RU2393073C1 - Aluminium based welding wire composition - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to metallurgy of aluminium based alloys, particularly to welding materials designed for making welding wire for fuse welding structures from deformable non-heat-treatable alloy of the Al-Mg-Sc system. The alloy contains the following in wt %: magnesium 5.5-6.5; manganese 0.50-0.80; scandium 0.25-0.35; zirconium 0.10-0.20; titanium 0.02-0.05; chromium 0.10-0.20; vanadium 0.005-0.04; cerium 0.01-0.05; boron 0.004-0.01; beryllium 0.002-0.005; aluminium - the rest, where Mn+Sc+Ti+Zr=0.95-1.3. ^ EFFECT: higher strength and plasticity of weld metal and weld joint from non-heat treatable aluminium alloy, sparingly doped with scandium. ^ 2 tbl, 1 ex

Description

The invention relates to the field of metallurgy of aluminum-based alloys, in particular to welding materials, is intended for the manufacture of a welding wire for fusion welding of structures from a deformable thermally unreinforced economically alloyed with scandium alloy system Al-Mg-Sc in various fields of technology: shipbuilding, aerospace industry, etc.

Currently, there are a number of deformable thermally non-hardening alloys of the aluminum-magnesium-scandium system used for the manufacture of aluminum welding wire. Known deformable thermally unstrengthened alloy based on aluminum for fusion welding (RF patent No. 2082808) of the following chemical composition (wt.%):

magnesium 5.5 ÷ 6.5 manganese 0.5 ÷ 0.8 beryllium 0.0001 ÷ 0.005 zirconium 0.05 ÷ 0.25 scandium 0.36 ÷ 0.55 chromium 0.1 ÷ 0.25 titanium 0.01 ÷ 0.05 aluminum rest

However, the set of mechanical properties characterized by the strength and ductility of welded joints obtained using the existing alloy as a filler material, in particular for welding a deformable thermally unstressed aluminum alloy economically alloyed with scandium, for example, alloy grade 1575-1 (patent No. 2268319), is insufficient.

The closest analogue adopted for the prototype is a thermally deformable wrought scandium-containing alloy based on aluminum (RF patent No. 2082809) of the following chemical composition (wt.%):

Magnesium 5.8 ÷ 6.8 Zirconium 0.02 ÷ 0.15 Beryllium 0.0001 ÷ 0.01 Scandium 0.20 ÷ 0.50 Cerium 0.001 ÷ 0.01 Boron 0.001 ÷ 0.01 at least one metal from a group containing chromium, titanium, vanadium 0.02 ÷ 0.20 aluminum rest

However, the deposited metal using filler material of the above composition due to the absence of such an important reinforcing element as manganese in the welded joints of structures made of thermally unstable (economically alloyed with scandium) scandium-containing aluminum alloy does not allow to realize high values of strength and ductility of the base metal in the metal welded joint. It should be noted the high cost of the prototype welding wire due to the high level of alloying with expensive scandium.

The technical result of the invention is to increase the strength and ductility of the weld metal and welded joint from thermally unstrengthened (economically alloyed with scandium) scandium-containing aluminum alloy, which is achieved by the fact that in an aluminum-based alloy containing magnesium, zirconium, scandium, titanium, chromium, vanadium, beryllium, boron, cerium, manganese is additionally introduced, the content of scandium is lowered, the total content of manganese, scandium, titanium and zirconium is limited within 0.95–1.3. The components are taken in the following proportions, (wt.%):

magnesium 5.5 ÷ 6.5 manganese 0.50 ÷ 0.80 zirconium 0.10 ÷ 0.20 scandium 0.25 ÷ 0.35 titanium 0.02 ÷ 0.05 chromium 0.10 ÷ 0.20 boron 0.004 ÷ 0.01 beryllium 0.002 ÷ 0.005 vanadium 0.005 ÷ 0.04 cerium 0.01 ÷ 0.05 aluminum rest

and the total content of manganese, scandium, titanium and zirconium 0.95 ÷ 1.3.

The specified technical result is provided by the formation of a homogeneous and fine-grained structure of the deposited metal with a uniform distribution of dispersed intermetallic precipitates and the absence of large crystallites.

The proposed composition of the welding wire can be used for fusion welding of deformable aluminum alloys with different scandium contents.

Magnesium and manganese in the alloy are hardeners. Due to the plastic matrix, which is mainly a solid solution of magnesium and manganese in aluminum, the plastic characteristics of the weld metal and the welded joint as a whole increase. When the manganese content in the proposed alloy is less than 0.5%, the strength and ductility of welded joints are at the level of strength and ductility of welded joints obtained using the prototype alloy as a filler material. With a manganese content of more than 0.8%, the ductility of welded joints decreases.

It is known that cerium and vanadium, introduced only in small quantities, contribute to the refinement of the weld metal structure and increase the resistance to the formation of crystallization cracks. When the vanadium content is more than 0.04%, the ductility of welded joints decreases.

