SU1754381A1 - Welding electrode - Google Patents

Abstract

Use: manual arc welding with alternating current electrode supported on the edges of the product to be welded. The invention relates to welding and relates to the composition of an electrode coating that is applied to a high-alloy rod. The electrode is intended for making welded joints of dissimilar or high alloyed steels on alternating current in hard-to-reach places, with the electrode resting on the edges of the product being welded during the welding process. At the same time, the seam is formed without arcuate transverse or circular reciprocating, as well as longitudinal or any other movement: the rod is made of high-alloyed chromium-nickel steel containing 2 to 8% of the ferritic phase and is coated with components containing the following ratio, wt.% : marble 15-21; dolomite 10-14; fluorspar 5 - 7; rutile concentrate 30-40; metal manganese 2-4; ferrosilicon 2-4; metallic chrome 4-14. plasticizer 0.2 - 1.5; iron powder - the rest. Dolomite, marble and fluorspar are taken in a ratio of 1: (1.4 - 1.7) :( 0.4 - 0.55), and the content of metallic chromium in the coating (% MF) and ferritic phase (% F) in the electrode rod in the sum should meet the following relationship: 12% MF + FЈ 16%. The mass ratio of the coating of the proposed electrode should be 47 + 2%. If the specified ratios of the components are observed, the electrode provides, while resting on the edges, high quality welds in hard-to-reach places. 2 tab. the end of the electrode, typical of conventional manual arc welding. The absence of the need for oscillatory movements of the electrode during welding allows high-quality, responsible welded joints to be made in hard-to-reach places by a low-skilled welder. In this case, the requirement for obtaining such high-quality welds is the absence of magnetic blowing. This is achieved by using alternating current to power the welding arc. Therefore, the electrode must provide 10 C VI ate N CO 00

Description

stable welding process and good weld formation when using an AC power source.

Such an electrode can be used, in addition to manual welding, also for welding by means of auto-contact welding and welding with an inclined electrode.

An electrode is known, for welding by a method of an inclined electrode with a coating containing the following components, in wt%:

Silica 14-23

Titanium dioxide 5-16

Zirconia 0.5 - 7.0

Manganese4-11

Iron powder37 - 60

This coating is applied to a carbon steel rod and is intended for welding carbon steel products. Making a rod of high-alloyed chromium-nickel steel of austenitic-ferritic class to enable welding of dissimilar and high-alloyed steels does not allow with a known coating to obtain a weld without cracks when welding high-alloyed and dissimilar steels, for example VSTZ steel with 1X13 steel or VSTZ with 1X18H9 steel.

A known electrode for welding and surfacing, consisting of a doped rod and a coating, which, in order to increase the strength properties of the weld metal in the absence of a tendency to hot cracks, contains 2 to 4% chromium carbide and 1 to 2% potassium lump in the following ratio, wt. %:

Marble8-10

Fluorspar3-5

Titanium dioxide45 - 50

Molybdenum powder 1-3 Xm ohm metal 22 - 28 Manganese5-7

Potash 0.5 - 2.0

Chromium carbide2-4

Potassium-sodium lump 1-2

This coating is applied to the rod of high-alloy steel and makes it possible to weld with alternating current parts of different thickness from dissimilar steels by manual arc welding. However, when using this electrode to make welded joints without any movement of the end of the electrode (the electrode is stationary and rests on the edges of the product being welded), a positive result is not achieved: the arc is unstable; suture formation unsatisfactory; pores are observed in the weld

The composition of the electrode coating for welding steels, containing marble, titanium oxide, fluorspar, deoxidizing agents, chromium, molybdenum and plasticizers, which, in order to improve the welding-technological properties of the electrode with a ferritic-martensitic-steel rod, improve the mechanical properties and the impact toughness of the weld metal at negative temperatures contains chromium oxide, nickel, iron powder, ferromolybdenum in the following ratio, wt.%: Marble6-11

Titanium oxides12-22

Fluorspar 21 - 38,5 Deoxidizers3-9

Ferromolybdenum 0.5 - 3

Chromium oxide3-6

Chrome 7-12

Nickel7-10

Plasticizers0.5 - 2

Iron Powder Rest

The above coating allows manual arc welding of ferritic-martensitic, martensitic and austenitic-martensitic stainless steels, as well as these steels with other structural classes at direct current of reverse polarity. However, when using this coating (when applied to a rod of austenitic steel of type H25H13), for welding with alternating current, an electrode supported on the edges of the product to be welded also fails to achieve a positive result: the arc burns with breaks; suture formation is unsatisfactory; pores and cracks are observed in the weld metal.

The purpose of the invention is to improve the quality of the weld when welding with alternating current resting on the edges of the product to be welded with an electrode.

The goal is achieved by the fact that the rod is made of high-alloyed chromium-nickel steel of type X23H18 with a content of ferritic phase of 2–8%, and dolomite is additionally introduced into the electrode coating in the following ratio of components, wt.%:

Marble15-21

Dolomit10-14

Fluorspar5-7

Rutile concentrate 30 - 40 Manganese metal 2-4 Ferrosilicon2-4

Metal chrome4-14

Plasticizer0,2-1,5

Iron powderEverything.

The proposed coating also selected the ratio of marble (M), dolomite (D) and fluorspar concentrate (P), which ensure stable arc burning in the case of feeding it from an alternating current welding source and good formation of the weld when it melts Divide the electrode with a rod of high-alloy steel without longitudinal oscillations of the end of the electrode, characteristic of manual arc welding.

The selected ratio of components is determined by the expression D: M: P 1.0: (1.4-1.7) :( 0.4-0.55).

