SU1611653A1 - Method of producing specimen having welding defects - Google Patents

Abstract

The invention relates to welding, in particular to methods for obtaining a sample with welding defects, and will find application in the study of the properties of welded structures. The purpose of the invention is to provide the possibility of obtaining defects such as concavity of the root of the seam in thin-walled samples from light alloys with a given location and size of defects. The sample is welded on a lining with a layer of organic gas-forming substance deposited on its surface. Welding is carried out on a current that is 5–20% less than the optimum, and with an arc length that is 50–100% more optimal for the given welding conditions. The method makes it possible to save 2-4 times in research work materials, electricity and labor. 2 hp f-ly, 6 tab.

Description

The invention relates to welding, in particular, to the preparation of samples with defects, and can be used to study the effect of defects such as root concavity on the properties of welded joints, mainly light alloys.

The method provides obtaining defects in samples with straight, circular and circular seams.

The aim of the invention is to provide the possibility of obtaining defects such as the concavity of the root of the seam in thin-walled samples from light alloys with a given location and size.

Collect a sample of two plates that are placed on the lining. An organic gas generating agent is applied to the surface of the lining. Welding is performed on a current of less than 5-20% of the optimum value.

The essence of the method is the use of local overpressure of the gas phase on the liquid weld pool. In the initial period of formation of the weld pool, this overpressure raises the melt above the pad, followed by balancing by the forces of surface tension, arc pressure and the gravitational forces of the melt, which crystallizes to form the concavity of the root of the seam. In order to create the necessary amount and composition of the gas phase, high-temperature and high-molecular organic matter is selected, which is applied to the flat lining. Then, the exact assembly of the joint without a gap in the center of the applied layer and the pressing of the plates being welded are performed. Welding is carried out with a filler wire with a welding current 5-20% less and the arc length 50-100% higher than the optimum welding. At the same time, the reinforcement of the upper roller is formed to a height of 20-80% of the edges being welded.

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The width of the applied layer of a substance is determined based on the width of the required concavity and the formation of a quantity of gas phase sufficient to create an overpressure that raises the liquid weld pool and is equalized by hydrostatic pressure and surface tension of the melt metal. An excessive increase in the layer width leads to the formation of such a quantity of the gas phase, which breaks the melt continuity and leads to the formation of progresses and chains of small ducts.

A decrease in the welding current by 5–20% and an increase in the arc length by 50–100% were chosen experimentally to reduce the specific pressure of the welding arc on the molten bath.

Since the gas phase released during heating raises the weld pool above the lining, it is necessary to slightly lower it to prevent burn-through. A reduction of less than 5% does not allow to obtain a qualitatively stable result, and more than 20% does not allow a uniform weld pool, without inconsistencies and oxidized films. Increasing the arc length by 50-100% allows reducing the specific pressure of the welding arc on the melt so that the welding process is stable, without interruptions and without strong mixing (lower limit) of the weld pool.

Strengthening the upper bead of the weld by 20-80% of the thickness of the edges above the surface of the weldable thicknesses was established based on the creation of such a quantity of molten weld metal that the melt pressure and surface tension forces are balanced by the pressure of the excess gas phase. With increasing gain, more than 80% of the melt sags in some places, violating the uniformity of the defect, and less than 20% is not enough to form a solid welding bead.

Compounds from the group of high-temperature and high molecular weight alcohols are used as organic matter applied to the lining. These organic compounds do not evaporate at room and elevated (up to 80 ° C) temperatures, but decompose when strongly heated (above 150 ° C) into simple derivatives, most of which are volatile, forming a gas phase, lifting the weld pool metal above the lining. ,

The implementation of welding on the lining with a proplavoobrazuyu groove depth of 5-50% of the thickness of the welded edges, along which is applied organic in

In effect, a discontinuous weir type defect can be obtained by partially removing the excess gas phase through the groove channel. Since excess gas

the phase has the ability to move along the groove during welding heating, the molten metal in the melt in some places reaches the bottom of the groove, isolating (blocking) a part of the gas phase, which in

these places forms the concavity of the melt. This results in a wave-shaped formation of the propellant. With a groove depth of less than 5% of the thicknesses being welded, the gas phase does not have time to get out of the weld pool and there are defects like concavity of the melt. An increase in depth of over 50% leads to the need to increase the amount of filler wire supplied, which causes the appearance of

0 incomplete welding when welding on the recommended modes.

Example, You need to get a defect. type of concavity of the root of the seam when welding AMGB alloy plates with a thickness of 3 mm. Recommended dull optimal mode

automatic argon arc welding of this material: 1cv 180-A, VCB 18 m / h,

1mm - 3 mm.

