Some standard content:
Machinery Industry Standards of the People's Republic of China
General technical conditions for electroslag welding
Subject content and scope of application
JB/T 6967-93
This standard specifies the wire electrode electrode Requirements for roughness of slag welding and melt nozzle electroslag welding, general principles for welding assembly, welding materials and welding parameter selection and welding process control.
This standard applies to wire electrode and single nozzle electroslag welding of carbon steel and low alloy steel (steel castings, forgings and rolled plates) with carbon content ≤0.5%. This standard does not apply to electroslag surfacing
2 Reference standards
GB1184 Shape and position tolerances without tolerances 3 Electroslag welding process characteristics
The electroslag welding process method is Welding relies on the resistance heat generated when an electric current passes through a pool of liquid slag to melt the filler metal and base metal. However, the establishment of the liquid slag pool must first rely on arc heat, so it is necessary to master the rapid conversion from the arc arc process to the electroslag process.
4 Commonly used joint forms for electroslag welding
Commonly used joint forms for electroslag welding are shown in Table 1. Other specific joints can also be used, which can be selected by the enterprise according to structural requirements. Table 1
Applicable thickness
mm
Weld name
Pair
Connection
Pad butt connection
Right angle connection
Basic type
Weld form
The Ministry of Machinery Industry of the People's Republic of China approved 426 on 1993-07-27
Wire pole
Single wire to|| tt | ||Melting nozzle
120
120
120
Preparation
Note
Unequal thickness plates are butted to ||tt| |Thin plate shall prevail
For corner joints of unequal thickness plates, thin
plate shall prevail
Implemented on 1994-07-01
Weld name
Miter joint
Corner joint with backing plate
T-shaped connection
T-shaped joint with backing plate
Basic type
Note: 1) Straight seam , universal for circumferential seams.
2) Universal for plate-shaped melting nozzles and tubular melting nozzles.
5 General technical conditions for wire electroslag welding
5.1 Selection of welding wire and flux||tt ||5.1.1 Selection of welding wire
JB/T 6967-93
Continued Table 1
Welding seam form
Wire electrode
Applicable thickness| |tt||mm
Melting tip
Single
Single wire to
Three wires\
16300
16~~450| |tt||16~-450
16~400
pieces
melt
mouth”
80
120||tt ||120
120
Prepare
Note
1) Unequal thickness plate shape
connection, subject to thin plate
2 )Wire electrode electroslag welding
requires the machine head to be close to the weld.
Enable the contact tip to enter the human world
Medical
The selection of welding wire is mainly based on the material and design requirements of the workpiece to be welded (equal strong matching and unequal strong matching), for approximately equal strong matching Refer to Table 2 for welding wire selection. When welding base metals of different strengths, the welding wire can be selected according to the low-strength base metal. Table 2
Base metal model
Q235
20, 25.20g
16Mn 16MnR 25Mn
35, 40.45
20MnSi||tt ||15MnV
Welding
H08MnA H08A
H10Mn2H08MnA
Wire
H08MnMoA H10Mn2
HIoMnSi
H10Mn2 H08Mn2Si|| tt||H10Mn2H10MnSi
H08Mn2SiA
Prepare
H, German steel number
SM50BH Benxi steel number
19Mn6 German steel numberbzxZ.net
Note
427
-
base metal model
15MnVN
18MnMoNb
00Cr13Ni5—6Mo
5.1.2 flux Select
JB/T 6967-93
Continued Table 2
Welding
H08Mn2MoV
H10Mn2MoVA
H10Mn2NiMoA
H12CrMo
H00Cr17Ni6Mo
Wire
Prepare
SA204B American steel number
Note
13MnNiMo54 German steel number
13CrMo44 German steel No.
The main function of flux is to melt into a slag pool as a heat source. Usually HJ431 can be used for electroslag welding. When there are special requirements, it will be selected by the process.
The influence and selection of welding parameters
5.2
5.2.1 Principles for formulating welding parameters
5.2.1.1 The electroslag process has good stability. '5.2.1.2 No welding defects will occur and the joint quality will be good. 5.2.1.3 Improve the overall performance of welded joints. 5.2.1.4 Control the welding deformation of the structure.
5.2.1.5 Improve productivity as much as possible.
From the perspective of metallurgy and controlling weld crystallization, the weld forming coefficient must be controlled: β-B/H .
where:
B-
H-| |tt||Weld forming coefficient, usually 9-24; molten pool width:
molten pool depth.
