Ferritic steel barrel butt-junction circular-seam hot-wire TIG multi-layer multipath welding method

A low-alloy steel, multi-layer and multi-channel technology, applied in welding equipment, heat treatment furnace, arc welding equipment, etc., can solve the problems of low deposition efficiency and long processing cycle, so as to improve processing quality, reduce processing cost, prevent The effect of slag accumulation

Inactive Publication Date: 2009-03-25

HARBIN JIANCHENG GRP

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AI-Extracted Technical Summary

Problems solved by technology

[0003] The object of the present invention is to provide a low-alloy steel cylinder butt ring seam hot wire TIG multi-layer multi-pass welding method, which solves the problem ...

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Abstract

Disclosed is a hot filament TIG multi-layer and multi-track welding method for low alloy steel cylinder butt joint girth welding, relating to a low alloy steel cylinder butt joint girth welding method which solves the problems in the prior low alloy steel cylinder butt joint girth welding that the welding deposition rate of the cold filament TIG filling welding is low so as to result in low product qualification ratio and the long process cucle. The welding process includes: firstly, processing the slope mouth of the end face the awaiting welding cylinder piece; secondly, processing the welding for the U-shape slope mouth, pre-welding and preheating for the two awaiting welding cylinder pieces, performing bottom welding, multi-layer and multi-track filling welding and multi-layer and multi-track cap welding; thirdly, post-heating and degassing hydrogen; fourthly, stress removing and annealing; fifthly, modifying and quenching. The cylinder butt joint welding by the invention can increase the welding deposition ratio of the welding filament by 2 to 3 times and greatly increase the product qualification ratio by first delivery check. The method of the invention is particularly applicable to the 35CrMnSiA alloy cylinder butt joint welding.

Application Domain

Arc welding apparatusFurnace types +1

Technology Topic

Alloy steelHot filament +4

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Examples

Experimental program(2)

Example Embodiment

[0025] Specific implementation manner 1: The specific process of the low-alloy steel cylinder butt joint circumferential seam hot wire TIG multi-layer multi-pass welding method described in this embodiment is:

[0026] Step 1: Machining the grooves on the end faces of the tube to be welded: turning the welding end faces of the two tube parts to be welded into mutually matched blunt U-shaped grooves;

[0027] Step two, welding the U-shaped groove, specifically including the following steps:

[0028] Step 2: Pre-welding and pre-heating the two cylinders to be welded: pre-welding the two cylinders to be welded in place, preheating the furnace, heating temperature 280~300℃, holding time 120± 5 minutes to heat the product evenly;

[0029] Step two, take the test piece processed in step two out of the furnace, put it into the fixing device of the automatic welding machine, adjust the relative position of the welding gun, welding wire 1, and work piece 5. The distance between the end of the welding wire 1 and the tungsten electrode 4 is 3.5mm~5mm, the advance L of the welding gun is 15mm~25mm, and the wire feeding angle B of the hot wire gun 2 is 35°~50°;

[0030] Step two and three, bottom welding, using single-sided welding and double-sided forming technology for bottom welding;

[0031] Step two and four. Multi-layer and multi-pass fill welding: single-layer double-pass fill welding is used for each layer, the filling thickness is 1/3 of the entire weld, and the width of each weld bead superimposed on the previous weld bead is 1 /2 to 1/3 of the weld bead width. When each layer of welding is completed, that is, when one circle of welding is completed, stop the wire feed, adjust the welding torch to the next position to be welded, and use the arc to melt the edge of the previous bead. Wire feeding starts welding, and hot wire welding is used from the third layer;

[0032] Step two and five. Multi-layer and multi-pass cover welding: hot wire welding is used, and the weld deposit is 2/3;

[0033] Step 3. Post-heating hydrogen removal: Put the welded test piece into the furnace immediately and heat it at a holding temperature of 280℃~300℃, holding time of 120±5 minutes, and then air cooling to room temperature after being discharged from the furnace;

[0034] Step 4. Stress-relieving annealing: Put the test piece after hydrogen removal into the furnace, the temperature of entering the furnace is ≤300℃, the holding temperature is 580±10℃, the holding time is 120±5 minutes, and it is cooled to ≤300℃ with the furnace, and then out of the furnace Air cooling to room temperature;

[0035] Step five, quenching and tempering treatment: furnace entering temperature ≤500℃, preheating temperature 680℃, holding time 180±5 minutes, heating temperature 900±10℃, holding time 90±5 minutes, using oil as quenching medium for quenching Time 18-20 minutes; tempering, holding temperature 230±10℃, holding time 180±5 minutes, using water as cooling medium, cooling time 15-18 minutes.

