Contact to authors: fond-nauka@mksat.net

Manufacturing of large ship details and units as integral toilful and complex process. Complexity of ship designs, such as anchors, arms and rudders obviously causes reception of the certain quantity of defective cast preparations [1]. To avoid occurrence of spoilage at molding, dismember on some fineer parts. However, in this case, there is a necessity of the further connection separately parts in a single whole a product. Prior to the beginning of 50th years to connection of separate parts were applied very expensive and toilful connections. Manual multipass welding of parts appeared even less effective. Despite of simplification of the form of products, expenses for manufacturing of designs have not decreased. And if it was possible to reduce ñòàíî÷íûå and metalwork works the volume of welding works immeasurably grew.

Output from this impasse was creation in the USSR of a way of electroslag welding (ESW) [2]. This way of connection has opened ample opportunities for the decision of many problems connected to improvement of quality of welded designs, decrease of their labour input, reduction of a cycle of manufacturing. 

Way of ESW at once has received application on Taganrog factory, Barnaul boiler and Is new - Kramatorsk machine-building factories, and then - at many enterprises of heavy mechanical engineering [3] and shipbuilding. Use of this progressive method of connection of metals, has allowed to change manufacture of large ship designs radically. Has disappeared necessity for creation of unique shops on capacity and units for moulding, êîâêè and machining of such large details in shipbuilding, as àõòåðøòåâíè, ôîðøòåâíè, shaft of water-wheels, beds powerful mechanical engineering, etc. 

On Nikolaev the Black Sea ship-building factory, with assistance of Institute of electric welding by E.O.Patona, electroslag welding is introduced in 1956. For example, for electroslag welding an external covering of a board of a vessel on a building berth, at thickness of sheets 14 - 30 mm., the device such as Ç-433 or the walking automatic device such as Ç-505, and further and device A-835 was used. This way had been welded coverings of the case of tankers, dry-cargo ships, whaling base “Soviet Ukraine” and other courts.

From the point of view of reception of the maximal accuracy of the sizes of welded products it is the most favourable to deal with high speeds of welding. In this case, as have shown experiences, angular both forward moving details and probability of a mistake considerably decreases at indemnification of these kinds of deformations [4]. The sizes determining process of welding [5] refer to as elements of a mode. Mode ÝØÑ is set by the following basic elements:

• a pressure{voltage} of welding- Uñ;

• speed of submission of an electrode wire-Vý;

• speed of welding--------------------------------Vñ;

• quantity{amount} of electrodes-----------------------n;

• width of a welding backlash--------------------bç;

• Width of a plate---------------------------------_bn;

• Width of a mouthpiece-------------------------------_bm;

• depth of a slag bath---------------------_hø;

• diameter of a welding wire-------------_dý;

• Thickness of a plate--------------------------------_δï;

• Thickness of a fusing mouthpiece-----------_δì.

Depth of a slag bath and diameter of an electrode or thickness of a fusing mouthpiece can be neglected, as these sizes do not depend on other elements of a mode of electroslag welding. Basic elements of ESW are the voltage of welding, speed of submission of electrodes and quantity of electrodes. Speed of submission of a welding wire_-Vý and thickness of a fusing mouthpiece - _δì define force of a welding current which together with a voltage of welding defines capacity of a source of heat. For optimum it is possible to accept such mode of welding in which all elements are picked up so, that with high quality achievement of welding quality of welded seams and accuracy of the set sizes of welded details is provided.

 The further increase in speed of welding can result in occurrence in seams cracks [6]. As have shown the experiences which have been lead by experts [7], speed of submission depends on many factors, including from conditions of fastening of details.

 We shall take advantage of Table 1. In the table skilled given influences of speed of submission of a wire and sizes ïðîòèâîäåéñòâóþùåãî the moment of M on occurrence cracks are resulted. Welding by a fusing mouthpiece of Steel by 30 thicknesses of 200 mm. The analysis of the data shows that with reduction of speed of submission of a wire, a crack in a seam appears that later, than it is less moment. And it means that with other things being equal, occurrence of cracks depends and on length of a welded seam as the seam is resistance for the angular movings, welded parts. 

