GOST 30482-97

• gost-30482-97.pdf (835.07 KiB)
  ГОСТ 30482-97

GOST 30482−97 the electroslag welding of steels. Requirements for technological process

GOST 30482−97

Group В05

INTERSTATE STANDARD

THE ELECTROSLAG WELDING OF STEELS

Requirements for technological process

Electroslag welding of steels. Requirements for technological process

ISS 25.160.10
AXTU 0072

Date of introduction 2002−01−01

Preface

1 DEVELOPED by the Institute of electric them. E. O. Paton of the National Academy of Sciences of Ukraine; Intergovernmental technical Committee for standardization MTK 72 «welding and allied processes"

SUBMITTED to the State Committee of Ukraine for standardization, Metrology and certification

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (minutes N 11 dated 23.04.97)

The adoption voted:

The name of the state	The name of the national authority for standardization
The Republic Of Azerbaijan	Azgosstandart
The Republic Of Armenia	Armastajad
The Republic Of Belarus	Gosstandart Of The Republic Of Belarus
The Kyrgyz Republic	Kyrgyzstandard
The Republic Of Moldova	Moldovastandart
Russian Federation	Gosstandart Of Russia
The Republic Of Tajikistan	Tajikistandart
Turkmenistan	Glavgosekspertiza «Turkmenstandartlary"
The Republic Of Uzbekistan	Standards
Ukraine	Gosstandart Of Ukraine

3 Resolution of the State Committee of the Russian Federation for standardization and Metrology, dated 22 January 2001, N 26 St interstate standard GOST 30482−97 introduced directly as state standard of the Russian Federation from January 1, 2002.

4 INTRODUCED FOR THE FIRST TIME

1 Scope

This standard establishes requirements for the technological process of electroslag welding (hereinafter — ESW) wire electrode or consumable mouthpiece carbon and low alloy steels with alloying elements less than 2.5%.

The standard does not apply to electroslag welding with a plate electrode.

2 Normative references

The present standard features references to the following standards:

GOST 12.1.005−88 standards System of labor safety. General hygiene requirements for working zone air

GOST 12.4.028−76 System of standards of occupational safety. Respirators SB-1 «Petal». Specifications

GOST 17.2.3.02−78 Protection of nature. Atmosphere. Rules for establishing permissible emissions of harmful substances by industrial enterprises

GOST 380−94 in Steel quality carbon. Brand
________________
* On the territory of the Russian Federation GOST 380−2005. Here and further. — Note the manufacturer’s database.

GOST 859−78* Copper. Brand
________________
* On the territory of the Russian Federation GOST 859−2001. Here and further. — Note the manufacturer’s database.

GOST 977−88 steel Castings. General specifications

GOST 1050−88 hire gauged bars with special surface finishing of carbon structural quality steel. General specifications

GOST 1577−93 rolled sheets and wide strips of structural quality steel. Specifications

GOST 2226−88 (ISO 6590−1-83, ISO 7023−83) paper Bags. Specifications

GOST 2246−70 steel welding Wire. Specifications

GOST 2789−73 surface Roughness. Parameters, characteristics and identification

GOST 3242−79 welded Connections. Quality control methods

GOST 4543−71 rolled alloy structural steel. Specifications

GOST 5520−79 sheet products of carbon, low alloy and alloy steel for boilers and vessels working under pressure. Specifications

GOST 5632−72 high-alloy Steels and alloys corrosion-resistant, heatresistant and heat-proof. Brand

GOST 7566−94 metal Products. Acceptance, marking, packing, transportation and storage

GOST 9087−81 melted welding Fluxes. Specifications

GOST 14637−89 (ISO 4995−78) rolled plate from carbon steel of ordinary quality. Specifications

GOST 14792−80 Parts and blanks, cut out the oxygen and plasma arc cutting. Precision, quality of cut surface

GOST 15164−78 Electroslag welding. Welded connections. Main types, design elements and dimensions

GOST 19281−89 (ISO 4950−2-81, ISO 4950−3-81, ISO 4951−79, ISO 4995−78, ISO 4996−78, ISO 5952−83) rolled steel with increased strength. General specifications

GOST 19903−74 hot-rolled steel sheets. Assortment

GOST 24297−87 Input control products. The main provisions of the

GOST 25054−81 forgings of corrosion-resistant steels and alloys. General specifications

GOST 26131−84 forgings of heat-resistant superalloys. General specifications

3 Definitions

In this standard use the following terms with respective definitions:

3.1 input pocket: a Device for ensuring the start of the welding process ESW.

