Steel bar electroslag pressure welding
1 scope
The technology standard is applicable to industrial and civil construction in the cast-in-place reinforced concrete structure Ⅰ 14 ~ 40 mm in diameter to Ⅱ vertical or diagonal (tilt 4:1) reinforcing bar connection.
2 construction preparation
2.1 material and main equipments:
2.1.1 reinforced: reinforced level, diameter must comply with the design requirements, have the factory certificate and retest report. Imported steel shall also have the chemical second-round exam list, its chemical composition should meet the requirements of welding, and shall have the solderability test.
2.1.2 flux.
2.2.2.1 flux performance shall comply with the terms of GB5293 carbon steel submerged arc welding with flux. Flux models for HJ401, commonly used for smelting high manganese manganese in high silicon low fluoride flux or high silicon low fluoride flux.
2.1.2.2 flux should be stored in dry warehouse, prevent to be affected with damp be affected with damp. If be affected with damp be affected with damp, before use must be approved by 250 ~ 300 ℃ for 2 h.
2.1.2.3 use recycling flux, should remove slag and sundry, and should be evenly mixed with the new flux used.
2.1.2.4 flux should be the factory certificate.
2.1.3 main machines:
2.1.3.1 manual electroslag pressure welding equipment including: welding power source, control box, the welding jig, flux tank, etc.
2.1.3.2 automatic electroslag pressure welding equipment (preferred) including: welding power source, control box, box operation, welding head, etc.
2.1.3.3 welding power source. Steel bar electroslag pressure welding appropriate USES secondary high no-load voltage (TSV) of ac or dc welding power source. (32 mm diameter and the following general steel welding, the welding power supply capacity of 600 a can be used; more than 32 mm diameter and steel welding, the welding power supply capacity should be adopted for 1000 a). When the welding machine capacity is small, also can use smaller capacity of the same model, with the performance of the two parallel machine.
2.2 operation conditions
2.2.1 welder must hold a valid welder examination certificate.
2.2.2 equipment should comply with the requirements. Welding jig should have enough stiffness, under the maximum allowable load should be mobile and flexible, easy to operate. The diameter of the solder pot, ADAPTS to the rebar diameter welding does not burn out in the welding process. Voltmeter, time display should be equipped so that the operator grasp accurately the welding parameters.
Then the power should comply with the requirements. When the power supply voltage drop is greater than 5%, it is unfavorable to welding.
2.2.4 job site shall have security protection measures, formulate and implement the safety technical measures, strengthen labor protection welders, prevent burns, electric shock, fire, explosion and burning machine.
2.2.5 note joint position, pay attention to the same extent in joint reinforced area percentage, does not conform to the concrete structure engineering construction and acceptance standard "regulations on terms, to adjust the joint position before welding.
3 operation process
3.1 process:
Check equipment, power supply - reinforced end preparation - choose to installation of welding jig and reinforced, welding parameters
Put the wire ball (or save) - put flux irrigation, flux filled - try welding, a specimen to determine welding parameters,
Welds - recycling flux to unload jig, quality inspection
3.1.1 electroslag pressure welding process:
Closed circuit to arc, arc power to electroslag process, extrusion process
3.2 check equipment, power supply, ensure the normal state of the at any time, it is strictly prohibited to overload.
3.3 bar end preparation:
Prior to installation, welding parts and steel electrode jaw contact (150) mm segment of steel on the surface of a rusty spot, oil pollution, sundry goods and so on, should be clean, reinforced side if there is bent, and twisted, must be paid to the straightening or resection, but shall not use the hammer straightening.
3.4 choose welding parameters:
Steel bar electroslag pressure welding welding parameters mainly include: welding current, welding voltage and welding current time, see table 4-23.
Different diameter steel welding, according to the small diameter steel bar to select parameters, welding current extended by about 10%.
3.5 installation of welding jig and reinforced: fixture clamping jaw under next reinforced end position, generally for 1/2 flux tank height below 5 ~ 10 mm, to ensure that the soldering flux has enough YanMai depth.