Table ¹1 Skilled given influences of speed of submission of a wire and sizes of the moment on occurrence cracks 

The note: _M(0) – specific moment. 

Welding of business products with length of a joint up to 4 meters has shown, that at this speed of submission of a crack in a seam are not formed (speed of welding did not exceed 0,5 km/h). Generalizing these skilled data, for precomputations of metal by thickness 150 - 500 mm a fusing mouthpiece, are possible to recommend critical speed of submission within the limits of 120 - 140 km/h.

The size of deformations depends, with other things being equal, not only on force of a current, but also from speed of welding. At electroslag welding these sizes are connected by the following dependence:

V_c =, (1)

Where: _Fí - the area of a welding backlash, sm2;

Fì - the area of a fusing mouthpiece, sm2;

Fý - total section electrode ïðîâîëîê, sm2.

For a wire in diameter of 3,0 mm it is equal 0,071 n. The quantity of electrodes n gets out of the following parity{ratio} and is approximated to an integer:

, (2)

Where: In - thickness of metal, mm. For definition of capacity of a source of heat we can to take advantage to the formula found by practical consideration:

I = (0,022 _Vý + 90) n + 1,2 (_Vñ +0,48 Vn) _{δï bn}, (3)

Where Vn - speed of submission of a plate. Under the formula (3) it is possible to define force of a current for welding by a wire, a fusing mouthpiece and a plate. In particular, for a fusing mouthpiece (_Vn = 0), the formula gets the following kind:

I = (0,022 _Vý + 90) n + 1,2 _{Vc δm bm.} (4) 

At definition of force of a current for the wire variant, the second composed addresses in zero, and for welding by a lamellar electrode - the first composed.

Capacity of a source of heat of a slag bath, gets out proportionally to thickness of welded edges and speed of welding:

W = _{W0 Vc},

Where W0-the specific capacity of welding equal of 0,0575 kw · ÷/sm2 (specific thermal energy _qo = 50,0 kcal / sm2). Capacity of a source of heat and determine basically a temperature field of a product. Knowing a temperature field and the sizes of details, it is possible to define in the settlement way deformations of welded parts.

Deviations of the sizes of a product from set will consist of the errors admitted at assembly and errors at welding. If errors from welding not always manage to be removed, errors of assembly should be shown up to a minimum [5].

First of all, it concerns a choice of base of gauging of deformations, i.e. distance between two points located on a lateral surface of welded details on both sides from a joint. Experiences have shown [8], which the size deformation’s depends on distance between points from base of gauging. Therefore, at the indication of size of movings of welded details it is necessary to specify also and size of base of gauging. Further we shall consider, that if at the indication of size of moving the base is not underlined, the given moving has been received on the basis of 300 mm. Errors at assembly arise more often not at installation of a detail on support which arrangement defines size set of moment, and at creation of disorder of details. That is, at formation a backlash with the set corner, for indemnification of turn of details at welding [6].

For formation of a required assembly backlash [5], details usually move apart on size _bç.í (with parallel edges of a welded joint), and then make disorder of details on a corner γ that at the top of a joint the backlash made size _bç.â. However turn of details (as a rule, welded details have the various sizes and weight) changes position of edges in the bottom of a joint, i.e. size _bç.í.. It demands corrective action that complicates assembly. At limited preparatory time under production conditions, even with application of special welding stands, such system of assembly usually gives an error or demands excessive unproductive expenses of time for corrective action. That assembly of details to make more productive, without damage to accuracy of the received sizes of a welded product, it is necessary to adhere to the following rules:

1. At disorder of details with the various geometrical sizes it is necessary, that edges of a bottom of a joint laid at one height. For an arrangement of edges at one height the condition should be sustained:

γ ₁à₁ = γ₂ à_2; γ ₁+ γ₂= γ; γ ₁= à₂ (à₁ + à₂); γ₂ = γ à₁ (à₁ + à₂). (5)

In case of welding a massive detail with a small part (see fig. 2) a support 1 and 2 it is necessary to have below bottom plane of a massive detail on size: _∆h1 = _γà1 And _∆h2 = _γà2

Or is higher (á) started a joint.

