JB/T 8423-1996 Method for evaluating welding process performance of welding electrodes
Some standard content:
JB/T 8423—96
This standard mainly refers to the methods used in the national welding rod quality evaluation organized by the Ministry of Machinery Industry in 1979, 1984 and 1989, and at the same time improves the shortcomings of the evaluation methods for some items. This standard shall be implemented from July 1, 1997. This standard is proposed and managed by the National Welding Standardization Technical Committee. The drafting unit of this standard: Harbin Welding Research Institute of the Ministry of Machinery Industry. The main drafters of this standard: Li Chunfan and Chen Mo. 1398
1 Scope
Machinery Industry Standard of the People's Republic of China
Evaluation Method of Welding Process Performance of Electric Welding Rods
JB/T8423—96
This standard specifies the evaluation method of welding process performance of $3.2～$5.0mm electric welding rods. Other specifications of welding rods can also refer to this standard.
This standard applies to carbon steel electrodes, low alloy steel electrodes, stainless steel electrodes, cladding electrodes, cast iron electrodes, nickel and nickel alloy electrodes, aluminum and aluminum alloy electrodes, copper and copper alloy electrodes and other electrodes for manual arc welding. This standard is only used as an evaluation method for the research and assessment of welding process performance of welding electrodes in the welding electrode industry. 2 Assessment Items
2.1 Arc Stabilitybzxz.net
2.2 Welding Slag Removability
2.3 Re-striking Performance
2.4 Welding Spatter Rate
2.5 Melting Coefficient
2.6 Electrode Deposition Efficiency
2.7 Welding Dust Generation
2.8 Electrode Power Consumption
3 Assessment Methods
If there is no special requirement in the assessment, the electrode drying specification and welding current shall be in accordance with the provisions of the "Welding Material Product Sample" compiled by the Ministry of Machinery Industry. The welding current for flat welding shall be 15A lower than the maximum current specified in the sample. AC and DC dual-purpose electrodes shall be used for AC welding. Except for the corresponding test plates for inlay, copper and aluminum electrodes, other electrodes shall use Q235, 16Mn or corresponding steel plates. The welding surface of the test plate shall be free of oxide scale, oil stains, etc.
Arc extinguishing and breathing times, melting coefficient, welding rod deposition efficiency, power consumption and other items can also be measured by corresponding instruments. 3.1 Arc stability
Arc stability assessment includes two indicators: arc breaking length and arc extinguishing and breathing times. 3.1.1 Arc breaking length
3.1.1.1 Clamp the welding rod vertically on the bracket, and the arc end of the welding rod is 2.5mm away from the test plate. 3.1.1.2 The size of the test plate is 200mm×200mm×(12~20）mm. 3.1.1.3 Start the welding machine, ignite the arc with a graphite sheet, and the welding rod burns automatically until the arc is broken. 3.1.1.4 After the arc is broken, gently knock off the slag on the weld, and remove the slag and coating at the end of the welding rod. 3.1.1.5 Measure the distance between the end of the welding rod and the weld vertically, which is the arc breaking length of the welding rod (mm). 3.1.1.6 Three electrodes of each type of welding rod shall be measured and the arithmetic mean shall be taken. 3.1.2 Arc extinguishing and breathing times
3.1.2.1 The test shall be conducted on a welding machine with a low no-load voltage. Approved by the Ministry of Machinery Industry of the People's Republic of China on September 3, 1996 and implemented on July 1, 1997
JB/T8423-96
3.1.2.2 The size of the test plate is 400mm×100mm×(12~20)mm. 3.1.2.3 One weld pass shall be welded on the test plate, and the remaining length of the welding rod shall be 50mm. 3.1.2.4 During welding, observe the arc extinguishing and breathing times. Three electrodes of each type of welding rod shall be measured and the arithmetic mean shall be taken. 3.2 Welding slag removal
3.2.1 Test Welding is performed on two test plates of 400mm×100mm×(14~16)mm in the butt groove. The test plates are fixed before welding. The groove angle is 70°±1°. The groove angle of the 5.0mm electrode is 90°±1°. The blunt edge is 1mm. No gap is left. Manual welding is performed. 3.2.2 Single-pass welding is used during welding. The electrode does not swing. The melting ratio of the electrode (melting ratio-bead length/melting electrode length) is about 1:1.3. The remaining electrode length is 50mm.