[0036] The blunt-edged U-shaped bevel described in step 1 of this embodiment can adopt a socket-fitted blunt edge, see figure 1 As shown, the thickness P of the blunt edge is 1.5mm~3.5mm, the angle A of the groove surface is 20°~30°, and the chamfer radius R of the bottom of the groove is 6mm~8mm. The use of this blunt U-shaped groove has good self-alignment.

[0037] In step 2, the positional relationship of the welding gun, welding wire 1, tungsten electrode 4 and workpiece 5 is shown in figure 2 Shown.

[0038] In steps two and three, the welding wire diameter is Φ1.2mm, the welding current is 145A~160A, the arc length is 3mm~4mm, the corresponding voltage is 12V~14V, and the workpiece speed is 120mm/min.

[0039] In the multi-layer and multi-pass fill welding of step two and four, and the multi-layer and multi-pass cover welding of step two and five, the specific number of layers to be welded in each step is determined according to the wall thickness of the tube to be welded.

[0040] In step two and five, a welding wire with a diameter of Φ1.6mm is used for cover welding.

[0041] In step two and five, under the premise of a certain welding speed, the heat input and welding speed increase layer by layer. Specifically, it can be realized by increasing the parameters such as welding current, welding voltage, hot wire current, wire feeding speed, etc. layer by layer.

[0042] After using the method described in this embodiment to perform butt welding on the 35CrMnSiA tube, the test results are:

[0043] Then the post-weld heat-treated 35CrMnSiA specimen was subjected to tensile test in accordance with GB2651 "Tensile Test Method for Welded Joints". The specimen was processed into a circular specimen. The size of the test section: φ10×60mm, the size of the chuck φ20×50, tensile The test result is: the tensile strength is 1800~1900Mpa (qualified index: the product specification is not less than 1620Mpa).

[0044]The 35CrMnSiA specimen with post-weld heat treatment was subjected to impact test in accordance with GB2650 "Impact Test Method for Welded Joints". The size of the specimen is 10×10×55mm, the notch type is U notch, and the notch position is perpendicular to the weld. Impact test result: joint impact Absorbed work is 40~45J (qualified index: product specification is not less than 36J). Rockwell hardness: HRC50~55 (Qualified index: product specification HRC45~55J).

[0045] The appearance of the weld is beautiful, and the welding wave is uniform. There are no cracks, pores, undercuts, incomplete penetration and other welding defects in the weld and heat-affected zone. The weld is subjected to 100% X-ray inspection. The quality of the weld is assessed according to JB47302.2- The 2005 "Non-destructive Testing of Pressure Equipment" standard stipulates that the weld quality is Class I.

[0046] The above test results show that the low-alloy steel cylinder body butt joint circumferential seam hot wire TIG multi-layer and multi-pass welding method for pipe fittings butt welding can improve the welding quality of products and solve the problem of processing and manufacturing by outsourcing manufacturers. The problems of long cycle and high production cost also solve the problem of low deposition efficiency of cold-wire TIG filler welding. The deposition speed of hot-wire TIG welding wire can be increased by 2 to 3 times, which reduces labor intensity. Hot-wire TIG welding technology It is the development trend of TIG thick wall fill welding.

Example Embodiment

[0047] Specific embodiment 2: The difference between this embodiment and the specific embodiment is that the low-alloy steel cylinder butt joint circumferential seam hot wire TIG multilayer multi-pass welding method is different in that the wall thickness S of the cylinder to be welded is 15mm~ 50mm, the difference of the welding method is:

[0048] In the bottom welding process of steps two and three, a welding wire with a diameter of 1.2mm is used, the welding current is 145A~160A, the arc length is 3mm~4mm, the corresponding voltage is 12V~14V, and the rotation speed is 120mm/min. The diameter is 4mm~5mm, the end angle of the tungsten electrode is 30°~40°, the length of the tungsten electrode protruding from the protection nozzle 3 is 6mm~8mm, the inner diameter of the protection nozzle 3 is 11mm, and the gas flow rate is 18L/min~22L/min, welding gun advance is 25mm~30mm,

[0049] The program parameter setting of TIG welding is shown in Table 1:

[0050] Table 1

[0051]

[0052] In this embodiment, the welded inner and outer welds are beautifully formed, the welds have uniform and regular waves, the blunt-edge socket assembly line has been completely fused, the back bead weld is 1mm to 1.5mm high and the weld width is 5mm-6mm.