2. At the task of disorder it is necessary to bring in size of an assembly backlash some indemnification which is taking into account an arrangement of support (fig. 3). If support are flush with the bottom edges of welded details or is lower than them at disorder of details of an edge will miss below, increasing size _bç.í.. Vertical ∆h and horizontal ∆L making movings of a considered point at turn of details can be found from formulas (for both welded parts):

∆h_{1 =} cos α₁ γ₁ cos α₁ = α₁ γ₁

a₂

∆h₂₌ cos α₂ γ₂ cos α₂ = α₂ γ₂

a₁ 

∆L₌ cos α₁ γ₁ sin α₁ = α₁ γ₁ tq a₁ ( 6 )

a₂ 

∆L₌ cos α₂ γ₂ sin α₂= α₂ γ₂ tq a₂ 

For observance of conditions on _{∆h1 = ∆h2} corners _γ1 and _γ2 are

Under the formula (2). Thus, the size of an assembly backlash _bç.ô. In the bottom of a joint makes:

Where ∆L = ∆L + ∆L Values ∆L and ∆L take with marks plus at increase in a backlash, and a minus at reduction of a backlash.

At formation of an external surface of a seam by copper water-cooled linings to their fastening usually apply Ã-figurative ñêîáû. These ñêîáû strongly enough press a lining to edges of a welded product, not interfering with rapproachement of details at welding. At welding long seams (two meters and more) when lining ïðèæàòû wedges on all height of a joint the size of the effort necessary on overcoming of forces of friction between a lining and a welded surface can reach{achieve} significant size. These efforts, concerning the beginning of a seam, create ïðîòèâîäåéñòâóþùèé the moment. Size of this moment which deforms size of expected deformations to take into account very difficultly.

To avoid influence ïðîòèâîäåéñòâóþùåãî the moment from friction, wedges it is recommended to hammer in the beginning of welding only in the bottom of a joint at height of 300-400 mm. Other wedges hammer on a measure of tea leaves of a welded seam.

At welding it is necessary to create identical conditions of a seam forming devices. If cooling not identical and óñàäêà welded connection with both sides of a joint will be different. There, where cooling will be smaller, there óñàäêà welded connection will be the greater. The difference óñàäêè can It quite enough that welded parts have turned in a horizontal plane, having bended the general axis of a product.

The size of a corner of turn in a horizontal plane is usually insignificant and on the average makes 0,001 - 0,002 radiuses. However at welding such long details as àõòåðøòåâåíü, turn of welded parts even on such corner, can cause a significant deviation{rejection} of the ends of a product from the general{common} axis.

For cartridges from steel thickness 25 - 70 mm, have been adapted the submitting mechanism of semiautomatic device PS-5 supplied with a special mouthpiece. A feed was carried out by a direct current. Assembly was made on technological employees also for fastening forming linings. Welding was carried out by an electrode wire under flux. In the beginning of process the arch was raised on a metal shaving. After the beginning swimming trunks of a metal shaving and excitation of an arch, the flux was fallen asleep.

Assembly backlashes and modes of welding of cartridges are resulted in Table 2 and Table 3. After the radiographic control, over removal of voltage of the cartridge were exposed to holiday. Metal has structure of cast steel. The zone structure with a point of a grain 4 - 6. Then there is a structure with a point of a grain 5 - 6. Hardness on all sites is identical.

 The note. Backlashes can change depending on diameter and thickness welded product. 

Welded large courts. 

For welding ship-building details by thickness up to 250 mm, device A-372r with transformer TSHS-600-3 and a wire in diameter d = 3 mm was used. For welding metal by thickness up to 500 mm the welding automatic device also was above used.

Now by electroslag welding are made ship øòåâíè for tankers, dry-cargo courts, the big freezing trawlers and for military shipbuilding. Productivity of electroslag welding rather high. For example, a product section 400 õ 400 mm and height 500 mm. It was welded for 50 minutes, and section 450 õ 700 mm. - for 1, 5 hours. After performance of process all joints should be without fail subjected to local high-temperature thermal processing (to normalization and holiday) in electric furnaces. 