3.2 lead strap: a Device for output of the slag pool in electroslag welding the end of the seam.

3.3 consumable mouthpiece: a Device for compatmode and direction of feed of the electrode wire; melts simultaneously with the wire in electroslag welding.

3.4 padkamenne: Device holding the flux for secure pocket from burning out at the beginning of the ESW ring seam.

3.5 welding with oscillation of the electrode: welding with the reciprocating movement of the electrode in the gap on the thickness of the seam.

3.6 dry electrode extension: the length of the electrode from the bottom end of the contact mouthpiece to the mirror of the slag bath.

3.7 forming device: a Device that provides forming the outer surface of the seam and the restraint from flowing molten slag and metal in electroslag welding.

3.8 slag bath: the volume of the melted flux for ESW, and limited the welded edges of the workpiece and forming devices.

4 Denote

In this standard the following notation:

 — the thickness of the metal being welded blanks, mm;

 — brew the estimated gap between the welded edges of the workpiece, mm

 — brew the width of the gap between the blanks, mm;

 — the length of seam, mm;

 — the speed of electrode wire feeding, m/h;

 — welding speed, m/h;

 — the voltage of the welding current to the electrode wires;

 — welding current, A;

 — the depth of the slag bath, mm;

 — dry the electrode extension, mm;

 — the number of electrode wires, pieces;

 — distance between electrodes, mm.

 — the total cross-sectional area of electrode wires , cm;

 — the area of the brew gap , cm;

 — the speed of the transverse oscillations of the electrode, m/h;

 — the distance between adjacent electrodes in the time of finding them in opposite extreme positions in the Commission of vibrations, mm;

the minimum distance from the electrode wire to the workpiece edge during its oscillatory movement, mm.

 — the duration of the stop electrode wires from the forming devices;

the cross — sectional area of consumable nozzle , cm;

 — the width of the consumable nozzle, mm;

 — thick plates consumable nozzle, mm;

 — the volume flux, cm.

5 Requirements

5.1 Requirements the main and auxiliary welding materials

Electroslag welding is used for welding steels:

— quality carbon grades St3 and ST5 according to GOST 380;

— quality carbon structural grades 20, 25, 30 GOST 1050; 15K, 20K according to GOST 5520; 15L, 20L, 25L, 30L, 35L according to GOST 977;

— alloy structural grades 09G2S, 16GS to GOST 19281; 35X, 30KHGSA, 35KHM, 20ХНМФ, 20ХНЗМА according to GOST 4543; 20GSL, 08GDNFL according to GOST 977; 16ГНМА, 10ГН2МФА, 15Х2МФА, 08KH18N10T, 12X18H10T according to GOST 5632.

Steel is used in the form of blanks from steel plates forgings and castings.

Put rolled plates of a thickness more than 160 mm in accordance with GOST 14637, GOST 1577, GOST 5520 GOST 19903.

Forgings shall meet the requirements of GOST 25054, GOST 26131.

Castings shall meet the requirements of GOST 977.

Forgings and castings can be delivered by other agreed regulations.

Perform electroslag welding steel electrode wire with a diameter of 3 mm according to GOST 2246.

Before use in the process electroslag welding wire from the coil, when it has the factory label and batch number, it is necessary to rewind the coil and, if necessary, clean wire from the process film, and the end of the wire after winding the insert into the hole on the coil cheek and bend.

Strictly forbidden the end of the wire on the coil to get under the coils to prevent unwinding.

If necessary it is possible to connect the ends of the wire butt welding. The surface must be thoroughly cleaned to the nominal diameter of the wire and marked with white paint to control the passage of the joint in the mouthpiece.

The flux should be dried in a drying Cabinet for 3 to 4 h at the temperature stated in ND, for a specific brand of flux.

The flux transport from the warehouse to the shop floor and the shop should be carried out only in closed containers.

At electroslag welding using fused flux an-8, an-22 according to GOST 9087.

To seal the gaps between the forming device and the welded edges of the blanks using clay.

It is strictly forbidden to use for sealing wet asbestos, as it is a carcinogenic material.

Cooling device, forming the outer surface of the seam, use water from the shop of water supply system with closed cycle of water use.

5.2 Requirements for the preparation of the welded materials and welding materials

The supplied materials are subjected to incoming inspection in accordance with the requirements of GOST 24297.

Before the start of production of rolled plates, forged and cast workpieces must be cleaned from accidental dirt and moisture.

