SU1313616A1 - Method for machining weld joints - Google Patents

Abstract

The invention relates to methods for treating welded joints from aluminum alloys and may find application in various fields of engineering. The aim of the invention is to increase the quality and operability of welded joints with a texture: deformation oriented at an angle O - 60 ° & to the joint plane. The method consists in penetrating the heat-affected zone, having a maximum penetration depth on the fusion line of the weld. The penetration is carried out at a certain depth and width. As a result, a change in the structure is achieved: the deformation of the transition zone, the transition surface of the weld metal — the base metal becomes more complex and bent, which makes it difficult for the crack to run through it. 1. zp f-ly, 1 ill., 2 tab. with (/)

Description

The invention relates to welding, in particular to a method for treating welded joints, and can be used to improve the performance of welded joints and structures of aluminum alloys and other metallic materials having an unfavorable deformation texture in the weld edges oriented at an angle O - 60 to the plane. joint.

The aim of the invention is to improve the quality and operability of welded joints of aluminum alloys having a deformation texture in the edges being welded, oriented at an angle O - 60 to the joint plane.

The drawing shows the processing scheme.

When welding aluminum semi-finished products with a deformation texture, oriented at an angle O - 60 ° to the plane, the bones of the joint, grain and subgrain can be located parallel to or close to the fusion line. Since welding of aluminum alloys always produces intermetallic compounds and secondary phases, and their falling out is easy, but at the grain boundaries, the boundaries located in the immediate vicinity of the weld are the most weakened, the internal stresses are maximal near them, and as a result , on them passes, brittle premature destruction. The penetration on the side of the reinforcement and the root of the seam results in a change in the structure of the deformations of the transition zone, melting down the coherent fusion line along which the chain of intermetallic compounds and secondary phases fall out. The shape of the weld varies, and the transition surface of the weld metal — the base metal becomes more complex and curved, making it difficult for the crack to run along it. All of this together leads to an increase in the strength of the welded joint due to the difficulty of the propagation of a crack, a decrease in internal stresses around the fusion line, an increase in the proportion of viscous fracture, and the specific work of viscous fracture. At the location of the penetrations, when their maximum depth falls on the fusion line, the effect of increasing the strength is maximum, since the non-fused fusion zone has a minimum value.

3616. 2

The optimum depth and melting pattern were established experimentally from the condition of ensuring high strength of the welded joint and are calculated by the formulas

h (0.2-0.4) s; b (0.5-2)

(one)

(2)

five

0

0

five

0

five

0

five

where o is the thickness of the parts to be welded, mm;

h is the penetration depth, mm; b - penetration width, mm.

With a penetration depth of less than 0.2cG, the positive effect of penetration due to the improvement of the weld joint to the base metal is practically unaffected, and with penetration of more than 0.4-5, a large amount of heat is transferred to the metal, which leads to a weakening of the welded joint. The width of penetration (0.5-2) "Y is determined on the basis of the technological process and ensuring maximum strength of the joint; thus, with a width greater than 2 S, no additional strength increase is observed. I

When the maximum penetration depth falls on the fusion line, the initiation of trash injection and their propagation during stretching is most difficult, since the non-fused fusion zone has a minimum value and is clamped by passes from both sides.

The penetration by an electron or laser beam is carried out with scanning at a frequency of 0-200 Hz, which is determined experimentally from the condition of high-quality penetration depending on the rate of penetration of the scanning amplitude and the composition of the material.

The weld edges 1 are prepared for welding and assembled end-to-end with or without a gap, fusion welding is performed, after which the welding torch 2 is displaced to the weld border and the fusion zone with the melting parameters is melted using the formulas (1) and (2) at a lower current. . Moreover, the penetration can be carried out without first cleaning the surface.

Example. For welding, aluminum alloy plates were used.

3,131

welded edges of which had a deformation texture, oriented relative to the joint plane at an angle of 10. After preparing the material for welding and assembling the joint, automatic argon-arc welding with an alternating current tungsten electrode was performed, and then penetration of the zone

In tab. 2 shows the mechanical properties of welded joints at the test temperature -.

table 2

In this example, it can be seen that the use of the proposed welding method with penetration in the fusion zone increases the strength by 30-40% and the viscosity of the welded joints by 80-100%

fusing without filler wire from the side of reinforcement and propellant (root weld) by means of helium-arc welding with direct polarity tungsten electrode on direct current and electron beam with scanning.

In tab. 1 shows the parameters of the modes of welding and penetration.

Table 1

0

five

.one

Research institutes, and therefore their performance.

Claims (2)

1. A method for treating welded joints, including penetration by an arc of the near-weld zone on the reinforcement side and root weld, characterized in that, in order to improve the quality and operability of welded joints from aluminum alloys with a deformation texture oriented at an angle of 0-60 to the butt joint plane, penetration performed at depth h  (0.2-0.4) 5 and width b (0.5-0.2) 5, where (5 is the thickness of the product, with the maximum penetration depth located on the fusion line of the weld. 2. A method according to claim 1, characterized in that the penetration is carried out by a highly concentrated heat source.