After high-temperature thermal processing mechanical properties of welded connection meet the requirements, showed to the basic metal. However the limit of fluidity is reduced up to 30 kg/mm^2 at welded connection from steel and up to 25 kg from special steels.

The used adaptations providing qualitative welding represent copper figured linings cooled by water. Such adaptations allow carrying out welding of products by thickness up to 1000 mm and are higher. It is necessary to stop on technological sequence of tea leaves of joints closed contour. These apertures are muffled by the fuses scalded on a contour that creates additional concentration of voltage. During distance of external technological inflow with the help gas are sharp on one of joints close, in the central part of welded connection, after the common thermal processing øòåâíÿ the crack which has left on a surface has appeared.

Carried out together with Institute of electric welding researches, have allowed to develop technology which provides reception of welded connections the closed high quality contour and without cracks. Before welding of last joint heating in the electric furnace of an opposite site, up to increase in a backlash in a joint on 4 - 5 mm (size usual óñàäêè a joint of the given section) is made. After welding a furnace it was disconnected, and the welded joint was cooled simultaneously with the heated up site. This technological reception provided decrease of additional voltage.

Very important at manufacturing, before foundry apertures to execute on small through apertures. Absence of such apertures on resulted one in its destruction on a site between welded joints during the common thermal processing in the furnace. Assembly backlashes and modes of welding are resulted in Table 4 and Table 5. 

Table 4. Assembly backlashes

The note. Backlashes can change depending on diameter and thickness of a welded product.

The partition on the greater number of details has allowed lowering spoilage at casting preparations. Details prepare under welding only on one machine tool, also "apple" here is pierced. Details have on the ends rectangular technological inflow in length on 100 mm. replacing introduction plates. From welded connection near to the technological inflow leaving for working section, samples for mechanical tests are cut out. From the bottom side "pocket" becomes isolated a steel rod.

Before application, rudders were made from preparations. At machining preparation in a shaving left up to 40 - 50 % of metal. Now technology combined rudders from steel at which the cast part is cast in the pure size is applied, and rod is made with the minimal allowances. At connected end faces of a detail have technological inflow from which samples for mechanical undertake Tests. At manufacturing áàëëåðîâ in welded variant in a shaving leaves no more than 10 - 15 % of metal.

Table 5. Modes of electroslag welding

The note. Depth of the fused bath within the limits of 50-:-60 mm.

Welded by an electroslag way rudders are rather responsible designs working in very complex conditions at sign-variable loadings, high and low temperatures. While in service on courts of the various tonnage and the purpose, floating in tropical and Arctic conditions, and also in conditions of the Antarctic breadthes, these products have shown reliability and serviceability.

HIGH-TEMPERATURE THERMAL PROCESSING 

After process of electroslag welding all joints, together with ïðèõâà÷åííûìè to them inflow, are exposed to local thermal processing (to normalization and holiday) in electric furnaces. Electric furnaces will consist of two mobile and independent sliding parts. Capacity of furnaces from 35 up to 70 kw. The temperature necessary for heat treatment (in position “ on a joint ”) is established by a furnace for four - five hours. Normalization is carried out at temperature t = 940 … 960Ñ, and holiday at tî = 640 … 660Ñ [8]. In case of the big dimensions of a design and impossibility of carrying out of local thermal processing what or a welded joint - all design is exposed to thermal processing. Local thermal processing is made in portable furnaces. For registration and automatic control of process of thermal processing, portable furnaces are equipped with recording devices. 

Table ¹6 Backlashes at welding wire an electrode

The note: It is supposed the lateral faces lying in one plane, in limits ± 1, 5 mm. On all length.

Mechanical properties should correspond to the norms resulted in tab. ¹ 7.

Samples for tests, are cut out from the inflow past thermal processing together with joints from which they have been cut off. At failure of automatic control of temperature, it is necessary to make the subsequent tests of mechanical properties of welded connection. Samples for test are cut out from the inflow last thermal processing together with joints from which they have been cut out. 

The given modes of local thermal processing of a welded joint áàëëåðîâ are valid only for a combination of steels; and an arm. Local thermal processing will consist of normalization and holiday.