The size of workpieces from sheet metal is determined based on the estimated clearance in accordance with GOST 15164.

Billet, sheet carbon and low alloy steel cut mechanized oxygen cutting.

Permissible surface roughness of the cut and maximum deviations from perpendicularity of the cut for plate thickness up to 100 mm must meet the requirements for the procurement of the 2nd accuracy class according to GOST 14792; when sheet thickness more than 100 mm of individual projections and depressions should not be more than 3 mm deviation from perpendicularity of cut surface should not be more than 4 mm.

The preparation of the edges in the welding of cast and forged workpieces with a thickness of 200 mm or more perform the metal cutting machine tools.

The preparation of the edges to be welded of workpieces made of medium alloy steels carry out metal cutting machine tools.

On cast workpieces profits should not be located in the weld areas.

In cast and forged workpieces the surface for forming the strap cutting are performed with a surface roughness of 125 µm according to GOST 2789 width not more than 80 mm from the edge in the field of welding.

In the blanks from the rolled surface of the strip is cleaned of the slag and burrs by grinding portable sand around.

Edge and at an annular seams perform processing metal flame cutting.

For ultrasonic inspection of a welded joint the surface of the workpiece adjacent to the weld seam width, equal to 1.5 of the thickness of the metal being welded, process, with roughness of 1.6 µm according to GOST 2789.

When forming the weld surface fixed or adjustable water-cooled copper plates, the surface under them is allowed to handle.

Form of groove at the welding areas, and its geometrical parameters according to GOST 15164.

To compensate for the deformation of the welded workpieces and maintaining the welding a predetermined tissue gap last must have a wedge shape expanding upward.

The size of the gap between the welded workpieces shall be as specified in table 1.


Table 1

In millimeters

The thickness of the weld metal	The size of the gap between the edges at the weld
at the bottom of the gap	at the top of the gap at the weld seam’s length
300−1000	1001−3000	3001−5000
30−80	28	30	33	40
81−160	30	33	36	49
161−240	31	35	38	50
241−350	32	37	40	51
351−450	32	39	42	52
Note — the size of the gap should be maintained with an accuracy of ±0.5 mm.

The fixation of the welded workpieces during Assembly carry out brackets and (or) bars.

The design and dimensions of the clamps shall be as given in figure 1. Staples must be made of sheet metal with a thickness of 30−50 mm.

Figure 1 — the Design and dimensions of clamps for fixing the workpieces at ESW

Figure 1 — the Design and dimensions of clamps for fixing the workpieces at ESW

The distance between the straps set of 500−800 mm along the brew of the gap between workpieces.

Bracket and strap are welded to the unilateral corner seams. Sutures should be placed no closer than 80 mm from the edges of the workpieces.

The size of welding of straps and clamps are dependent on the thickness and mass of the welded workpieces and if necessary, transportation of construction Assembly shall be designed with seams for strength.

To start the electroslag process with one end of the brew gap set of the input pocket. For removal of a shrinkage pipe on the other end of the gap set pin strap (figure 2).

Figure 2 — Scheme of ESW live brew of the gap between workpieces

1 — welded workpiece; 2 — entrance pocket; 3 — lead strips; 4 — fixing bracket

Figure 2 — Scheme of ESW live brew of the gap between workpieces

The input of the weld pocket, lead straps, brackets and Assembly brackets to the steel prone to hardening, to produce a heated welding up to 200 °C. To prevent the formation of cold cracks in steel workpieces with the carbon equivalent of 0.5 should electroslag welding with pre-heating of welding. The carbon equivalent of the steel in percent is calculated by the formula

, (1)

where , , , , , , , ,  — the weight content in % of respective chemical elements.

Modes of heating of steels depending on the carbon equivalent shall be as specified in table 2.


Table 2

Carbon equivalent	Welded steel grade (example)	The thickness of the workpieces at the weld, mm	Temperature, °C
preheating of the edges, not less than	the weld joint before landing in the oven after welding, not less	furnace at the time of landing of the product
Not more than 0.5	St3, 20, 09G2S, 15K, 20K, 25, 15L	30−450	Without heating	Without limiting	Without limiting
08GDNFL, 16ГНМА	451−1000	100	100	150−450
0,51−0,60	ST5, 35, 30GSL	30−250	100	100	150
12KHM, 20Х2МА	251−1000	One hundred fifty	150	150−450
0,61−0,70	45, 20ХНМФ, 25Х2ГНМТ, 35KHM	200−1000	200	200	100−450
0,71−11	34ХМТА, 25ХНЗМФА	450	250	250	300−450
Notes 1 Steel 20Х2МА, 16ГНМА, 20ХНМФ, 25Х2ГНМТ included in the respective group table on the basis of practical experience of welding. 2 Steel ST5, Ст35 can be welded without preheat when the thickness of the workpiece in the weld area not more than 100 mm.