In practical applications, welding speed is also commonly used to select welding specifications. - General low carbon steel: U welding = 0.7~1.2m/h;
Medium carbon steel and low alloy steel: drying = 0.3~0.7m/h. 5.2.2 The influence of main welding parameters on the forming coefficient and slag pool stability and the recommended welding parameter control range are shown in Table 3. Table 3
welding
form
shape
parameter
connection
number
H
8
Melting of base metal
Slag pool stabilization
Recommended specifications
Note:
parameters in the table
Number
Send Wire speed
Welding current
≤200m/h
400A
+ year
++
+
*
≥200m/h
≥400A
, string
++
++
++
400 ~500A
increased abundance
++less grease
+ not significant increase
+less alkali not significant
selection of wire diameter and number of wires| |tt||5.2.3
428
When the welding parameters increase
Welding
Voltage
Feng
++|| tt||+ +
++
+
400~50V
Welding wire
Hold
Speed
++
++
++
40m/h
Slag pool
Depth
+
++
?++
++
40-~60mm
Welding wire
Dry extension
Length
★+
+
40--70mm
Weld
(1)
Gap
Feng Chuan
Chuan Chuan
28-36mm
5.2.3.1 The diameter of the welding wire is generally $3mm.
JB/T 6967—93
5.2.3.2. The selection of the number of welding wires depends on the thickness of the workpiece to be welded and whether welding wire swing is used (see Table 4). Table 4
Number of welding wires
1
2
3
Welding wire does not swing
60
Workpiece to be welded Thickness
Welding wire lateral swing
60~100(150)
70~100(120)
130~180(220)
Note: Table The middle is the recommended value, and the brackets are the maximum thickness that the equipment can weld. 5.2.4 Selection of other parameters
The time the welding wire stays next to the cooling slider is generally selected from 3 to 6 seconds. 5.2.4.1
5.2.4.2
5.2.4.3
5.2.4.4
The distance between the welding wire and the cooling slider is generally 8~12mm. When multi-wire welding is swinging, the non-overlapping distance between the two welding wires is generally selected to be 20~30mm. The outlet water temperature of the cooling slider is generally selected from 40 to 50°C. 5.3. Straight seam electroslag welding
5.3.1 Requirements for rough hair
5.3.1.1 The rough hair should have a material report sheet, and its chemical composition and mechanical properties should comply with standards or design requirements. 100-240(300)
180-~400(450)
mm
2 Rust, oil and other dirt within 50mm of both ends of the joint and near the seam area should be removed , the forging should be processed within 100mm on both sides of 5. 3. 1. 2
, and should comply with Class B in GB1184. 5.3.1.3 Castings should be sand cleaned. The riser area of ??steel castings cannot be used as the end face of the welded joint. The chemical composition of the joint end face must be ensured to be uniform. If the design requires weld flaw detection, the rough end face and the 100mm on both sides of the end face must also be inspected. It should be inspected for flaws and there should be no excessive defects. 5.3.2 Assembly
Assembly and its clearances are shown in Figure 1 and Table 5. For every 1m increase in weld length, the assembly gap should be increased by 1.5 to 2mm. The assembly misalignment shall not exceed 2mm. When using the movable cooling slider, the misalignment shall be controlled within 1mm. Figure 1 Straight seam electroslag welding assembly
One lead-out plate; 2-workpiece: 3-positioning plate; 4-arc plate Table 5
Thickness of welding end face
Assembly room drying| |tt||30-60
28
61~100
30
101~150
32
151~200| |tt||33
201～300
34
mm
301~400
35
429
JB/T6967-93
The arc groove height is 150mm, the width is the same as the welding end face, and the thickness is ≥60mm. The material should be as consistent as possible with the parent material. The height of the lead-out plate is 100mm, and the width is the same as the thickness of the welding end face, 80mm. The material should be as consistent as possible with the base material. The dimensions of the positioning plates are as shown in Figure 2. The material is Q235 and the thickness is 30~50mm; the spacing between the positioning plates is 800~1000mm. The positioning plate can be used repeatedly. || tt | The welding equipment should be able to operate normally, and the electroslag welding process should not be interrupted to meet the needs of long-term operation and ensure continuous power supply. The water supply system should be smooth.
