Welding wire commonly used for high strength-toughness magnesium alloy and preparation method of welding wire

Abstract

The invention relates to a welding wire commonly used for high strength-toughness magnesium alloy and a preparation method of the welding wire. The chemical components in the welding wire comprise, by weight, 1.4-2.7% of Al, 0.53-0.72% of Zn, less than 0.1% of Si, less than 0.05% of Fe, less than 0.1% of Ca, less than 0.1% of Cu, 0.04-0.1% of Be, less than 0.2% of Mn, 0.05-0.35% of Sr, and the balance magnesium and unavoidable impurity elements. A proper amount of Be and Sr are contained in the welding wire, the crystal grain structure of the welding wire is changed, so that the strength and the toughness of the magnesium alloy on the welding part are improved while crystal grains are finer, and meanwhile, the welding wire is suitable for the welding work of the magnesium alloy of multiple types.

Description

technical field [0001] The invention belongs to the field of welding technology, and in particular relates to a high-strength and toughness magnesium alloy universal welding wire and a preparation method thereof. Background technique [0002] Magnesium alloy welding wire is used to solve the application of various deformed magnesium alloys and cast magnesium alloys in maintenance. It is mostly used in kitchen utensils, auto parts, bicycles, aerospace and other fields. At present, the problems that are prone to occur in the welding of magnesium alloys: 1. Coarse grain: the melting point of magnesium is only 651°C, and the heat conduction is fast. When welding, a high-power heat source is used, so the weld and the metal in the heat-affected zone are prone to overheating and grain growth; 2. Oxidation and evaporation: Magnesium is extremely oxidizing, and it is easy to produce magnesium oxide at high welding temperatures. The melting point of magnesium oxide is as high as 2500 ...

AI Technical Summary

Problems solved by technology

At present, the problems that are prone to occur in the welding of magnesium alloys: 1. Coarse grain: the melting point of magnesium is only 651°C, and the heat conduction is fast. When welding, a high-power heat source is used, so the weld and the metal in the heat-affected zone are prone to overheating and grain growth; 2. Oxidation and evaporation: Magnesium is extremely oxidizing, and it is easy to produce magnesium oxide at high welding temperatures. The melting point of magnesium oxide is as high as 2500 ° C, and the density is high (3.2g / cm 3 ) It is easy to form fine flake solid slag inclusions in the molten pool. At high temperatures, magnesium is also easy to form magnesium nitrides with nitrogen in the air, which deteriorates the joint performance; 3. Thermal stress: magnesium and magnesium alloy wire The expansion coefficient is about twice that of steel (1.2 times that of aluminum), so greater thermal stress is generated during welding, which increases the tendency to crack; 4. Porosity: The solubility of hydrogen in magnesium decreases sharply as the temperature decreases, so Pores are prone to occur in the weld seam

The content of Al in this patent is higher than that in AZ31B. During the welding process, the volatilization of Mg will further increase the content of Al, resulting in insufficient metal strength of the welding part. At the same time, the welding wire of this patent can only weld one brand of magnesium alloy, and cannot Realize pass welding