Large heat input thick plate welding method meeting welding coarse grain area CTOD inspection

Abstract

The invention discloses a large linear energy thick plate welding method meeting the requirement for CTOD inspection of a welding coarse grain area, which combines the characteristic of small range of large linear energy welding equipment and a welding heat affected zone grain coarse area (GCHAZ), and specially formulates an I-type welding groove and a single-pass welding process in order to ensure the accuracy of GCHAZ toughness value evaluation. The distribution state of cladding metal in the groove is controlled by adjusting voltage, current, the position of a welding gun, the angle of the welding gun, dry elongation, the swing amplitude and the swing speed, it is guaranteed that heat and the cladding metal amount of any longitudinal position in the groove are the same, welding seam metal and a fusion line (GCHAZ) are perpendicularly distributed with a rolling face, and finally precrack notches in the CTOD test are formed in the GCHAZ as many as possible.

Description

Technical Field

[0001] The invention belongs to the field of welding technology, and specifically relates to a high-energy line thick plate welding method that meets the CTOD inspection of the welding coarse grain zone, and is mainly aimed at the efficient welding of high-energy line structural thick steel plates with a thickness specification of 20mm to 80mm. Background Art

[0002] The brittle fracture resistance test (CTOD) of GCHAZ welded joints of steel products is an important test item for evaluating the weldability of steel plates, and is often a mandatory test item in pressure vessel welding process assessment, ship plate certification, etc. In recent years, in large-scale construction projects such as shipbuilding, petrochemicals, and LNG storage tanks, more efficient high-energy welding process solutions have been developed and applied one after another compared to traditional welding methods such as manual welding, gas shielded welding, and submerged arc welding. However, the high-efficiency welding operation method brings about a serious decrease in the mechanical properties of GCHAZ in the welding heat affected zone. Therefore, the evaluation of the brittle fracture resistance of GCHAZ welded with high-energy welding is essential.

[0003] The commonly used welding method GCHAZ area CTOD inspection is usually implemented by K-type groove multi-layer multi-pass welding process to ensure that the fusion line is approximately a straight line and perpendicular to the upper and lower surfaces of the steel plate, so that the CTOD test pre-cracks are as much as possible within the GCHAZ, so as to achieve the accuracy of the inspection process. Large wire energy welding (EGW) is a welding process with a forward and backward swing of the welding gun, a V-shaped groove, and a single-pass forming process. The groove can only be symmetrical, and K-type groove welding cannot be achieved. Therefore, obtaining a weld with a fusion line perpendicular to the rolling surface is the key to whether the weld GCHAZ area CTOD inspection can be carried out, and it is also the core of the problem solved by the present invention. Summary of the invention

[0004] The purpose of the present invention is to provide a high-energy-line thick plate welding method that meets the CTOD test of the welding coarse grain zone, that is, a welding process method that meets the high-energy-line welding GCHAZ brittle fracture resistance test (CTOD) to solve the problems in the prior art.

[0005] The present invention is achieved through the following technical solutions: A high-energy thick plate welding method that meets the CTOD inspection of the welding coarse grain zone is characterized by comprising the following steps: 1) Preparation before welding: Remove the surface oil and oxide scale on one side of the groove of the steel plate, select I-type groove with an angle of 0°; use water-cooled copper pads on the back of the specimen and water-cooled copper sliders on the face, and use arc-starting plates of the same material. The length, width and height of the arc-starting plates are: 100*t*(12-18)mm, where t is the plate thickness; 2) Protective gas: 99.99% pure CO2; 3) Gas flow rate: 25L / min~35L / min; 4) Welding process: Leave a gap of 17mm-21mm at the root of the groove. The specific welding parameters are as follows: Current 330A~360A, voltage 33V~36V, welding speed 2.8cm / min~3.2cm / cm, dry extension 30mm-32mm, front stop time 0.8s~1.0s, rear stop time 0.8s~1.0s, swing amplitude 15mm~29mm, swing speed 54mm / s, wire energy 204kj / cm~278kj / cm; 5) Welding process: fix the welding gun position, adjust the welding gun tilt angle 10-11°, the conductive nozzle height is 5-7mm from the upper end of the copper slider air outlet, the longitudinal depth is 10mm~55mm from the surface side, the arc is broken and filled 5mm~8mm, and then continuous arc welding is performed.

