SU1348122A1 - Flux for inert gas-shielded welding of alloys of light metals - Google Patents

Abstract

The invention relates to welding production, in particular to fluxes for welding aluminum alloys in inert gases. The aim of the invention is to improve the quality of welded joints in welding of alloys of the AMgb type due to the optimum ratio of strength and ductility. The introduction of scandium fluoride in the flux in the amount of 1-17 wt.% Provides hardening of the aluminum alloy with its high plasticity. The flux contains 15-16% aluminum fluoride, 18-20% calcium fluoride, 18-20% magnesium fluoride, and the rest lithium fluoride. 1 tab. i (L 00 x with fo

Description

The invention relates to welding production, in particular, to flux-arc arc welding, preferably in an inert gas environment with a non-consumable electrode of aluminum alloys.

The purpose of the invention is to improve the quality of welded joints from AMGB alloy due to the optimum ratio of strength and ductility.

Welded joints for comparative studies were obtained by ArDES with a non-consumable W electrode without filler wire from AMGB alloy plates. Welding mode parameters are as follows: welding current 155-160 A; welding speed 20 m / h; arc voltage 12-14 V; plate thickness 3.0 mm; argon consumption 8-10 l / min.

The properties of welded joints were evaluated by several indicators: the total pore volume in the weld metal in the initial state and after the thermal sample (potential gas supply); the number of oxide inclusions on the regulated length of the psh; maximum bending angle before cracking; temporary resistance of the welded joint. The results of comparative tests of welded joints are given in the table.

As follows from the table, the optimum content of fluoride scandium in the flux in terms of maximum bending angle and minimum porosity of the weld metal is 1-7 wt.%. The introduction of scandium fluoride into the flux to 17 wt.% Leads to an increase in the strength properties of the weld metal.

Scandium has a favorable size factor close in value to the size factor of manganese and zirconium - the most effective anti-crystallizers in aluminum. The hardening of alloys of aluminum with scandium is achieved through the processes of dispersion hardening with the separation of dispersed coherent particles of the ScAlj phase. The particles of the scandium phase are evenly distributed throughout the volume of subgrains, have a spherical (shape and small size of precipitates, structural and dimensional matching of the matrix and phase. The presence of such a phase leads to an increase in the mechanical properties of the weld metal. reduction of the plastic properties of the metal of the psh. This is determined by the presence of the process of enlargement of the particles of the ScAl.j phase (more than 0.15% scandium in the metal).

The use of flux, which includes scandium fluoride, leads to a decrease in the value of porosity, in addition, the potential reserve of gases in the weld metal is significantly reduced. The presence of this effect is associated with the positive effect of scandium on the increase in the solubility limit of hydrogen in the solid solution of the weld metal.

Along with a decrease in porosity, the mechanical properties of the weld metal change. With an increase in the content of fluoride, scandium in the flux increases with a temporary resistance to rupture. weld metal. Fractographic studies of fracture weld metal showed the dependence of the nature of the fracture on the content of fluoride scandium in the flux:

1-7 wt.% - viscous cellular destruction;

up to 17 wt.% - quasi-viscous destruction (in the fracture there are cells and cleavage facets); more than 17 wt.% - chipped - brittle

destruction.

Aluminum-magnesium alloys with a magnesium content of more than 3% are prone to intergranular corrosion. Corrosion occurs when the phase separating from the supersaturated solid solution is located at the grain boundaries in the form of a continuous chain, since the AljMgj compound is less neutral than the eL solid solution, it is first of all dissolved. If the phases of the AljMgj phase are distant from each other, then only local etching occurs. When fluoride scandium is introduced into the flux, the conditions of crystallization of the weld metal change. The boundary distributions of the jb-phase exist as separate globules. Therefore, the introduction of fluoride scandium makes the weld metal insensitive to intergranular corrosion.

Thus, the use of the proposed composition of the flux, as compared with the known, allows to reduce the porosity in the weld metal from 0.14 to 0.05 cm / 100 g I, to reduce the potential of I348I22

 the social gas supply from 0.29 to 0.13 g IU, exclude oxide inclusions in the weld metal, and also significantly improve the mechanical properties of the welded joint.

five

Claims (2)

Invention Formula ten Flux for welding alloys of light metals in inert gases containing lithium fluoride, aluminum fluoride, calcium fluoride, magnesium fluoride. The effect of the content of components in the proposed flux on the properties welded joints Calcium fluoride 18Fluoride magnesium 18Fluoride 1 Lithium fluoride Ost Note. I. „Alcohol 5% suspension was applied on the ends and root surface of joined edges. 2. The table shows the average results of testing five welds.  Order 5150/13 Circulation 969 Subscription Proiv polygr. pr-tie, Uzhgorod, st. Project, 4 It is distinguished by the fact that, in order to improve the quality of welded joints from the AMgb alloy, due to the optimum ratio of strength and ductility, the flux additionally contains scandium fluoride in the following ratio of components, May.%: Aluminum fluoride 15-16 Calcium fluoride 1820 Magnesium fluoride 1820 Fluoride scandium 117 Fluoride lithium Else