After reinforcement into the fixture on the jaw, alignment, the starting point of the moving clamp, the fluctuation of steel welding parts in coaxial state,
Steel bar electroslag pressure welding welding parameter table 4-23
Steel welding welding voltage (V) welding current time (s)
The diameter of
(mm) current
(A) arc process
U2-1 electroslag process
U2-2 arc process
T1 electroslag process
t2
16, 200 ~ 200 40 ~ 45 22 ~ 27 14 April
18 250 ~ 250 40 ~ 45 22 ~ 27 15 May
20, 300 ~ 300 40 ~ 45 22 ~ 27 17 May
22 350 ~ 350 40 ~ 45 22 ~ 27 June 18
25, 400 ~ 450 40 ~ 45 22 ~ 27 June 21
28 500 ~ 550 40 ~ 45 22 ~ 24 June 27
32, 600 ~ 650 40 ~ 45 22 ~ 27 July 27
36, 700 ~ 750 40 ~ 45 22 ~ 27 thirty eight
40, 850 ~ 850 40 ~ 45 22 ~ 27 to 33
Before clamping bar.
Reinforced once clamping, beware of shaking, in order to avoid deformation of reinforced dislocation and fixture.
3.6 arc was laid with wire ball (also). Fill in solder flux tank, was laid.
3.7 test weld, as a specimen, determine welding parameters: before the formal for steel bar electroslag pressure welding, should be carried out in accordance with the choice of welding parameter test welding and specimen test, in order to determine the reasonable welding parameters. Qualified before formal production. When using semi-automatic welding equipment, automatic control, should according to determine the parameters of the equipment of various control data set, in order to ensure weld quality is reliable.
3.8 the welding operation point.
3.8.1 closed loop, arc: through the lever or the switch on the control box, through to the current welding machine circuit and the power of input circuit, between reinforced end arc ignition, start welding.
3.8.2 arc process: after arc ignition, should be controlled voltage value. Borrow rib joystick kept certain spacing between reinforced face up and down, arc process time delay, the flux are melting and the formation of the necessary depth of slag pool.
3.8.3 electroslag process: then gradually under the steel bar, steel bar end is inserted in the history of the slag pool, arc extinguishing, in the process of electroslag latency, make whole section steel melts faster.
3.8.4 extrusion power: electroslag process ended, and quickly to steel bar, the bar face under transverse and touch each other, strike out of slag and molten metal. At the same time to cut off the welding power source.
3.8.5 welding joint, should rest after 20 ~ 30 s (welds in cold area, the rest time should be appropriately extended), recycled flux and unload welding jig.
3.9 quality check: in the steel bar electroslag pressure welding in the welding production, welding shall be carried out seriously self-checking, if discover the eccentric, bending, welding defects such as burns, welding is not full, should remove heavy welding joint, and find the reason, eliminate in a timely manner. Removal of joint, reinforcement of heat affected zone, namely the weld center about 1.1 times the length of the steel bar diameter within the scope of the part should be removed.
4 quality standards
4.1 ensure project;
4.4.1 quality and varieties of steel, must comply with the design requirements and the provisions of the relevant standards.
Note: imported steel should first through chemical composition test and welding test, accord with the relevant provisions of the rear can welding.
Inspection method: inspect the factory quality certificate and test report.
4.1.2 of the specifications of the steel bar, the position of the welding joint, the same section with joint reinforced area percentage, must comply with the design requirements and norms.
Methods: to observe the or feet quantity check.
4.1.3 electroslag pressure welding head mechanical performance testing must be qualified.
From each batch of joint mechanical properties test, taking three random joint in tensile test.
4.1.3.1 in general structure, level with 300 steel joint as a batch.
4.1.3.2 in cast-in-place reinforced concrete multilayer structure, with each floor or construction section of the level of steel joint as a group, are still less than 300 joint as a batch.
Inspection method: inspect welding specimens in the test report.
4.2 basic items: reinforcing steel bar electroslag pressure welding head should carry on appearance inspection, the results shall meet the following requirements:
2 welding package is relatively uniform, highlights at least above 4 mm steel surface.
4.2.2 electrodes in contact with the steel bar, no obvious burn defect.
Holdings of joint bending Angle is not greater than 4 °.
4.2.4 the joint axis deviation should be less than 0. L steel bar diameter, at the same time is not more than 2 mm.
Appearance inspection unqualified should remove heavy welding joint, or to take remedial measures.
Test method: visual or measurement.
5 finished product protection
Welding joint, should stop to unload fixture after 20 ~ 30 s, in order to avoid bending joint.
