-250 ℃, the method is good in manufacturability, the maximum joint strength can reach 90MPa, the strength is higher than that of an aluminum alloy joint prepared by the existing method due to the fact that the structure has directionality, the process is simpler, and an intermediate layer is not needed.

Drawings

FIG. 1 is a typical metallographic picture of a linker according to example 1 of the present invention.

Detailed Description

Example 1

Firstly, putting SnZn eutectic solder into a quartz container for melting, and then adding 4% of multilayer graphene oxide and 2% of SiC micron particles by mass ratio. The thickness of the multilayer graphene oxide is 10nm, and the size of SiC micron particles is 10 um.

And secondly, keeping the temperature at 230 ℃ and stirring uniformly, and then slowly cooling the quartz container to 180 ℃ at room temperature to prepare the mixed solder.

Step three, heating the steel die to 180 ℃ while performing the step two, and casting the mixed solder in the quartz container into the steel die;

and fourthly, placing the steel mould filled with the mixed solder in a room temperature environment for cooling to obtain the used solder.

Fifthly, placing the welding part of the aluminum alloy plate on a heating platform, placing 0.3g of solder on the welding part, keeping the gap between the welding part and the heating platform at 0.03mm, welding at 230 ℃, applying 20N pressure and ultrasonic power of 300W for 1s, and then cooling to room temperature to obtain the brazing seam joint with crystal grains oriented along the X axis of the base metal.

Example 2

Firstly, putting SnZn eutectic solder into a quartz container for melting, and then adding 1% of multilayer graphene oxide and 1% of SiC micron particles by mass ratio. The thickness of the multilayer graphene oxide is 30nm, and the size of SiC micron particles is 40 um.

And secondly, keeping the temperature at 250 ℃, uniformly stirring, and then slowly cooling the quartz container to 190 ℃ at room temperature to prepare the mixed solder.

Step three, heating the steel die to 190 ℃ while performing the step two, and casting the mixed solder in the quartz container into the steel die;

Fifthly, placing the welding part of the aluminum alloy plate on a heating platform, placing 0.4g of solder on the welding part, keeping the gap between 0.05mm, welding at 240 ℃, applying 30N pressure and 500W ultrasonic power, welding for 1s, and then cooling to room temperature to obtain the brazing seam joint with crystal grains oriented along the X axis of the base metal.

Example 3

Firstly, putting SnZn eutectic solder into a quartz container for melting, and then adding 3% of multilayer graphene oxide and 4% of SiC micron particles by mass ratio. The thickness of the multilayer graphene oxide is 50nm, and the size of SiC micron particles is 50 um.

And secondly, keeping the temperature at 300 ℃, uniformly stirring, and then slowly cooling the quartz container to 200 ℃ in a room temperature environment to prepare the mixed solder.

Fifthly, placing the welding part of the aluminum alloy plate on a heating platform, placing 0.5g of solder on the welding part, keeping the gap between 0.10mm, welding at 250 ℃, applying 20N pressure and 400W ultrasonic power, welding for 2s, and then cooling to room temperature to obtain the brazing seam joint with crystal grains oriented along the X axis of the base material.

Claims

1. A method for preparing a joint with directional grain brazing seams by rapid ultrasonic-assisted manufacturing is characterized by comprising the following steps of: the method comprises the following steps:

secondly, keeping the temperature at 230-;

fifthly, placing the welding part of the aluminum alloy plate on a heating platform, placing 0.3-0.5g of solder on the welding part, keeping the gap between 0.03-0.1mm, applying 10-30N pressure at the welding temperature of 230-;

in the first step, the mass fraction of the multilayer graphene oxide in the eutectic solder is 1-4%, the thickness of the multilayer graphene oxide is 10-50nm, the mass fraction of SiC micron particles in the eutectic solder is 1-4%, and the size of the SiC micron particles is 10-50 um.