When choosing the welding mode for obtaining a defect, welding was carried out on a steel flat lining, welding speed 18 m / h, arc length 3 mm. The joint was assembled without a gap, a layer of nitroglycerin up to 15 mm wide was applied to the lining.

5 Data on the choice of ice welding are given in Table. one.

In all cases, small lathes with a diameter of up to 1.5 mm were formed in the base metal from the propellant side. 0 Data on the choice of arc length in welding mode: ice 160 A, VCB 18 m / h, are given in Table. 2

Data on the choice of the width of the applied layer of glycerin during welding by the mode: ice 5 160 A, VCB 18 m / h, 1 arc 5 mm, are given in Table. 3

The data on the choice of the height of the weld reinforcement when welding according to the mode: ice 160 A, VCB 18 m / h, 1 arc 5 mm, and a width of 50 layers of glycerin not more than the width of the penetration are given in Table. four.

Based on the test results given in table. 1-4, it can be seen that the guaranteed receipt of a stable defect 55 of the type of concavity of the root of the seam is provided with the proposed range of parameters.

Comparative data on the proposed and known methods are given in table. five.

Data on the choice of organic matter are given in table. 6

Kak can be seen from the table. 5, the proposed method for obtaining defects such as the concavity of the root of the seam ensures that this defect can be obtained along the entire length of the weld or at specified sites. The method allows significant (2–4 times) saving in research work material, electricity and labor costs.

Formula a and 3 o brethren and

Claims (3)

1. A method of obtaining a sample with welding defects, in which a sample is welded from two plates that are placed on the lining, assemble them without a gap and are welded with a filler wire, characterized in that, in order to ensure the possibility of obtaining defects such as root concavity in thin-walled samples of light alloys with a given location and size are performed marking of the lining and plates, applied to the surface of the lining facing the plates, the organic gas-generating substance when heated to a width not less than the calculated width of the root of the seam, welding is carried out on the welding current less than 5-20% 100% of the optimal values of these quantities, forming a weld reinforcement to a height of 20-80% of the thickness of the plates. 2. A pop method, 1, characterized in that a substance from the group of high-temperature typflfcix and high molecular weight alcohols is taken as an organic substance. 3. Method according to paragraphs. 1 and 2, so that, in order to ensure the production of a discontinuous weft root defect, welding is carried out on the lining with a forming groove with a depth of 5-50% of the thickness of the plates with the application of a gas generating agent groove. Table 1 1cb, A The results of visual and x-ray controls The concavity is very deep, in some places burns The concavity is deep, uniform along the length of the sample. Also The concavity is shallow and uneven, in some places of non-fusion up to 5 mm in length and oxide films up to 7 mm in length  arc, mm The results of visual and x-ray controls The concavity is uneven, in some places the weld burn-through The concavity is smooth, the burn-through weld seam. The concavity is smooth along the entire length of the weld. Same The concavity is uneven, in some areas of non-fusion up to 4 mm in length table 2 Layer width b Visual inspection results More than 5 mm to the side of the fusion zone from the side of the propell 1-2 mm wider suture root No wider suture root Along the boundary of the fusion zone from the side of the propla 3 mm wide, the zone with fine wearers (up to 1.5 mm in diameter) Along the boundary of the fusion zone, fine wets in the base metal, the concavity is even Along the boundary of the fusion zone from the side of the propell in the base metal, no webs were detected; concavity is smooth, stable Height h, mm Visual inspection results Concavity uneven, burn-through The concavity is flat, no burns are observed. Also The concavity is uneven, the folds in the melt Way Welding mode my  And m / h 1du M M B width of fusion  BUT  m / h 1 arc 5 mm B width of fusion  And m / h 1 arc 5 mm B width of fusion  BUT  m / h 1 arc 3 mm B width of fusion  BUT  m / h  arc 3 mm B width of fusion Table 3 Table 4 Table 5 Inspection Results The concavity is unstable, non-fusion and pores in the weld Concavity is stable, smooth Concavity uneven, burn-through The concavity is unstable, the burn-throughs in the weld The concavity is even, stable, no burn-through, along the fusion zone in the base metal of the rod with a diameter of up to 1.2 mm Organic matter VM 6 vacuum oil Paraffin Glycerol 1611653 10 Table 6 results Contamination gain, pores and non-fusion Weld seams, pores, non-fusion up to 7 mm long, oxide films up to 5 mm long The quality of the seam is even, without contamination.