Check auxiliary tools and materials to ensure usage requirements. 160 | Wire arc ignition, the arc ignition voltage should be 2~4V higher than the normal welding voltage, and the wire feeding speed should be 100~120m/h. After arc ignition, flux is added to create slag, and a normal slag pool is gradually established. In multi-wire welding, the remaining welding wires should be given away as soon as possible after arc ignition and slag formation, and transferred to normal welding specifications as soon as possible. Any other suitable method can also be used to induce slag. 5.3.3.3 Welding
must maintain the stability of the welding specifications and the stability of the slag pool. The welder should pay attention to adjusting the position of the welding wire in the interface gap, measuring the depth of the slag pool, and observing the swing of the welding wire. When slag leakage occurs, it should be blocked with asbestos mud in time. If the slag leakage is serious, the wire feeding speed should be reduced and the voltage should be increased to restore the stability of the electroslag process in a timely manner. If the welding process is interrupted, the shrinkage of the workpiece must be controlled, and appropriate methods must be used to re-introduce slag and resume the welding process. As the slag pool rises and the weld seam forms, the positioning plate should be cut off in time. 5.3.3.4 Ending of lead-out plate welding
When the molten slag rises into the lead-out plate, the welding voltage and wire feeding speed should be appropriately reduced. Before stopping, power should be supplied intermittently to fill the molten pool and prevent shrinkage holes. During the welding process Do not let go of the slag after stopping. After solidification, cut off the lead-out plate while it is hot. 5.4 Circumferential electroslag welding
5.4.1 Requirements for roughness
5.4.1.1 Forgings and castings shall be treated for roughness according to heat treatment process requirements. The flaw detection shall be carried out within 100mm from both sides of the welding section. . 5.4.1.2 The concentricity of the inner and outer diameters of the welds should be controlled within 1mm. The absolute value of the tolerance of the inner and outer diameters at both ends of the interface is not greater than 2mm. 5.4.1.3 Other requirements are the same as those for straight seam electroslag welding. 5.4.2 Simplified assembly
The circumferential electroslag welding components include: press working cylinder, main machine plunger, reel, various tanks or hollow shafts, etc., now collectively referred to as cylinder. 5.4.2.1 Simplified assembly can be installed vertically or lying down depending on the condition of the workpiece. 5.4.2.2 Use gap pads for cylinder assembly to control the assembly gap, which can be three-point or four-point. The average gap is shown in Table 6. When considering the angular deformation of ring seam electroslag welding, the difference between the minimum gap and the maximum gap is generally controlled at 4mm. 430
Simplified wall thickness
Average gap
60~100
31
JB/T 6967--93
Table 6| |tt||101150
32
151~250
33
mm
251-400
34
5.4.2.3. Simplified connections can use positioning plates or gap pads. The positioning plate is used, its dimensions are shown in Figure 2, and it is usually connected with 4 pieces; the gap is generally used when the simplified weight is less than 30t.
pad, its size should be 100mm×40mm, and the welding leg size should be greater than 15mm. For workpieces with high rigidity and serious crack tendency, preheating assembly should be considered. 5.4.2.4 Before assembly, the arc trough should be installed, usually bucket type, as shown in Figure 3. The retaining irons on the arc ignition slot are decorated one by one during the arc ignition and slag making process until a normal slag pool is established. The arc ignition position should be selected near the minimum gap. 5.4.2.5 The arc strike height is usually on the horizontal axis. In order to reduce the geometric size of the lead plate and reduce the workload of the final gas cutting lead plate, the arc strike height can be appropriately increased.
5.4.3 The entire simplified body is on the roller assembly. 5.4.3.1 The roller should be driveable. If it cannot be driven, an additional driving device should be attached. 5.4.3.2 The cylinder is adjusted on the roller as shown in Figure 4. In order to make the horizontal component and vertical component of the force acting on the roller equal, the central angle should be controlled to 90° as much as possible, especially for major components.
Install rollers on the cylinder and run for one week. The axial movement should be <5mm. Iron retaining
90--120
Figure 3 Arc trough
5.4.4 Welding
5.4.4.1 Who prepares before welding
Figure 4 Simplified The assembly on the roller
The preparation before circumferential seam electroslag welding is basically the same as that of straight seam electroslag welding. In addition, the rotary drive system must be additionally inspected, and the lead-out plate and cutting template must be prepared.
The ruler section of the lead-out plate is as shown in Figure 5, with a thickness of 100mm: the geometric dimensions of the cutting template are as shown in Figure 6, with a thickness of 1mm. 431
0
#+10
Figure 5 lead-out board
JB/T 6967--93
001+-8 *g||tt ||a-wall thickness
Figure 6 cutting template
If the lead-in height is increased, the lead-out plate and cutting template must be manufactured separately. Mass production of simplified copper lead-out plates of the same diameter is available. 5.4.4.2 Arc slag making
Arc slag making is basically the same as straight seam electroslag welding. First, install the inner (outer) slider, and start ignition from close to the inner (outer) diameter. The voltage should be The welding voltage is 2V higher. As the slag pool expands, start to swing the welding wire and feed the second welding wire. As the cylinder rotates, the slag pool expands and decorates the arc stop iron one by one. Then feed the third welding wire and install it in time. The outer slider finally completes the slag making process, see Figure 7. Outer slider
Inner slider
Learning
Illustrated diagram of the bay building process
5.4.4.3 Normal welding
During the normal welding process, it is necessary to keep the welding specifications stable and the slag pool stable. When the workpiece rotates, the spacer (or positioning plate) should be cut off in time. When the welding reaches 1/4 of the circumferential seam, start cutting off the arc groove and the nearby unpenetrated parts: as shown in Figure 8, the unevenness of the cutting surface should be within Within the range of ±2mm, and the residue and scale must be removed. The gas cutting work is carried out according to the template, and the prefabricated lead-out plate is immediately installed and welded after the gas cutting is completed.