The Assembly of the annular gaps brew perform with the help of the centering Assembly of strips and distance strips, fixing the value of the required clearance. For starters ESW in the gap set pocket and padkamenne (figure 3) on the markup.

Figure 3 — diagram of the ESW ring brew gap between the workpieces

Figure 3 — diagram of the ESW ring brew gap between the workpieces

At the point I (bottom pocket) the size of the gap should be minimal ().

In point II of intersection of the radius perpendicular to the line AB, with the outer circumference edges of the welded workpieces, the gap size should be max (). Line ABdrawn through the point of intersection of the seam ring welding seam with the outer circumference edges of the welded workpieces and their center.

At the point /// the size of the gap should be .

The size of the gap between the two edges of the welded ring blanks shall be as specified in table 3.


Table 3

In millimeters

The thickness of the weld metal	The minimum clearance at the point /	The maximum clearance at the point // if the length of the weld
350−1200	1201−2200	2201−3200
30−50	25	29	30	32
51−100	28	32	33	35
101−150	30	34	35	37
151−200	32	35	36	38
201−250	33	37	38	40
251−300	34	38	39	41
301−450	36	41	42	44

Input pocket and padkamenne made of sheet steel with a thickness of 30−40 mm. At the outer circumference of the annular brew gap welded to the billet strap Assembly at a distance of 500−600 mm from each other, the seams must not reach the abutting edges of workpieces 80 mm.

Excess of one edge over another should not be more than 1 mm.

The consumable form of the mouthpiece is determined by the configuration of the brew gap between the workpieces. Melting the mouthpiece is a set of steel plates or bars provided with guide channels with a diameter from 4.5 mm to 5 mm, for feeding the electrode wire with a diameter of 3 mm guiding channels may have a spiral shape wound from a welding wire. The length of the mouthpiece determines the length of the brew gap between the workpieces, taking account of the lengths of the input pocket, the output of the planks and construction of the mouthpiece holder. The length of the mouthpiece from the side edges of the blanks at a distance of from 200 to 250 mm fasten the insulators to prevent electrical current at the enclosure during ESW.

The insulators are made from fiberglass and glass or liquid from a mixture of fluorspar and water glass by ND. The number of electrode wires in the mouthpiece is determined by the formula (2). The resulting value is rounded up to an integer, and again substitute in the formula (2), specifying the value .

. (2)

The thickness of the plate consumable nozzle is selected depending on the distance between the electrode wires according to table 4.


Table 4

In millimeters

The distance between the electrodes in the mouthpiece	The thickness of the plate is melted mouthpiece
50−110	4−6
90−120	8−10

When you install a consumable nozzle in the brew gap lower end of it should be at a distance of 40−50 mm from the bottom of the input pocket. Extreme channels of the mouthpiece should be parallel to the edges of the workpieces and to be at 15−17 mm from the surface.

5.3 requirements to the technological process of welding

Electroslag welding is performed with a tolerance of ±15° from vertical brew gap with forced weld formation and use of AC or DC. The implementation of the whole seam should be implemented without a random (forced) stoppages.

The wire electrode performs a welding rectilinear and circumferential welds when the thickness of the weld metal 30−450 mm.

Consumable mouthpiece perform the welding of straight and curved seams when the thickness of the weld metal 30−3000 mm.

5.3.1 requirements for the composition and sequence of technological operations ESW

5.3.1.1 welding rectilinear seams wire electrodes

Before welding, you need:

— set the welding machine on the brew gap;

— to set the required departure of the electrodes by changing the position of the forming device;

— to verify the accuracy of the movement of the forming devices relative to the brew gap;

— set the apparatus the required plane of movement of the electrodes in the middle of the gap length and adjust the amplitude of the oscillation electrodes;

— move the camera in a pocket so that the electrodes were from the bottom of the pocket at a distance of 110−120 mm, to install and to be clamped to the workpiece forming device;

forming the device on the outside to coat with clay contour fit to the surface of the welded workpieces and to allow the water to cool;

— at the bottom of the pocket to add a layer of metal shavings or grit in the thickness of 10−12 mm, and then a flux layer thickness of 10−15 mm;

— welding machine to bring it into working condition.

