SU1489935A1 - Method of protecting the underside of weld in multipass welding of hard-melting alloys and metals - Google Patents

Abstract

The invention relates to welding and can be used in chemical engineering for arc multi-pass welding of refractory metals with forced cooling of the joint zone when creating chemical devices from zirconium and other refractory metals. The purpose of the invention is to improve the quality of welded joints by preventing preheating of the edges of the blanks with heated aluminum. The first pass is welding the blunting. A layer of aluminum is sprayed onto the edges of the jointed blanks from the root of the weld, in which grooves are formed with a width equal to the thickness of the deposited aluminum layer and a step equal to (1-2) δ, where δ is the thickness of the joined blanks. The grooves are oriented across the edges to be welded. After that, the filling is done with filler material. The transverse grooves in the aluminum coating allow halving the width of the recrystallized grain in the heat-affected zone. 1 ill., 1 tab.

Description

The invention relates to welding and can be used for arc multi-pass welding of stainless steels and refractory metals and alloys with forced cooling of the connection zone.

The purpose of the invention is to improve the quality of welded joints by preventing the heated edges of the blanks with heated aluminum in front of the weld pool.

The drawing shows the welding scheme for the proposed method.

The method is implemented as follows.

Welding of workpieces 1 is carried out in argon with an edge-free, non-melting tungsten electrode. First, weld the blunt with a welding seam 2. Then, the surface of the blanks and the weld seam on the root side is treated with a scraper or a shotgun. After cleaning, a layer of aluminum 3 with a thickness of 0.6-rl mm is drilled onto the metal surface. The aluminum coating of the specified thickness has sufficient strong adhesion to the surface of the welded blanks. Then across the edges of the workpieces in increments of

four

00

x

00:

sd

148

(... 2) 5, where 5 is the thickness of the joint blanks, in a layer of aluminum is formed in a known manner, for example milled, transverse grooves 4 with a width equal to the thickness of the deposited layer of aluminum. After that, the cutting of edges is filled with an additive material, forming a seam 5. Welding is carried out in modes in which the aluminum is heated to the melting temperature, but not more than 1000 ° C to prevent the formation of intermetallic B. During the welding process, no additional protection of the root weld with argon is produced. Molten aluminum reliably protects the metal from interaction with active gases. The transverse grooves do not reduce the quality of welding protection. In the process of welding, aluminum expands and the grooves in the coating are molded, which ensures reliable protection of the root of the seam against interaction with active gases.

It follows from the dansh-1x table that the transverse grooves in the aluminum coating can reduce the width of the recrystallized grains in the HAZ zone by almost half, significantly increase the bend angle and impact strength of the welded joints. The optimal step of breaks (1 ... 2) 5. A reduction in the transverse groove pitch to O 58 leads to a deterioration in the quality of protection of the root of the seam, a decrease in ductility and toughness of the welded joints and increases the width of the HAZ due

joints, since the aluminum preheating of the edges is melted well before the grooves of the weld pool intersect. This leads to the melting of grooves with aluminum during the welding process. .

After welding, the aluminum layer, when necessary, is removed in a known manner, for example, it is etched or removed during machining.

Example. Argon-arc arc welding of plates with a thickness of § 7 mm from Zr alloy — 2.5% Nb with V-shaped edge grooving was performed. The first pass produced welding dullness without filing filler wire on

35

billet aluminum. The width of transverse gaps, equal to the thickness of the aluminum coating, is chosen from the condition of providing high-quality protection of the seam against interaction with active gases. Increasing the width of the gaps leads to thinning of the film of melted aluminum and deterioration of protection quality, while there is no melting Aluminum grooves. Thus, a positive effect is achieved by forming transverse grooves in the aluminum layer.

The economic effect is expected to come from replacing the Zr-l% Nb alloy with a higher strength Zr-2.5% N alloy to create welded chemical devices. This will allow to reduce the consumption of zirconium by 25%, and reduce the cost of chemical devices. It can be used in mechanical engineering to create welded chemical apparatuses from horses, and other refractory metals, stainless steels, as well as in other sectors of the national economy.

fjj mode 0.84 cm / s; 1, 200 A; and l 11 V. After that, the seam and edges of the blanks were processed with a scraper and a layer of aluminum 0.8 mm thick coated with a gas metallizer MgaZ-57 using aluminum wire AK 2 mm in diameter. Then, in the aluminum coating with a step of 0.5 ... 3, the grooves were made with a width of 0.8 mm. After that, the cutting was performed - filler wire made of Zr-1% Nb alloy with a diameter of 2 mm in the mode

V

se

0.28 cm / s; leg, 320 A;

%

 14 V; Van. 1.5 cm / s. The quality of welded joints was determined by mechanical testing of welded joints for a static and impact bend, the microtiderness of the metal in the root of the weld on the 8-µm lip at the grooves and the width of the recrystallized grain section in the HAZ (see table).

55

In the process of welding, protection of the root seam with argon was not made.

0 edge preheating

five

about

five

0

five

five

billet aluminum. The width of the transverse gaps, equal to the thickness of the aluminum coating, is chosen because of the quality of the seam root protection against interaction with the active gases. Increasing the width of the gaps leads to thinning of the molten aluminum film and deterioration of the quality of protection, while there is no melting of aluminum grooves. Thus, a positive effect is achieved due to the formation of transverse grooves in the aluminum layer.

The economic effect is expected to come from replacing the Zr-l% Nb alloy with a higher strength Zr-2.5% Nb alloy to create a welded chemical apparatus. This will allow to reduce the consumption of zirconium by 25%, and reduce the cost price of chemical devices. The invention can be used in chemical engineering to create welded chemical apparatuses from zirconium and other refractory metals, stainless steels, as well as in other branches of the national economy.

Claims (1)

Invention Formula The method of protecting the back side of the seam when arc multi-pass welding of refractory metals and edge grooved alloys, in which dulling is performed by the first pass, is deposited a layer of aluminum on the edges of the jointed workpieces from the root side, and then filling the groove with filler material, tl and h and y y and y .; topics 514899356 that, in order to improve the quality of welding, from 8 to 2§, where S is the thickness of the compound., compounds in the aluminum layer are grooved with a width equal to the thickness of the deposited aluminum layer and billets, mm, with the grooves located across the edges to be welded. billets, mm, with the grooves located across the edges to be welded.