6 should pay attention to quality problems
6.1 in the steel bar electroslag pressure welding production, should pay attention to any link of the whole welding process. Joint parts should be clean; Reinforced installation should be solidarity; Fixture fastening, fight shake; Arc ignition process, and strive to reliable; Arc process, time delay, electroslag process, short and stable; Extrusion process, the pressure properly. If the abnormal phenomenon. Should consult table 4 to 24 search reason, keep clear of in time.
6.2 electroslag pressure welding in minus temperature conditions, but when the environment temperature is below - 20 ℃, is unfavorable for welding.
Rain and snow is unfavorable for welding, welding must be applied when the cover of the effective measures should be taken. Not cooling after welding joint, should avoid touching the ice and snow.
7 quality records
This technology standard should have the following quality records:
7.1 steel factory quality certificate or test report.
7.2 flux qualifier.
7.3 second interview report reinforced mechanical properties.
7.4 imported steel chemical composition inspection report and solderability test report. Domestic reinforced brittle fracture occurred during machining process, welding performance and mechanical performance is obviously not normal, should have a chemical composition inspection report.
7.5 steel joint tensile test report.
Steel bar electroslag pressure welding head welding defects and the prevent measures in table 4 to 24
The items are welding defect prevention measures
1. Straightening steel ends
2. Correct installation jig and reinforced
3. Avoid excessive extrusion
4. Repair or replace the fixture in a timely manner
1. Straightening steel ends
2. Pay attention to the bar on the installation and support
3. Avoid excessive discharge after welding fixture
4. Repair or replace the fixture
3
Welding thin and big package 1. Reduce spinning speed
2. Decrease the welding current
3. To reduce welding time
1. Reduce the welding current
2. The welding time
3. Pay attention to the starting point of the jaw, to ensure that the steel bar extrusion in place
5
Not solder
1. Increase the welding current
2. Avoid welding time is too short
3. The inspection jig, ensure reinforcement under freely
6
Welding package uneven
1. The steel bar end to level off
2. The loading flux uniform as far as possible
3. To extend the time of welding, appropriate increase the fusion quality
7
Gas hole
1. According to the specified requirements for flux
2. Remove steel welding parts of the rust
3. Ensure the embedment depth by welding in flux
1. Reinforced conductive parts remove all rust
2. The clamping bar as far as possible
1. To seal leakage flux tank hole
2. Avoid too fast recovery after welding flux
1 scope
The technology standard is applicable to industrial and civil construction in the cast-in-place reinforced concrete structure Ⅰ 14 ~ 40 mm in diameter to Ⅱ vertical or diagonal (tilt 4:1) reinforcing bar connection.
2 construction preparation
2.1 material and main equipments:
2.1.1 reinforced: reinforced level, diameter must comply with the design requirements, have the factory certificate and retest report. Imported steel shall also have the chemical second-round exam list, its chemical composition should meet the requirements of welding, and shall have the solderability test.
2.1.2 flux.
2.2.2.1 flux performance shall comply with the terms of GB5293 carbon steel submerged arc welding with flux. Flux models for HJ401, commonly used for smelting high manganese manganese in high silicon low fluoride flux or high silicon low fluoride flux.
2.1.2.2 flux should be stored in dry warehouse, prevent to be affected with damp be affected with damp. If be affected with damp be affected with damp, before use must be approved by 250 ~ 300 ℃ for 2 h.
2.1.2.3 use recycling flux, should remove slag and sundry, and should be evenly mixed with the new flux used.
2.1.2.4 flux should be the factory certificate.
2.1.3 main machines:
2.1.3.1 manual electroslag pressure welding equipment including: welding power source, control box, the welding jig, flux tank, etc.
2.1.3.2 automatic electroslag pressure welding equipment (preferred) including: welding power source, control box, box operation, welding head, etc.
2.1.3.3 welding power source. Steel bar electroslag pressure welding appropriate USES secondary high no-load voltage (TSV) of ac or dc welding power source. (32 mm diameter and the following general steel welding, the welding power supply capacity of 600 a can be used; more than 32 mm diameter and steel welding, the welding power supply capacity should be adopted for 1000 a). When the welding machine capacity is small, also can use smaller capacity of the same model, with the performance of the two parallel machine.
2.2.1 welder must hold a valid welder examination certificate.