The amount of metallic chromium in the coating (% Cg) and the ferritic phase (% F) in the electrode rod should total amount to the ratio of 12%: Cg + F: 16%. however, the mass ratio of the coating should be 47 + 2%.

Violation of these ratios leads to deterioration of the formation and quality of the seam or to the deterioration of the separability of the slag crust. Marble and dolomite were added to the coating to provide gas-slag protection against nitrogen in the air in order to prevent the formation of pores. The content of marble with dolomite below 25% (marble 15%, dolomite 10%) leads to the formation of pores in the weld. An increase in dolomite and marble by more than 14% and 21%, respectively, causes an excessive increase in the length of the sleeve at the end of the electrode, leading to a break in (attenuation) of the welding arc.

Fluorspar concentrate is added to the coating composition also to prevent the formation of hydrogenous porosity. When the content of this component in the coating is less than 5%, pores are formed in the weld. When the content of fluoride sputter concentrate is more than 7%, the stability of the welding arc is impaired.

Rutile concentrate was introduced into the composition of the coating for the slag protection of the deposited metal from nitrogen in the air, as well as to ensure the steady burning of the welding arc on alternating current.

If less than 30% of rutile concentrate is contained, then in the process of electrode melting, breaks in the welding arc are observed. When more than 40% of the rutile concentrate is contained in the coating, the uniformity of the slag coating of the weld is disturbed and the formation of crystallization cracks in the welds is deteriorated. amount

this component in the coating varies within the specified limits depending on the content of the ferritic phase in the electrode rod.

A decrease in the chromium metal content in the coating of less than 4% and less than 14% when the content of the ferritic phase in the electrode rods is 8% and 2%, respectively, leads to the formation of hot cracks in the welds. An increase in the chromium metal content in the coating of more than 4% and more than 14% when the content of the ferrite phase in the electrode rods of 8% and 2%, respectively, causes embrittlement of the weld metal due to the formation of α-phase and leads to cold cracks.

An additional ferrite-forming component in the coating composition is ferrosilicon. Ferrosilicon in the coating protects the silicon contained in the wire from burnout; as a result, its amount in the weld metal is maintained at a constant optical level of 0.7–1.0%. A decrease or increase in the content of ferrosilicon in the coating compared to the specified limits (2–4%) causes a change in the content of the ferritic phase in the weld metal less than 5% or more than 8%, which can lead to the formation of hot or cold cracks in the welds .

Manganese is incorporated into an electrode coating to bond sulfur to refractory oxides in a crystallizing metal, which increases the ductility of the weld metal as a result of its binding. When the manganese content is below 2%, the required ductility of the weld metal is not ensured. With an increase in the manganese content in the coating above 4%, the separability of slag during welding deteriorates.

Plasticizers contained in the coating in the amount of 0.2 - 1.5% provide the necessary manufacturability of the coating mass in the manufacture of electrodes on high-pressure presses. Potash, carboxymethylcellulose, (CMC), mica, soda ash can be used as plasticizers. When the content of the plasticizer is less than 0.5%, pressing of the electrodes is difficult; when the content of the plasticizer is more than 3%, the content of hydrogen in the weld metal increases unacceptably.

Iron powder has a positive effect on arc stability and increases the deposition rate of the electrode.

The manufacture of electrodes was carried out by crimping on an AEE-1 high pressure press. It was manufactured 14 electrodes, the compositions of which are listed in Table 1. The ratio of the mass of the coating was 47 ± 2%.

Compositions 2-6 correspond to the limiting values, while compositions 7 and 8 correspond to the exorbitant values, since the ratio of 12% Cr + ФЈ 16% was not observed. Electrode coatings 9-14 were made to confirm the correctness of the choice of the ratio of marble, dolomite and PCF concentrate. Wire X25N13 was used as a rod. Electrodes, manual welding, made welded joints of plates from steel grades VSTZ and 1X13, while observing the welding process and assessing the quality of the coating of the electrodes.

During the welding process, the electrode was supported on the edges of the product being welded, and the electrode axis was inclined to the weld axis at an angle of 8-12 °. The end of the electrode was fixed in the transverse direction. Electrodes with a diameter of 5 mm were used for welding. Welding was performed using a UDGU-301 alternating current power source equipped with a stabilizer pathogen, in the mode of: current 200 - 210 A; voltage 24-26V.

The test results given in Table 2 show that the proposed electrode, in comparison with the known ones, allows welding with alternating current by supporting the electrode with the rod of high-alloyed steel on the edges of the product to be welded, while well-formed welds are obtained and good separation is ensured. slag crust from the surface of the seams. This allows welding in hard-to-reach places.

Claims (1)

Invention Formula A welding electrode consisting of a high-alloyed rod and a coating containing marble, fluorspar, rutile concentrate, metallic chromium, metallic manganese, ferrosilicon, iron powder and plasticizer, characterized in that, in order to improve the quality of the weld with alternating current welding with an electrode , resting on the edges of the product being welded, the high-alloyed rod is made of steel of type H25H13 with a ferritic phase content of 2 to 8%, and the electrode coating additionally contains dolomite at the following the ratio of components, wt.%: Marble15-21 Dolomit10-14 Fluorspar5-7 Rutile spar5-7 Rutile concentrate 30 - 40 Manganese metal 2-4 Ferrosilicon2-4 Metal chrome4-14 Iron powder5-21 Plasticizer0,2-1,5 At the same time dolomite (DO, marble (M) and fluorspar (P) are taken in the ratio D: M: P 1: (1.4 - 1.7) :( 0.4 - 0.55), and the content ( % Cr) of metallic chromium in the coating and the ferritic phase (% F) in the electrode rod together corresponds to the following ratio: 12% Ј Cr + FЈ 16%, with the weight ratio of the electrode coating being 47 + 2%.