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Method for improving mechanical property of FSW (friction stir welding) magnesium alloy joint

A friction stir and magnesium alloy technology, which is applied in welding equipment, non-electric welding equipment, metal processing equipment, etc., can solve the problems of reducing the mechanical properties of magnesium alloy friction stir welding joints and low joint strength, and achieves easy promotion, low cost, The method is simple and effective

Inactive Publication Date: 2012-07-04
CHONGQING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The joint strength of friction stir welded magnesium alloys, especially magnesium alloys with forged structures, is generally lower than that of the magnesium alloy base metal. One of the important reasons is that it is easy to form a specific grain orientation during friction stir welding. This orientation facilitates slip cracking during the stress process, thereby reducing the mechanical properties of friction stir welded joints in magnesium alloys

Method used

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  • Method for improving mechanical property of FSW (friction stir welding) magnesium alloy joint
  • Method for improving mechanical property of FSW (friction stir welding) magnesium alloy joint
  • Method for improving mechanical property of FSW (friction stir welding) magnesium alloy joint

Examples

Experimental program
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Effect test

Embodiment 1

[0034] Select the AZ31 magnesium alloy plate 1 after rolling and finishing the grain orientation, the angle between its grain orientation and the horizontal plane of the magnesium alloy plate is 90 degrees, and the cut magnesium alloy plate 1 and the horizontal plane are 0 degrees, and the AZ31 magnesium alloy plate is obtained 2. Two pieces of AZ31 magnesium alloy plates 2 with a thickness of 6.0 mm were welded in a butt joint manner by friction stir welding. The diameter of the shoulder is 15 mm, the diameter of the stirring pin is 5 mm, the length is 5.7 mm, and the welding speed is 600 mm / min. The stirring head rotation speed was 1600 rpm. After testing, the welded magnesium alloy plate joints obtain a maximum tensile strength of 241Mpa, which is almost as strong as the base metal (243Mpa). The fracture occurs in the base material, and the welding bonding efficiency is 100%. The maximum elongation is 20.5%, which is less than the maximum elongation of the base metal, which...

Embodiment 2

[0036] Select the AZ31 magnesium alloy plate 1 after rolling and finishing the grain orientation, the angle between its grain orientation and the horizontal plane of the magnesium alloy plate is 90 degrees, and the angle between the cut magnesium alloy plate 1 and the horizontal plane is 45 degrees, and the AZ31 magnesium alloy plate is obtained 2. Two pieces of AZ31 magnesium alloy plates 2 with a thickness of 6.0 mm were welded in a butt joint manner by friction stir welding. The diameter of the shoulder is 15 mm, the diameter of the stirring pin is 5 mm, and the length is 5.7 mm. The welding speed is 600 mm / min, and the rotation speed of the stirring head is 1600 rpm. After testing, the maximum tensile strength obtained by the welded magnesium alloy plate joint is 212 Mpa, which is greater than the strength of the base metal (204 Mpa), the fracture occurs in the base metal, and the welding bonding efficiency is 100%. The maximum elongation is 35.5%, which is slightly lower ...

Embodiment 3

[0038] Select the AZ31 magnesium alloy plate 1 after rolling and finishing the grain orientation, the angle between its grain orientation and the horizontal plane of the magnesium alloy plate is 90 degrees, and the cut magnesium alloy plate 1 and the horizontal plane are 90 degrees, and the AZ31 magnesium alloy plate is obtained 2. Two pieces of AZ31 magnesium alloy plates 2 with a thickness of 6.0 mm were welded in a butt-joint manner by the friction stir welding method. The diameter of the shoulder is 15 mm, the diameter of the stirring pin is 5 mm, and the length is 5.7 mm. The welding speed is 600 mm / min, and the rotation speed of the stirring head is 1600 rpm. After testing, the maximum tensile strength obtained by the welded magnesium alloy sheet joint is 245 Mpa, which is slightly lower than the base metal strength (265 Mpa). The fracture occurs at the junction of the stirring zone and the thermomechanical affected zone on the forward side of the joint, and the welding b...

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Abstract

The invention discloses a method for improving the mechanical property of an FSW (friction stir welding) magnesium alloy joint. The method comprises the steps as follows: 1), a magnesium alloy plate is taken and is rolled, compressed or forged until the grain orientations in the magnesium alloy plate are consistent, and the grain orientations in the magnesium alloy plate is detected through X-Ray Diffraction (XRD) or backscattered-electron diffraction (BSED) to obtain a magnesium alloy plate 1 of which the grain orientation is trimmed; 2), the magnesium alloy plate 1 is cut to obtain magnesium alloy plates 2 of which the grain orientations form included angles with the horizontal surface of the magnesium alloy plate respectively; and 3), and the two magnesium alloy plates 2 are butt-welded in an FSW method to obtain a magnesium alloy FSW joint with an excellent mechanical property. According to the method, before FSW, the grain orientation of the transition area of the joint is improved by adjusting the initial grain orientation of magnesium alloy, so that the mechanical property of the magnesium alloy joint is improved greatly, and the strength of the joint is close to that of base metal to ensure the application of magnesium alloy FSW piece.

Description

technical field [0001] The patent of the invention belongs to the field of welding technology, and in particular relates to a method for improving the mechanical properties of friction stir welded magnesium alloy joints by adjusting the initial grain orientation. Background technique [0002] Friction stir welding (FSW) is a solid-phase joining technology patent invented by the British Welding Institute in 1991. The method is to insert a specific-shaped stirring needle into the seam of the workpiece to be welded, and rotate the stirring head at high speed to make the shaft The friction between the shoulder and the stirring needle and the workpiece to be welded generates heat, so that the temperature of the material at the welded part rises and softens to a thermoplastic state, and the welded material in the thermoplastic state near the seam undergoes plastic flow under the rotating stirring of the stirring needle, and along the Relative movement occurs in the welding directi...

Claims

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Application Information

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IPC IPC(8): B23K20/12B23K20/233B23K20/24
Inventor 辛仁龙刘德佳李波刘庆周正
Owner CHONGQING UNIV
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