Welding is started when the feed speed of the electrode wire is 200−250 m/h After the occurrence of the arc should decrease the wire feed speed up to (150±50) m/h and over 3−4 min to create the required gap depth of the slag bath and to provide a stable electroslag welding process. When you approach the mirror of the slag bath to the upper cut forming device must include a mechanism for vertical movement.

It is necessary to equalize the travel speed of the welding machine with the welding speed of the workpieces.

During electroslag welding is necessary to ensure the tightness of the slag bath.

After the completion of the ESW output electrodes of the slag bath and in 2−3 minutes, remove form the device and stop the supply of water for their cooling.

5.3.1.2 welding of circumferential welds with a wire electrode

Prior to welding products the bottom of the pocket must be positioned horizontally and to install the welding machine to brew clearance. It is necessary to determine the position of the nozzles and the distance between electrodes, the amplitude of the oscillations of the electrodes, the position of the limit switches, the fitting of the shaping device.

The gaps between the edges of the blanks, pocket Pokermania and forming a device seal (daubed) with clay. Between the pocket and Pokermania fall asleep a layer of flux.

If necessary, carry out the preheating gas flame products in the area of the weld-start.

At the bottom of the pocket under the electrodes of the poured iron powder or small chips, then the flux layer thickness of 20−30 mm.

Welding is started, one electrode wire from the top of the mouthpiece. The middle and bottom of the electrode wire include after the formation of the slag bath.

Welding the initial section of the weld and the welding of the pocket lead to the rise of level of molten metal in the bath at the horizontal diameter by lifting a welding machine without rotation of the product. The end pocket is brewed with a stationary unit and a rotating unit.

Welding is started when the feed speed of the electrode wire is 200−250 m/h After the occurrence of the arc reduce the wire feed speed up to (110±10) m/h as the melting flux into the gap pour new portions of the flux to obtain the desired depth of the slag bath.

After the formation of the slag bath sequentially turn on the flow of the middle and lower electrode wires.

If you reduce the dry electrode wires up to 70 mm, it stabilizes the lifting of the welding machine. By increasing the distance between the mouthpiece and the inclined wall of the pocket horizontally and 20 mm include vibrations of the electrodes with a constant increase in their amplitude. The value should be 15−18 mm. Simultaneously with the increase in the amplitude of the oscillations pushing the mouthpieces.

When the level of the slag bath and the upper part of the pocket is 20−30 mm, set and pressed to the welded edges of the front portion of the forming device so that its upper edge towered over the top of the pocket 45 to 50 mm. Clearance between the forming device and the device is compacted (daubed) with clay.

After raising the upper part of the forming device (55±5) mm above the horizontal diameter the further rise of the apparatus is stopped, and include the rotation of the product.

When welding the annular gap periodically check the position of the electrodes in the gap, the welding approach of the electrodes to a forming device, the depth of the slag bath, the seal forming device. The water inlet temperature must not exceed 60 °C at the outlet of the forming device.

After turning the product from 0.3 to 0.4 in turnover in the welding process the initial portion of the seam gas cutting cut out the pattern with the width of the gap 28 to 32 mm.

Before the closure of the seam (figure 4, a) the initial portion heated with gas burners along with a lifting apparatus for closing the seam and finish when the slag bath for the beginning of the seam circuit (figure 4, b).

Figure 4 — diagram of an infusion circuit of the ring weld

Figure 4 — diagram of an infusion circuit of the ring weld

The rotation of the product is discontinued and include the upgrade apparatus when the linear part of the beginning of the seam is vertical position (figure 4, a).

When lifting the machine before the start of the seam controlled by the distance from the electrodes when they stop up forming device. Immediately prior to approach the level of the slag bath to the beginning of the seam, the inner part forming devices along the beginning of the seam lift up to 50−60 mm and gradually reduce the feed speed of electrodes (30±10) m/h without changing the welding voltage.

From the moment of contact of the molten slag bath of the beginning seam as narrowing of the melting area of the mouthpieces together and reduce the oscillation amplitude of the electrodes.

After welding the vertical part of the seam started lifting apparatus is stopped, and include the rotation of the product. With decreasing oscillation amplitude of the electrodes reduces the voltage at (4±1) To reduce the feed speed of the electrode, providing a welding speed of 0.3−0.35 m/h.