Scandium, being an effective modifier, in amounts of 0.25-0.50% helps to increase the strength properties of the weld metal in welded joints from a thermally unstrengthened scandium-containing aluminum alloy. However, the use of filler material from high alloyed with scandium aluminum alloy for welding structures from thermally unstable economically alloyed scandium-containing aluminum alloy is technically and economically impractical.

Experimental studies have shown that the combined content in an aluminum alloy of a multicomponent system of alloying elements represented in a certain ratio by hardeners and modifiers, in particular manganese, scandium, titanium and zirconium, with a total content of 0.95-1.3, increases the strength and ductility of the deposited metal and welded joints of thermally unstrengthened aluminum alloys of high strength, and when welding economically alloyed scandium-containing aluminum alloy It allows realize the maximum properties of the base metal.

The complex alloying of the aluminum alloy with transition elements, including manganese, allows you to maintain high strength of the weld metal with a significant decrease in the content of scandium to 0.25-0.35% and reduce the cost of the welding wire.

When the total content of manganese, scandium, titanium and zirconium is less than 0.95, it is not possible to achieve the required strength of welded joints from deformed semi-finished products of economically alloyed with scandium aluminum alloy at a level of not less than 0.9 of the temporary resistance of the base metal due to the insufficient strength of the deposited metal, while the destruction of the butt samples occurs along the seam.

When the total content of manganese, scandium, titanium and zirconium is more than 1.3, the ductility of welded joints from sheets of economically alloyed with scandium aluminum alloy during static bending tests shows significantly lower results than joints made using the prototype alloy, despite the high strength properties of the welded connections in general.

Example

Using technical aluminum A85, magnesium MG90, double aluminum alloys with all alloying elements that make up the alloy, a melt was prepared in an electric furnace and semi-continuous casting was used to cast ingots from the proposed alloy, as well as from the known prototype alloy (table 1) of size 6 × 240 × 700 mm.

After homogenization at 375 ° C for 24 hours, cylindrical billets with a diameter of 41 mm and a length of 71 mm were cut from the ingots in the longitudinal direction. Cylindrical billets after heating in an electric furnace at a temperature of 400-420 ° C for 1 hour were placed in a heated mold and pressed on a vertical hydraulic press with a force of 250 tons onto rods with a diameter of 10 mm, then the rods after annealing at a temperature of 420 ° C for 1 cold hours were forged on a rotary forging machine for 12 passes at a diameter of 3 mm.

The obtained rods after chemical cleaning were used as an additive in multilayer surfacing, as well as in welding butt joints from sheets of a deformable thermally unstrengthened aluminum-magnesium alloy with scandium containing 0.12-0.20%, 6 mm thick.

Manual argon-arc multilayer surfacing was performed on the end face of an aluminum plate with a thickness of 50 mm and a size of 200 × 250 mm, the rollers were fused in successive layers. In total, four surfacing was made. Deposition height 20 mm, width 40 mm, length 200 mm. The strength (σ _B ) and yield strength (σ _0.2 ) limits were taken as a criterion of the strength characteristics of the deposited metal, which were determined by static tensile testing of cylindrical specimens with a diameter of the working part of 5 mm. The templates for the manufacture of samples were cut from surfacing mechanically.

To determine the strength of welded joints, manual argon-arc welding was performed with a non-consumable electrode of butt joints of sheets. Preparation of sheets for welding was carried out mechanically - V-shaped cutting of edges with a total angle of opening of edges of 70 °. Welding was carried out in 3 passes with a sample of the root of the weld, the strength of the welding current 200-250A. Standard flat specimens for static tensile testing were mechanically cut from the welded plates, the tensile strength of the welded specimen (σ _in ^sv ) was determined, and the reinforcement of the weld was not removed.

The bending angle (α °) of a flat specimen was taken as a characteristic of the ductility of a welded joint during static tests on a mandrel with a diameter equal to two specimen thicknesses. The tests were carried out before the first crack. Static bending test specimens were made mechanically from welded plates, the weld reinforcement was removed mechanically to the level of the base metal.

As can be seen from table 2, the mechanical properties of the deposited metal of the proposed alloy is higher than that of the known alloy (tensile strength higher by 20-32 MPa, yield strength by 15-19 MPa). The use of the proposed alloy as a filler material can increase the strength of the welded joint of alloy 1575-1 by 27-51 MPa. The ductility of the welded joint also increases, the bending angle increased by 17-38 °.

Claims (1)

The composition of the aluminum-based welding wire containing magnesium, scandium, zirconium, titanium, chromium, vanadium, cerium, boron, beryllium, characterized in that it additionally contains manganese, in the following ratio, wt.%:
Magnesium 5.5-6.5 Manganese 0.50-0.80 Scandium 0.25-0.35 Zirconium 0.10-0.20 Titanium 0.02-0.05 Chromium 0.10-0.20 Vanadium 0.005-0.04 Cerium 0.01-0.05 Boron 0.004-0.01 Beryllium 0.002-0.005 Aluminum Rest
while the total content of manganese, scandium, titanium and zirconium is in the range of 0.95-1.3.