[0006] Further: comprising the following steps: 1) Preparation before welding: The groove side of the steel plate is machined to remove surface oil and oxide scale, and an I-type groove is selected with an angle of 0°; a 500*45*25 water-cooled copper liner with a groove width of 18mm~22mm is used on the back of the specimen, and a water-cooled copper slider with a groove width of 20mm~24mm is used on the face, and an arc starter plate of the same material is 100*t*12; 2) Protective gas: 99.99% pure CO2; 3) Gas flow rate: 25L / min~35L / min; 4) Welding process: The groove uses a symmetrical I-type groove, a 17mm gap is left at the root of the groove, and single-wire EGW welding is used; the specific welding parameters are as follows: Current 330A~360A, voltage 33V~36V, welding speed 2.9cm / min~3.2cm / cm, dry extension 30mm, front stop time 0.8s~0.9s, rear stop time 0.8s~0.9s, swing amplitude 15mm~28mm, swing speed 54mm / s, wire energy 204kj / cm~268kj / cm; 5) Welding process: fix the welding gun position, adjust the welding gun tilt angle 10°, the height of the conductive nozzle is 5mm from the upper end of the copper slider outlet, the depth is 1 / 2 of the plate thickness, and the arc is broken and filled 5mm before continuous arc welding.

[0007] Further: comprising the following steps: 1) Preparation before welding: The groove side of the steel plate is machined to remove surface oil and oxide scale, and an I-type groove is selected with an angle of 0°; a 500*45*25 water-cooled copper liner with a groove width of 18mm~22mm is used on the back of the specimen, and a water-cooled copper slider with a groove width of 20mm~24mm is used on the face, and an arc starter plate of the same material is 100*t*18; 2) Protective gas: 99.99% pure CO2; 3) Gas flow: 35L / min; 4) Welding process: The groove uses a symmetrical I-type groove, a 21mm gap is left at the root of the groove, and double-wire EGW welding is used; the specific welding parameters are as follows: Welding gun I: current 350A~360A, voltage 35V~36V, welding speed 2.8cm / min~3.0cm / cm, dry extension 30mm, front stop time 0.9s~1.0s, rear stop time 0.9s~1.0s, swing amplitude 15mm~29mm, swing speed 54mm / s, line energy 245kj / cm~278kj / cm; Welding gun II: current 350A~360A, voltage 35V~36V, welding speed 2.8cm / min~3.0cm / cm, dry extension 32mm, front stop time 0.9s~1.0s, rear stop time 0.9s~1.0s, swing amplitude 15mm~29mm, swing speed 54mm / s, line energy 245kj / cm~278kj / cm; 5) Welding process: fix the positions of welding gun I and welding gun II respectively, adjust the inclination angle of the welding gun to 11°, keep the conductive nozzle 5mm and 7mm away from the upper end of the copper slider outlet, the longitudinal depth is 10mm~30mm and 28mm~55mm from the surface side, fill 5mm~8mm after breaking the arc, and then continue arc welding.

[0008] The advantages of the present invention are as follows: the present invention provides a feasible method for testing the brittle fracture resistance of welded joints for high-energy-line welding of structural thick steel plates, and is mainly applicable to single-pass welding forming processes under 200kj / cm-600kj / cm energy-line for 20mm-80mm thick steel plates. The present invention solves the problem that the coarse-grained area of ​​the "V" groove in high-energy-line welding is not linearly distributed in the past. By changing the groove form and optimizing the process parameters, the heat distribution structure in the groove is adjusted, and finally the coarse-grained area of ​​the welded joint is distributed in the ideal target form, thus realizing the testing of the brittle fracture resistance of the coarse-grained area in high-energy-line welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the arrangement of the water-cooled copper liner and the copper slider of the present invention; Figure 2 It is a detailed assembly diagram of the test board and copper liner of the present invention; Figure 3 It is a detailed assembly diagram of the water-cooled copper slider of the present invention; Figure 4 This is the layout diagram of the welding gun in the groove with a specification of 20mm~40mm of the present invention; Figure 5 This is a schematic diagram of a 20mm~40mm specification welding joint of the present invention; Figure 6This is the layout diagram of the welding gun in the groove with a specification of 40mm~80mm of the present invention; Figure 7 This is a schematic diagram of a 40mm~80mm specification welding joint of the present invention; Figure 8 This is the macroscopic acid etching image of the cross section of 40mm EH40-W200 of the present invention; Fig. 9 This is the macroscopic acid etching image of the cross section of 40mm EH40-W200 of the present invention; Fig.10 This is the macroscopic acid etching image of the cross section of 80mm EH40-W400 of the present invention; Fig.11 This is the macroscopic acid etching image of the cross section of 80mm EH40-W400 of the present invention.

[0010] Among them: 1-test plate A, 2-test plate B, 3-sliding clamping plate, 4-fixed clamping plate, 5-top screw knob, 6-water-cooled copper liner, 7-wedge block, 8-U-shaped horse plate, 9-groove, 10-water-cooled copper slider, 11-shielding gas connection hole, 12-cooling water supply hole, 13-cooling water return hole, 14-water-cooled slider fixing groove, 15-welding gun I, 16-welding wire I, 17-molten pool, 18-welding gun II, 19-welding wire II. DETAILED DESCRIPTION

[0011] The present invention is further described below with reference to the embodiments.