When the amplitude decreases to 30 mm lower electrode is removed from the work, stopping its flow and setting for the product over a forming device, a transverse metal bar for the hot electrode, if the electrode when the reciprocating movement (figure 4, in) reaches the strap.

After the withdrawal of the lower electrode, the distance between the middle and top electrodes increase from 55 to 85 mm (figure 4, g) and clarify the approach of the electrodes to a forming device. With decreasing melting area is removed from the working medium output electrode similar to bottom electrode (figure 4, d). Increase the voltage to (6±1) and the feed rate of the upper electrode (50±10) m/h by adjusting his approach to the forming device (figure 4, e). After (4±1) min start to lower the voltage and wire feed speed.

When reducing the melting area to the vibration of the electrode is stopped and the welding is continued until the loss of stability of the electroslag process, then the process is terminated, and the remaining small cavity brew manual welding.

5.3.1.3 welding consumable mouthpiece

Before welding connecting the welding machine and placed in the brew gap pocket electrically isolated from edges of workpieces melting the mouthpiece, run the wire in the melting channels of the mouthpiece. At the bottom of the brew gap pocket poured the steel powder, grits or swarf. The layer of shavings fall asleep 20−30% of the total flux and brew a gap closing device for the formation of the weld surface. Designated slack forming devices to the surface of the welded workpieces clay-daubed. As forming devices use composite copper water cooled lining.

Start welding all electrodes, or alternately introduce them one at a feed speed of 150−170 km/h. the open circuit Voltage of the power supply should be 48 to 50 V. After establishing a stable arc process, the wire feed speed is reduced to (95±5) m/h, to fill up the gap flux.

After the formation of the slag bath to the required depth, the feed rate of the electrodes is increased to the calculated, check the voltage of welding and post weld work pieces.

During spontaneous stopping of wire feed her resume when melting the bottom of the mouthpiece of the slag bath.

5.3.2 Requirements for modes and parameters of ESW

ESW perform one, two or three electrode wires.

The distance between wires , mm, is determined by the formula

. (3)

Value  — 17−18 mm. the Value of 4−5 mm at the depth of the groove formed in the slide device from 1 to 2 mm When the depth of the groove in the slide 8 to 10 mm 0.

Speed welding voltage welding current to the electrode wires, the number of electrode wires shall be as specified in table 5.


Table 5

Thickness of welded edges of blanks, mm	The number of electrode wires		The voltage of the welding current,	Welding speed, m/h
with the vibrations of the wires	without hesitation wires
30−40	1	1	43−44	2.0 to 2.5
41−50	1	1	44−45	1,5−1,8
51−100	1	2	45−48	1,0−2,0
101−150	1	3	46−50	0,7−1,0
151−200	2	-	48−50	0,6−0,8
201−300	2, 3	-	50−52	0,5−0,7
301−450	Three	-	50−55	0,4−0,6

The depth of the slag bath during electroslag welding of any thickness of metal should be 40−50 mm; length of the dry electrode wire — 80−100 mm; the speed of the transverse oscillations of the electrode wire brew gap should be 40 km/h; the stopping time of the electrode wires from the slide — 4−5 p.

The arrangement of electrode wires in the brew gap at electroslag welding with transverse oscillation should match figure 5.

Figure 5 — scheme of an arrangement of electrode wires in the brew gap at electroslag welding with transverse oscillation

Figure 5 — scheme of an arrangement of electrode wires in the brew gap
at electroslag welding with transverse oscillation

Speed of electrode wire feeding , m/h, determined by the formula

. (4)

The welding current , And one electrode wire is determined by the formula

. (5)

Speed of electrode wire feeding , m/h, welding consumable mouthpiece is determined by the formula

. (6)

Electroslag welding with consumable nozzle welding speed and voltage of the welding current on the mouthpiece should be as specified in table 6.


Table 6

The thickness of the welded materials, mm	Welding speed, m/h	Critical speed of electrode wire feeding, m/h	The voltage of the welding current on the mouthpiece,
when (5±1) mm	at (9±1) mm
30−60	1,0	170	43−44	40−42
61−100	0,70−0,80	160	44−45	42−43
101−200	0,60−0,65	140	44−45	43−44
201−400	0,50−0,55	130	45−46	44−45
401−800	0,45−0,50	120	46−47	45−46
801−1000	0,40−0,45	110	47−48	46−47
1001−2000	0,30−0,35	110	48−50	46−47
2001−3000	0,28−0,30	110	48−50	47−48

The feed speed of the electrode should be not more than the critical values given in table 6.