2.2.2 equipment should comply with the requirements. Welding jig should have enough stiffness, under the maximum allowable load should be mobile and flexible, easy to operate. The diameter of the solder pot, ADAPTS to the rebar diameter welding does not burn out in the welding process. Voltmeter, time display should be equipped so that the operator grasp accurately the welding parameters.
Then the power should comply with the requirements. When the power supply voltage drop is greater than 5%, it is unfavorable to welding.
2.2.4 job site shall have security protection measures, formulate and implement the safety technical measures, strengthen labor protection welders, prevent burns, electric shock, fire, explosion and burning machine.
2.2.5 note joint position, pay attention to the same extent in joint reinforced area percentage, does not conform to the concrete structure engineering construction and acceptance standard "regulations on terms, to adjust the joint position before welding.
3 operation process
3.1 process:
Check equipment, power supply - reinforced end preparation - choose to installation of welding jig and reinforced, welding parameters
Welds - recycling flux to unload jig, quality inspection
3.1.1 electroslag pressure welding process:
Closed circuit to arc, arc power to electroslag process, extrusion process
3.2 check equipment, power supply, ensure the normal state of the at any time, it is strictly prohibited to overload.
3.3 bar end preparation:
Prior to installation, welding parts and steel electrode jaw contact (150) mm segment of steel on the surface of a rusty spot, oil pollution, sundry goods and so on, should be clean, reinforced side if there is bent, and twisted, must be paid to the straightening or resection, but shall not use the hammer straightening.
3.4 choose welding parameters:
Steel bar electroslag pressure welding welding parameters mainly include: welding current, welding voltage and welding current time, see table 4-23.
Different diameter steel welding, according to the small diameter steel bar to select parameters, welding current extended by about 10%.
3.5 installation of welding jig and reinforced: fixture clamping jaw under next reinforced end position, generally for 1/2 flux tank height below 5 ~ 10 mm, to ensure that the soldering flux has enough YanMai depth.
After reinforcement into the fixture on the jaw, alignment, the starting point of the moving clamp, the fluctuation of steel welding parts in coaxial state,
Steel welding welding voltage (V) welding current time (s)
The diameter of
(mm) current
(A) arc process
U2-1 electroslag process
U2-2 arc process
T1 electroslag process
t2
16, 200 ~ 200 40 ~ 45 22 ~ 27 14 April
18 250 ~ 250 40 ~ 45 22 ~ 27 15 May
20, 300 ~ 300 40 ~ 45 22 ~ 27 17 May
22 350 ~ 350 40 ~ 45 22 ~ 27 June 18
25, 400 ~ 450 40 ~ 45 22 ~ 27 June 21
28 500 ~ 550 40 ~ 45 22 ~ 24 June 27
32, 600 ~ 650 40 ~ 45 22 ~ 27 July 27
36, 700 ~ 750 40 ~ 45 22 ~ 27 thirty eight
40, 850 ~ 850 40 ~ 45 22 ~ 27 to 33
Before clamping bar.
Reinforced once clamping, beware of shaking, in order to avoid deformation of reinforced dislocation and fixture.
3.6 arc was laid with wire ball (also). Fill in solder flux tank, was laid.
3.7 test weld, as a specimen, determine welding parameters: before the formal for steel bar electroslag pressure welding, should be carried out in accordance with the choice of welding parameter test welding and specimen test, in order to determine the reasonable welding parameters. Qualified before formal production. When using semi-automatic welding equipment, automatic control, should according to determine the parameters of the equipment of various control data set, in order to ensure weld quality is reliable.
3.8 the welding operation point.
3.8.1 closed loop, arc: through the lever or the switch on the control box, through to the current welding machine circuit and the power of input circuit, between reinforced end arc ignition, start welding.
3.8.2 arc process: after arc ignition, should be controlled voltage value. Borrow rib joystick kept certain spacing between reinforced face up and down, arc process time delay, the flux are melting and the formation of the necessary depth of slag pool.
3.8.3 electroslag process: then gradually under the steel bar, steel bar end is inserted in the history of the slag pool, arc extinguishing, in the process of electroslag latency, make whole section steel melts faster.
3.8.4 extrusion power: electroslag process ended, and quickly to steel bar, the bar face under transverse and touch each other, strike out of slag and molten metal. At the same time to cut off the welding power source.
3.8.5 welding joint, should rest after 20 ~ 30 s (welds in cold area, the rest time should be appropriately extended), recycled flux and unload welding jig.