1. NORMALIZATION

The temperature of heating of the furnace at normalization of joints of welded designs is equal 940 - 970Ñ. Time of endurance in the furnace at temperature 940 - 970Ñ is equal to three - five hours from the moment of achievement by both thermocouples of the set temperature. Cooling on air before full dimness at moved apart furnaces. After that additional cooling by the compressed air is supposed.

2. HOLIDAY

At holiday of a furnace it is heated up to temperature 640 - 670Ñ. Time of endurance at temperature 640 - 670îÑ usually makes six - seven hours. Cooling on air furnaces move apart so that the distance of cooled joint was not less than 1,5 - 2,0 meters. Time of endurance of designs at normalization and holiday depending on section can be presented in a tabulated kind (Tab. ¹ 8).

Process of thermal processing is fixed in magazine. As a rule, such data as enter the name: the name and number of the drawing of a design; numbers of swimming trunks of the welded preparations. Numbers of joints and the set modes of heat treatment. Date and time of carrying out of heat treatment, actual modes of processing with fixing through everyone 10 - 15 minutes, or according to technological process.

At all obvious advantages of electroslag welding, this way of connection of metals has also essential lack. This obligatory application of high-temperature thermal processing. Despite of high efficiency, from the point of view of the decision of practical problems connected with improvement of structure and mechanical properties of metal of a seam zones, high-temperature heat treatment has a lot of essential lacks [7]. To them concern: high cost of heating furnaces, significant lengthening of a cycle of manufacturing of a welded design, danger of gross infringement of geometry of a processable product, etc. Therefore interest to this problem, and also to a problem of creation of such advanced technology which will allow simplifying is clear or even completely to exclude all operations connected with high-temperature thermal processing.

1. Feygin O.O. Action of high-energy electroimpulses on metal melts // Sciteclibrary (2003). - http://www.sciteclibrary.ru/eng/catalog/pages/5294.html

2. Korneev D.I., Feygin O.O. Paradoxical physics of super-power impulsing discharges // Ibid. - http://www.sciteclibrary.ru/eng/catalog/pages/5347.html

3. Korneev D.I., Feygin O.O. Phenomenological thermodynamics of super-energy electroimpulses in metal melt // Ibid. - http: // www.sciteclibrary.ru/eng/catalog/pages/5422.html

4. Korneev D.I., Feygin O.O. Thermodynamics of fluid metals at ultrahigs energies of electrocurrent action // Ibid. - http: // www.sciteclibrary.ru/eng/catalog/pages/5454.html

5. Petrenko S.S., Feygin O.O. Nonequilibrium crystallization of metal melts // Ibid. - http: // www.sciteclibrary.ru/eng/catalog/pages/5687.html

6. Korneev D.I., Feygin O.O. Quasicrystallization of metals at ultrahigh energy of action // Ibid. - http: // www.sciteclibrary.ru/eng/catalog/pages/6078.html

7. Korneev D.I., Feygin O.O. Electrophysical methods of control by the crystallization of welded metal // Ibid. - http: // www.sciteclibrary.ru/eng/catalog/pages/6302.html

8. Korneev D.I., Feygin O.O. Theoretical explorations of processes high-energy electrophysical treatments of metal’s melts // Ibid. - http://www.sciteclibrary.ru/eng/catalog/pages/6436.html

9. Korneev D.I., Feygin O.O. Mechanisms of the operation of electroimpulses channels in the metal's melts // Ibid. - http: // www.sciteclibrary.ru/eng/catalog/pages/6586.html

10. Korneev D.I., Feygin O.O. Superhigh - energy electroimpulses in the metal's melt // Ibid. - http://www.sciteclibrary.ru/eng/catalog/pages/6649.html

11. Petrenko S.S., Feygin O.O. Macro - nonequilibrium model of the quasicyclic solidification of metal – alloys // Ibid. - http://www.sciteclibrary.ru/eng/catalog/pages/6651.html

12. Korneev D.I., Feygin O.O. Superenergy electropulsing treatment of weld joints // Ibid. - http://www.sciteclibrary.ru/eng/catalog/pages/6669.html

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