Copper-aluminium joint containing canine-shaped columnar crystal structure and preparation method thereof

Abstract

The invention relates to a copper-aluminium joint containing a canine-shaped columnar crystal structure and a preparation method thereof. The copper-aluminium joint comprises a copper tube and an aluminium tube, and is characterized in that a welding surface is formed by the aluminium tube, a canine-shaped columnar crystal and the copper tube, and the canine-shaped columnar crystal has the component of CuA12. During welding, the surface roughness Ra of the welding part on the outer surface of the copper tube is ranged from 0.4 Mu to 0.1 Mu, burrs on the end surface of the aluminium tube are controlled between 0.0 mm and 0.05 mm, the welding temperature is ranged from 647 DEG C to 665 DEG C, the current density is ranged from 475 A / mm<2>to 515 A / mm2, the pressure of an electrode air cylinder is ranged from 0.6 MPa to 0.8 MPa, the promoting pressure of a float electrode group is ranged from 0.6 MPa to 0.8 MPa, the applied pressure intensity in the copper tube is ranged from 800 kgf / cm to 1000 kgf / cm<2>, and the welding time is ranged from 0.6 S to 0.8 S. According to the copper-aluminium joint produced by the invention, because lamellar type alpha-A1+CuA12 in the joint is eliminated to form a single canine-shaped columnar crystal tissue, the mechanical property of materials is greatly enhanced, and the copper-aluminium joint has excellent heat-shock resistance, longer fatigue life, higher creep resistance and the comprehensive properties of the medium-temperature plasticity.

Description

technical field [0001] The invention relates to a welding joint of dissimilar metals, in particular to a thin-wall plug-in type copper-aluminum pipe welding joint. [0002] The invention also relates to a method for the preparation of the above-mentioned welded joint. Background technique [0003] The copper tube is composed of electrolytic copper, which has a large number of applications in production and life. Since the electrolytic copper is close to depletion, copper-aluminum welded tubes that share copper and aluminum instead of copper tubes have recently become a technical hotspot. Plug-in copper-aluminum tube resistance welding technology is the best solution for large-scale production. [0004] Copper-aluminum joints whose welding surface can withstand tensile stress are high-quality joints. However, some copper-aluminum joint welds cannot withstand tensile stress, and the prior art has not given a scientific explanation for it, so it has not been able to provide g...

AI Technical Summary

Problems solved by technology

However, some copper-aluminum joint welds cannot withstand tensile stress, and the existing technology has not given a scientific explanation for it, so it has not given guidance on how to increase the tensile stress of copper-aluminum joints.

This is because there is no correct understanding of the microstructure of the welded joints, and the direction of the technology is not clear enough to ensure that the copper-aluminum joints form a unified microstructure. Further innovations in the copper-aluminum welding method are needed to obtain high-quality and low-cost products. The product

The inventor found through research that there is lamellar α-Al+CuAl in the weld seam of the copper-aluminum joint 2 , is the main reason why copper-aluminum joints cannot withstand tensile stress

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