Total welding current And is determined by the formula

. (7)

The required amount of flux , cm, is determined by the formula

. (8)

5.4. The requirements for the basic and auxiliary technological equipment

To perform electroslag welding welding requires the following equipment:

— a set of welding apparatus with a welding power source;

device for fixing (movement or rotation) of the welded workpieces;

device to move along the brew gap welding machine and (if required) the welder-operator.

5.4.1 Requirements for the main process equipment

The basic equipment consists of a welding machine with control system and power source.

At electroslag welding electrode wire welding machine must provide:

— feeding the electrode wire into the welding zone at a given speed;

— move the camera up along the seam with the welding speed;

reciprocating movement of electrode wires in the brew gap between the workpieces;

— move the water-cooled slide forming devices to force the formation of the outer surface of the welds.

The feed rate of the electrode wire adjust, usually from 65 to 480 m/h.

The travel speed of the welding machine while welding adjust from 0.15 to 9.0 m/h.

Welders for electroslag welding with consumable nozzle feed speed of the electrode wire adjust from 14 to 306 km/h.

Power supply AC or DC for the ESW must have a hard or flat-dipping feature and the possibility of voltage regulation under load.

The equipment should provide a welding without forced stops.

5.4.2 Requirements for assistive technology equipment

Accessories at electroslag welding provides installation and moving of workpieces before welding and in the welding process the weld, mounting and moving the welding machine, the ability to service the welding zone.

Assemble pieces and install them in a convenient welding position is performed on universal and specialized Assembly and welding stands. When welding circumferential welds for rotating the articles at a speed of welding using roller stands and lateral rotators.

Allowed to use roller stands with driven rollers.

For mounting and moving the welding devices are used in rail columns, carts and portals. For maintenance areas welding welder operator if necessary, use a lifting platform.

5.5 Requirements for process a snap

At electroslag welding technological tooling include forming devices: slides, fixed (adjustable) lining for shaping the outer surface of the weld, the device for fixing, the front pockets off plates.

Forming devices (slides) should fit snugly to the surface of the welded edges to prevent leakage of the brew gap, liquid slag and metal.

Sliders and pads are made of copper grades M1 and M2 according to GOST 859. Their working surfaces should meet the requirements of GOST 15164.

To ensure the required heat sink forming devices have channels for the flow of cooling water.

The length of the fixed lining is determined by the length of a welded seam.

Adjustable pads are used with a length of 250−350 mm. For a good snug fit to prevent leakage of slag in the adjustable plates at the top and bottom make the bevels at an angle of 45°.

For mounting linings use wedges and l-shaped bracket of sheet with a thickness of 10−15 mm. Bracket welded depending on the surface condition and configuration of the suture through (370±130) mm.

Input pocket and lead strap are made of steel sheet with a thickness of 50−100 mm.

The input pocket and the lead strap, together with a forming device to retain the slag bath at the beginning and completion of the ESW.

5.6 Requirements for functional control

Functional control is carried out in all process steps from electroslag welding of workpieces to the Department of primary pockets and pin bars.

In the welding process check:

— welding voltage;

— the welding current;

— the depth of the slag bath;

— feed speed of the electrode wire;

— welding speed;

— the distance at which approaching the electrode to a forming device when the reciprocating moving it along the gap;

— the position of the electrode relative to the abutting edges;

value of dry electrode extension;

— the temperature of the water in the forming device;

— quality of surface seam.

The welding voltage and the welding current control the voltmeters and ammeters (accuracy class 0.5).

The control voltage values of the welding and the welding current is carried out continuously (recorders) or periodically through (7±3) min at the beginning and at the completion of welding and using (25±5) min for the linear part of the seam.

Control the depth of the slag bath is carried out using a mechanical probe (25±5) min (at ESW with slides).

Speed of electrode wire feeding control of periodically through (7±3) min the number of revolutions of the feed roller per unit time.

Welding speed is controlled by the number of completed chalk lines in a unit of time, plotted along the brew gap of 0.5 m.

The position of the electrode within the weld gap control with an accuracy of ±3 mm.

Water temperature in forming the devices should not exceed 60 °C.

Welded joints, electroslag welding is performed, is subjected to complex control, including visual inspection, ultrasonic flaw detection (only after high temperature treatment) or radiation control (x-rays, -rays) in accordance with GOST 3242.

Visual inspection reveals surface defects: lack of fusion, undercuts, cracks, pores, sagging.