3.9 quality check: in the steel bar electroslag pressure welding in the welding production, welding shall be carried out seriously self-checking, if discover the eccentric, bending, welding defects such as burns, welding is not full, should remove heavy welding joint, and find the reason, eliminate in a timely manner. Removal of joint, reinforcement of heat affected zone, namely the weld center about 1.1 times the length of the steel bar diameter within the scope of the part should be removed.
4 quality standards
4.1 ensure project;
4.4.1 quality and varieties of steel, must comply with the design requirements and the provisions of the relevant standards.
Note: imported steel should first through chemical composition test and welding test, accord with the relevant provisions of the rear can welding.
Inspection method: inspect the factory quality certificate and test report.
4.1.2 of the specifications of the steel bar, the position of the welding joint, the same section with joint reinforced area percentage, must comply with the design requirements and norms.
Methods: to observe the or feet quantity check.
4.1.3 electroslag pressure welding head mechanical performance testing must be qualified.
From each batch of joint mechanical properties test, taking three random joint in tensile test.
4.1.3.1 in general structure, level with 300 steel joint as a batch.
4.1.3.2 in cast-in-place reinforced concrete multilayer structure, with each floor or construction section of the level of steel joint as a group, are still less than 300 joint as a batch.
Inspection method: inspect welding specimens in the test report.
4.2 basic items: reinforcing steel bar electroslag pressure welding head should carry on appearance inspection, the results shall meet the following requirements:
2 welding package is relatively uniform, highlights at least above 4 mm steel surface.
4.2.2 electrodes in contact with the steel bar, no obvious burn defect.
Holdings of joint bending Angle is not greater than 4 °.
4.2.4 the joint axis deviation should be less than 0. L steel bar diameter, at the same time is not more than 2 mm.
Appearance inspection unqualified should remove heavy welding joint, or to take remedial measures.
Test method: visual or measurement.
5 finished product protection
Welding joint, should stop to unload fixture after 20 ~ 30 s, in order to avoid bending joint.
6 should pay attention to quality problems
6.1 in the steel bar electroslag pressure welding production, should pay attention to any link of the whole welding process. Joint parts should be clean; Reinforced installation should be solidarity; Fixture fastening, fight shake; Arc ignition process, and strive to reliable; Arc process, time delay, electroslag process, short and stable; Extrusion process, the pressure properly. If the abnormal phenomenon. Should consult table 4 to 24 search reason, keep clear of in time.
6.2 electroslag pressure welding in minus temperature conditions, but when the environment temperature is below - 20 ℃, is unfavorable for welding.
Rain and snow is unfavorable for welding, welding must be applied when the cover of the effective measures should be taken. Not cooling after welding joint, should avoid touching the ice and snow.
7 quality records
This technology standard should have the following quality records:
7.1 steel factory quality certificate or test report.
7.2 flux qualifier.
7.3 second interview report reinforced mechanical properties.
7.4 imported steel chemical composition inspection report and solderability test report. Domestic reinforced brittle fracture occurred during machining process, welding performance and mechanical performance is obviously not normal, should have a chemical composition inspection report.
7.5 steel joint tensile test report.
The items are welding defect prevention measures
1. Straightening steel ends
2. Correct installation jig and reinforced
3. Avoid excessive extrusion
4. Repair or replace the fixture in a timely manner
1. Straightening steel ends
2. Pay attention to the bar on the installation and support
3. Avoid excessive discharge after welding fixture
4. Repair or replace the fixture
3
Welding thin and big package 1. Reduce spinning speed
2. Decrease the welding current
3. To reduce welding time
1. Reduce the welding current
2. The welding time
3. Pay attention to the starting point of the jaw, to ensure that the steel bar extrusion in place
5
Not solder
1. Increase the welding current
2. Avoid welding time is too short
3. The inspection jig, ensure reinforcement under freely
6
Welding package uneven
1. The steel bar end to level off
2. The loading flux uniform as far as possible
3. To extend the time of welding, appropriate increase the fusion quality
7
Gas hole
1. According to the specified requirements for flux
2. Remove steel welding parts of the rust
3. Ensure the embedment depth by welding in flux
1. Reinforced conductive parts remove all rust
2. The clamping bar as far as possible
1. To seal leakage flux tank hole
2. Avoid too fast recovery after welding flux
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