3.2.3 After the test plate is welded, the weld bead is immediately placed flat on the hammering platform with the weld bead facing downwards to ensure that the ball hammer is at the center of the test plate. A 2kg iron ball is placed on a 1.3m high bracket.
3.2.4 One minute after welding, make the iron ball fall from a fixed point to the center of the test plate in a free fall state with an initial velocity of zero. 3.2.5 The acid electrode is hammered three times in a row, and the alkaline electrode is hammered five times in a row. 3.2.6 Each electrode is measured twice and the arithmetic mean is taken. 3.2.7 Slag removal rate calculation formula
Slag removal rate = Total length of weld bead (mm) = Total length of weld bead (mm) × 100% Total length of weld bead (mm)
Total length of unslag removal = Length of unslag removal + Length of severe slag + 0.2 (length of "slightly slag") 3.3 Re-induction performance
3.3.1 The size of the test plate is 400 mmX×100mmX(12～20)mm (welding plate) and 200 mm×100mm×(1220)mm (re-striking plate), the re-striking plate must be free of oxide scale and smooth and in good contact with the wire. 3.3.2 The arc is stopped when the welding rod is on the welding plate for 15s. After the arc is stopped for the specified "interval" time, the arc is re-strike on the re-striking plate. 3.3.3 When re-striking, the melting end of the welding rod is in vertical contact with the steel plate. No knocking action is performed and the welding rod sleeve must not be damaged. 3.3.4 The same "interval" time is repeated three times with the same welding rod, and welding must be performed for 15s each time before re-striking. If "arc flash or short circuit state" appears more than two times in the three times, it is judged as passed, and another welding rod is replaced for the next "interval" time assessment. 3.3.5 The "interval" time for acidic electrodes starts from 5s, and that for alkaline electrodes starts from 1s. 3.4 Welding spatter rate
3.4.1 The test plate size is 280mm×50mm×20mm. 3.4.2 The test plate is placed vertically on a copper plate about 3mm thick. 3.4.3. On the copper plate, a 400mm high elliptical cylinder surrounded by a copper sheet about 1mm thick is placed, and its circumference is 1500~2000mm to prevent the spatter from being lost.
3.4.4 The test is carried out in the elliptical cylinder, and the welding rod melts until the arc is extinguished about 50mm away from the clamping end. 3.4.5 Three welding rods are taken for each test and welded on three test plates respectively. 3.4.6 The weight of the welding rod is weighed before welding, and the weight of the welding rod head and spatter (slag and iron beads) is weighed after welding. The weighing accuracy is 0.01g. The spatter on the surface of the test plate is not counted.
3.4.7 Calculation formula
Spatter weight (g)
Spatter rate Amount of a sample (thin fruit weight (@×100%3.5 Melting coefficient
3.5.1 The size of the test plate is 280mm×50mm×20mm. 3.5.2 Three electrodes are taken for each test and welded on three test plates respectively. The remaining length of the electrode is about 50mm. 1) No slag removal - the slag is completely not removed and is in the original state after welding. 2) Severe slag sticking - the slag surface falls off, there is still a thin slag layer, and the weld metal surface is not exposed. 3) Slightly slag sticking - there is slag sticking on the side of the weld, and the weld metal is partially exposed or the slag surface falls off, and the weld metal leaks are exposed. 2400