Ultrasonic testing detects defects inside the welded joints: stratification, lack of fusion, undercuts, slag inclusions, pores and cracks of any orientation for any thickness of the weld metal.

Radiation method allows to detect the same defects in Shrivenham limited metal thickness: x-rays — up to 70 mm . to 250 mm.

5.7 performance Requirements of the workplace and production facilities

Plot for ESW must be located in a well-ventilated area, volume and area according to sanitary norms.

The parcel must be in the immediate vicinity of heat-treatment furnaces or devices by local heat treatment. It is desirable that the complex ESW and thermal furnaces were in adjacent spans of the same plant.

Welding machines (stands) should be located at the end of the passage or about the Guild columns. This requirement is necessary to exclude the transportation of goods shop cranes over the installation or machine during their work.

The area should be located posts for manual arc welding and gas cutting machine, cleaning and coiling of the welding wire, switchgear water supply and drain waste water, the device of independent water supply device for pre, concomitant and subsequent heating of the welded materials. The plot should be placed within range of shop crane with sufficient capacity.

Food plot electricity should be primarily from a separate distribution Board with capacity of 500 or 1000 kV·A.

5.8 Requirements for products received ESW

Welded joints, electroslag welding is performed, must provide the service characteristics set design documentation and the reference document on the product and agreed with the customer.

In case of detection of inadmissible defects of the welded connection can be repaired. Method of repair (removal of the defect, welding, subsequent thermal and mechanical treatment) is appointed in accordance with the process developed by the company performing the repair.

Defects in welds shall be completely removed by mechanical means, and the resulting cutting welded.

5.9 labelling Requirements of products

The marking shall be as defined in the design documentation or normative document for the products. Markings shall be performed in accordance with GOST 7566.

5.10 Requirements for transportation and storage

5.10.1 transportation Requirements

Requirements for transportation of rolled products and downstream products — according to GOST 7566.

Requirements for the transportation of castings and forgings set in the RD and ND for these products. Fluxes should be transported Packed in paper bags according to GOST 2226, net weight per bag is 20−50 kg.

Welding wire should be transported in coils weighing up to 80 kg. By agreement with consumer it is permitted mass bays more than 80 kg.

5.10.2 storage Requirements

Storage requirements rental and products further processing — according to GOST 7566.

Storage requirements castings set in the RD and ND for casting.

Storage requirements forgings — GOST 25054, GOST 26131.

Storage requirements for flux — according to GOST 9087.

Storage requirements of the welding wire according to GOST 2246.

5.11 Requirements for industrial hygiene and safety

At electroslag welding of large workpieces with preheating parameters of the microclimate at the working places of welders shall conform to the requirements of SN N 4088 [1]. Working zone of the welder must be escaped with a supply of cooling air.

Balcony welder specialized installation for electroslag welding of workpieces with a thickness of 1000−3000 mm shall be equipped with thermally insulated cabin with conditioned air.

The content of harmful substances in the air of working zone at electroslag welding shall not exceed maximum permissible concentrations (MPC) according to GOST 12.1.005. The room where electroslag welding is performed, must be equipped with General dilution ventilation in accordance with SP 1009 N [2], as well as devices local exhaust ventilation.

Control of content of harmful substances in the air of working zone of the welder must be carried out in accordance with the requirements of 4945 N SN [3] on the main harmful components of welding fumes: fluoride of manganese, silicon, iron, titanium, hydrogen fluoride, carbon monoxide, ozone and nitrogen oxide.

If the existing in the production area ventilation system does not provide decrease these harmful substances by the MPC, then additional respiratory protection welder it is recommended to use respirators SB-1 «Petal» according to GOST 12.4.028.

5.12 Requirements for environmental protection

At electroslag welding of workpieces for atmospheric air protection from pollution emitted harmful substances should be provided for activities in accordance with the requirements of GOST 17.2.3.02.

Waste disposal main and auxiliary welding materials should be in accordance with the requirements of GOST 380, GOST 977, GOST 2246, GOST 5632, GOST 9087.

For the protection of the environment by the use of electroslag welding should:

— use independent water supply system with closed cycle of water use for cooling with water the seam forming device;

— apply an exhaust device (local and shared) to trap and clean the air of harmful pollutants produced by electroslag welding.

5.13 requirements for the qualification of welders

To perform work-related equipment and technology ESW, allowed welders who have received special courses necessary theoretical and practical training and certified not below the fourth qualification category according to the current normative document.