[0053] After the bottom welding is completed, directly switch to filling welding without arc extinguishing. In step two and four, six layers of multi-layer and multi-pass fill welding are performed. The welding parameters of each layer are shown in Table 2.

[0054] Table 2

[0055] Number of weld bead layers Wire feeding speed (mm/min) Welding current (A) Hot wire current (A) level one 800 180

[0056] Number of weld bead layers Wire feeding speed (mm/min) Welding current (A) Hot wire current (A) Second floor 1000 200 - the third floor 1200 220 30 Fourth floor 1400 240 40 Fifth floor 1600 260 50 Sixth floor 1800 260 60

[0057] In the welding process, the first and second layers do not use hot wire current, which can effectively prevent the back bead from being too collapsed.

[0058] In the above process, when using hot wire welding, adjust the hot wire current under the premise that the wire feeding speed is determined, and the generated resistance heat causes the end of the welding wire to be in contact with the molten pool to be heated and change color and bluish. The hot wire current is matched with other welding parameters, and the weld shape is the best.

[0059] During hot wire welding, the hot wire current should not be too large. If it is too large, it will cause the rust-proof copper plating layer of the welding wire to be heated and evaporate, the welding wire is excessively oxidized, and the ends are blacked, resulting in excessive weld pool slag and poor weld formation. , The probability of weld defects increases.

[0060] In the multi-layer and multi-pass cover welding process of step two and five, five-layer welding is performed. The specific welding process is that as the welding height increases, the welding parameters of each layer are different. For specific parameters, see Table 3:

[0061] table 3

[0062] Number of weld bead layers Wire feeding speed (mm/min) Welding current (A) Hot wire current (A) level one 1330～1470 260±8 40±6 Second floor 1710～1890 280±8 50±6 the third floor 2090～2310 300±8 60±6 Fourth floor 2600～2800 320±8 80±6 Fifth floor 3000～3200 330±8 95±6

[0063] In the low-alloy steel cylinder butt joint circumferential seam hot-wire TIG multilayer multi-pass welding method described in specific embodiment one or two, the bottom welding described in step two and three is a key step, and the melting should be observed at any time during the welding process. The molten state of the pool can be controlled in time to control the heat input to ensure the penetration of the molten pool, thereby ensuring that the back of the weld is well formed without collapse and leakage.

[0064] In the process of observing the melting state of the molten pool, you can determine whether the molten pool is penetrated by observing the state of the weld pool and the color of the back weld bead. When the molten pool is penetrated, gravity causes the molten pool to sink and the surface of the molten pool to drop And the area has expanded, the color of the back bead is bright yellow at this time; if the molten pool does not sink, it means that it has not been penetrated, and the color of the back bead is darker to red and yellow; if the molten pool sinks too much, it means The back side collapses to produce weld bumps, and the weld is in danger of burning through. At this time, the color of the back bead is bright yellow. See Table 4 for the relationship between steel color and temperature.

[0065] Table 4

[0066] colour Dark maroon Maroon Dark cherry red Deep cherry red Cherry red Light cherry red Temperature(℃) 550-580 580-650 650-730 730-770 770-800 800-830 colour Bright cherry red Orange Dark orange Bright orange White orange Temperature(℃) 830-960 960-1050 1050-1150 1150-1250 1250-1300

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PUM

Property	Measurement	Unit
Diameter	1.6	mm
Tensile strength	1800.0 ~ 1900.0	mPa
Wall thickness	15.0 ~ 50.0	mm
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Prevent slag buildup
Improve processing efficiency

Method for preventing slag from being accumulated at center of high-chromium vanadium-bearing titanomagnetite hearth

InactiveCN107419046AImproved thermal stabilityPrevent slag buildupBlast furnace detailsSlagChromium

Owner:PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP

Ferritic steel barrel butt-junction circular-seam hot-wire TIG multi-layer multipath welding method

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Examples

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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