3.5.3 Measure the length of the electrode before welding.
JB/T 8423—96
During welding, the welding current and welding time must be accurately recorded. 3.5.5 After welding, remove the coating of the remaining welding rod, polish it with fine sandpaper, measure the length of the welding core after welding and weigh it, with a weighing accuracy of 0.1g. 3.5.6 Calculation formula
3.6 Welding rod deposition efficiency
Melting coefficient [g/(A·h)) = Welding core weight before welding (s) = Welding core weight after welding (g) Welding current (A) × welding time (h)
Welding core weight before welding (g) = Welding rod length (mm) × Welding core weight after welding (g) Welding core length after welding (mm)
The test plate size is 280mm×50mm×20mm. 3.6.1
Take three welding rods for each group of tests and weld them on three test plates respectively. The remaining length of the welding rod is about 50 mm. 3.6.2
3.6.3 Measure the length of the welding rod and weigh the weight of the test plate before welding, and weigh the weight of the test plate again after welding, with a weighing accuracy of 0.1g. 3.6.4 Remove the coating of the remaining welding rod, polish it with fine sandpaper, measure the length of the welding core after welding and weigh it, with a weighing accuracy of 0.1g. 3.6.5 Calculation formula
Weight of deposited metal of three welding rods (piece) × 100% welding rod deposition efficiency
Total weight of three molten welding cores (g)
Weight of molten metal (g) = Weight of test plate after welding (g) - Weight of test plate before welding (g) Total weight of molten welding core (g) = Length of welding rod (ml) ※Weight of welding core after welding (2) Total weight of welding core after welding (g) Length of welding core after welding (mm)
3.7 Welding dust generation
3.7.1 The dust generation of welding rods is determined by the exhaust collection method. The test device is a semi-sealed container with a volume of about 0.12m (diameter 500mm, height 600mm), dust measuring device see Figure 1. o
1-cooling water; 2-test plate, 3-U-type water pressure gauge, 4-observation hole, 5-simplified body; 6-large body; 7-filter paper and steel mesh; 8-small cone; 9-hose; 10-LZB-25 rotor flowmeter; 11-two-way piston: 12 vacuum pump Figure 1 Composition of dust measuring device
3.7.2 The size of the test plate is 300mm×200mm×(12~20)mm. 3.7.3 Three welding rods are used for each test, numbered and weighed separately, with a weighing accuracy of 0.1g. 3.7.4 Three numbered slow quantitative filter papers and a paper bag containing about 5g of absorbent cotton are placed in the dried blood at the same time and dried for more than 2h, and then quickly weighed with a 1/10000 analytical balance. 3.7.5 Before the test, clean the cylinder and the inner wall of the large and small cones of the dust measuring device, and then blow dry with a hair dryer. 3.7.6 Place the test plate and welding rod in the cylinder, then place a weighed filter paper under the pot net at the opening of the small cone and tighten the large and small cones. Connect the cooling water, start the mechanical pump, open the two-way piston, adjust the air extraction volume to 5m/h, observe whether the water pressure difference of the U-type water pressure gauge is normal, and the cylinder should be negative pressure, and then weld. 401
JB/T8423—96
3.7.7 During welding, the welding rod should be as vertical as possible without swinging, the weld spacing is about 10mm, and the remaining length of the welding rod is about 50mm. 3.7.8 After stopping welding, continue to evacuate for 5min, close the two-way piston, open the small cone, remove the dust collection filter paper, fold it, and store it separately in a small paper bag. Use a small amount of weighed absorbent cotton to wipe the dust on the inner wall of the small cone, and put the dusty cotton back to its original place. 3.7.9 Repeat the above operation. After welding three wires, open the caps of the large and small cones. Use the remaining absorbent cotton to wipe the dust on the large cylinder and the inner wall of the large and small cones. Put the dusty cotton back to its original place. In order to avoid mixing with splashing particles, the area below 180mm below the lower part of the large cylinder is not covered. 3.7.10 Put the dusty absorbent cotton and filter paper into the drying blood together. The drying time is the same as the drying time before weighing the original weight. Then weigh it for the second time and weigh the weight of each welding rod head separately. 3.7.11 Calculation formula
(Agi+4g:)/3×1 000
Dust generation (g/kg) =
Ag1=weight of filter paper after dust collection (g)-weight of filter paper (g) Ag2=weight of cotton after dust collection (g) weight of cotton (g) Aga-weight of welding rod (g) weight of welding rod head (g) The above calculation formula is the dust generation per kg of each welding rod, and the dust generation of welding rod is the arithmetic average of three welding rods. 3.8 Power consumption of welding rod
3.8.1 The size of the test plate is 280mm×50mm×20mm. 3.8.2 Three welding rods are taken for each test and welded on three test plates respectively. The remaining length of the welding rod is about 50mm. 3.8.3 The weight of the test plate is weighed before and after welding. The weighing accuracy is ±1g, and the weight increase is the weight of the molten metal. 3.8.4 During welding, accurately record the welding current (A), welding voltage (V) and welding time (h). 3.8.5 Calculation formula
Power consumption of three welding rods (100)
Power consumption (kWh/kg) = weight of deposited metal of three welding rods 0() × 1 0004 Assessment record
When conducting the above process assessment, the following contents should be accurately recorded: - welding rod model, brand, specification and drying conditions; welding power source model, polarity, no-load voltage, welding current; - test plate size, material and test plate treatment. 402
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