If the welding process is interrupted, the shrinkage and deformation of the simplified body should also be controlled, and appropriate methods should be used to re-establish the electroslag process. 5.4.4.4 Welding finishing
When the cutting line turns to be perpendicular to the horizontal axis, it stops rotating. At this time, the welding machine is used to rise to weld the straight seam. Pay attention to adding strips of iron stoppers outside the lead-out plate one by one.
At this stage, the voltage should be increased by 1 to 2V, and the inner diameter welding wire should be as close as possible to the cutting line, controlled at 6 to 10mm. In order to prevent cracks, the welding current should be appropriately reduced. After the workpiece is welded, the feed speed can be reduced. Wire speed and welding voltage. After welding, the lead plate can be cut off when it cools to 200~432
300℃. As shown in Figure 9. Cut off the part
Picture 8 Cut off the arc groove
6-nozzle electroslag welding
JB/T6967—93
Small stopper
Cutting torch
Figure 9 Welding connection and lead-out part
In addition to the welding wire, the melting electrode of melt tip electroslag welding also includes a melt tip fixed in the assembly gap. In addition to being a filler metal to adjust the chemical composition of the weld In addition, it also acts as a conductor and guide wire. The equipment for melting tip electroslag welding generally only needs to complete the feeding of the welding wire. 6.1 Single-plate melt nozzle electroslag welding (excluding large-section and variable-section nozzle electroslag welding) 6.1.1 Single-plate melt nozzle electroslag welding, as shown in Figure 10. Figure 10 Schematic diagram of single-melt electroslag welding
1--Welding wire; 2--Melting tip: 3-Melting tip holder: 4-Finishing plate: 5 workpiece; 6-Insulating pad + 7-Leader Arc plate +8-cooling slider 6.1.2 Melting nozzle manufacturing
6.1.2.1 The melting nozzle is welded by the lath and the guide wire tube. Generally, the thickness of the lath is 10mm, and the guide wire tube should be $10mm. The length of ×2.5mm seamless steel pipe is determined by the size of the workpiece to be welded. The structure is shown in Figure 11. The material of the melt nozzle strip should be determined according to the design requirements for the performance of the welded joint.
433
JB/T 6967—93
@?
a) Double wire fuse
o
b) Single wire Melt nozzle
Figure 11 Melt nozzle structure
1 positioning connection weld; 2-slat; 3-guide wire tube 6.1.2.2 The nozzle plate and steel pipe should be free of oil stains, and the tube and plate are required Symmetrical intermittent welding, the weld length is 50mm, and the melt nozzle should be straight after welding. 6.1.3 Assembly
6.1.3.1 Dimensions of positioning plates for assembly, as shown in Figure 12. The distance between positioning plates is 800~~1000mm. 160
8
460
a straight seam positioning plate
Thickness: 30, material: Q235
Figure 12 positioning plate
6.1 .3.2 The assembly gap is 28~35mm, and anti-deformation must be reserved. 310
0
160
b fillet weld positioning plate
6.1.3.3 The melting nozzle is installed in the middle of the gap (the corner joint is on the side of the thick plate), And fix the melt nozzle on the clamping mechanism, taking care to prevent short circuit between the melt nozzle and the workpiece.
6.1.3.4 In order to facilitate observation of the welding process and measurement of the depth of the slag pool, the height of the slider should be 200~300mm. 6.1.4 Selection of welding parameters
6.1.4.1 The specification parameters of melt tip electroslag welding mainly include: wire feeding speed, slag pool depth and welding voltage. The wire feeding speed is generally controlled below 100m/h. Depth of slag pool: 30~~50mm.
Welding voltage: 40-48V, this is the voltage near the slag pool, the voltage drop on the melting nozzle must be considered. 6.1:4.2 The welding speed is mainly related to the wire feeding speed, and other parameters are relatively certain values. Therefore, when selecting the welding parameters, first select the welding speed. Then convert to the wire feeding speed:
U dry (F-F) /MF wire
where: w welding - welding speed, m/h;
(2)
- general: low carbon reduction = 0.7~1.2m/h; medium Carbon steel V drying=0.35～0.6m/h=Low alloy steel U drying=0.3～0.7m/h434
7m/h434
7m/h434
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