[0012] In the present invention, two test plates A1 and B2 are placed at a required spacing, an I-shaped groove 9 is selected, a sliding clamping plate 3 and a fixed clamping plate 4 with a top screw knob 5 are placed at both ends, a wedge block 7 and a U-shaped horse plate 8 are placed at the weld, a water-cooled copper slider 10 slides in a water-cooled slider fixing groove 14, and a protective gas connection hole 11, a cooling water supply hole 12, and a cooling water return hole 13 are provided on it; one or two of welding guns I 15 and II are selected according to requirements, and welding wires I 16 and II 19 are installed accordingly.

[0013] The process parameters of the 20mm-80mm structural thick steel plate welding method of the present invention are applicable to low-alloy structural steels of the same specification. The present solution is further described below through specific embodiments.

[0014] Example 1: Welding of 40 mm EH40-W200 steel plate, comprising the following steps: a. Prepare two 1000*250*40EH40-W200 test plates, namely test plate A1 and test plate B2, and use mechanical processing methods to process 0° grooves. Grind and clean the oil, rust and impurities within 10mm of the groove edge.

[0015] b. Prepare two pieces of 500*45*25 water-cooled copper gaskets with a groove width of 18mm, one piece of water-cooled copper slider with a groove width of 20mm, one piece of 100*40*12 EH40-W200 arc starting plate, and three pieces of EH40-W200 U-shaped horse plates.

[0016] c. Leave a 17mm gap to assemble the test plates, fix them with a U-shaped horse plate on the back, fix the copper gasket to the test plate tightly in the horse plate, and weld the arc-starting plate to the end of the test plate.

[0017] c. Select a water-cooled special welding gun I, φ1.6 conductive nozzle, φ1.6 connecting rod, and prepare φ1.6DW-S1LG high-energy welding wire. Adjust the cooling water flow rate to 11L / min and the lift to 45 meters.

[0018] d. Select 99.99% CO2 and adjust the protective gas flow rate to 25L / min.

[0019] e. Fix the welding gun position so that the conductive nozzle is 5mm above the air outlet of the copper slider and the depth is 1 / 2 of the plate thickness.

[0020] f. Adjust the front dwell time of the welding trolley to 0.9s, the rear dwell time to 0.9s, the swing amplitude to 27.5mm, the swing speed to 54mm / s, and the dry extension to 30mm.

[0021] g. Open the shielding gas and cooling water valves, start manual welding, break arc filling, fill the molten pool 17 (weld) 5mm, start automatic welding, adjust the welding current to 360A, and adjust the welding voltage to 36V. During welding, observe the state of the molten pool, adjust the welding gun to keep it at the axis of the groove, and adjust the welding gun angle by 11° to make the front and rear fusion ratios in the molten pool the same (the welding gun angle can be adjusted according to the actual molten pool state during welding).

[0022] h. After welding, press the stop button, turn off the protective gas after 2 minutes, turn off the cooling water after 5 minutes, remove the water-cooled copper slider and copper liner, and check the weld surface.

[0023] Example 2: Welding of 80 mm EH40-W400 steel plate, comprising the following steps: a. Prepare 2 test plates of 1000*250*80EH40-W400, perform 0° groove processing by mechanical processing method, and grind and clean the oil, rust and impurities within 10mm of the groove edge.

[0024] b. Prepare 2 pieces of 500*45*25 water-cooled copper gaskets with a groove width of 22mm, 1 piece of water-cooled copper slider with a groove width of 24mm, 1 piece of 100*80*18EH40-W400 arc starting plate, and 3 pieces of EH40-W400 U-shaped horse plates.

[0025] c. Leave a 21mm gap to assemble the test plates, fix them with a U-shaped horse plate on the back, fix the copper gasket to the test plate tightly in the horse plate, and weld the arc-starting plate to the end of the test plate.

[0026] c. Select a water-cooled special welding gun, φ1.6 conductive nozzle, φ1.6 connecting rod, and prepare φ1.6 high-energy welding wire DW-S50GTR and DW-S50GTF. Adjust the cooling water flow rate to 15L / min and the lift to 45 meters.

[0027] d. Select 99.99% CO2 and adjust the protective gas flow rate to 35L / min.

[0028] e. Fix the positions of welding gun I and welding gun II respectively so that the height of the conductive nozzle is 5mm and 7mm from the upper end of the copper slider's air outlet, the longitudinal depth is 30mm and 55mm from the surface side, and the distance between the two welding guns is 25mm.

[0029] f. Adjust the front dwell time of the welding carriage to 1s, the rear dwell time to 1s, the swing amplitude to 29mm, the swing speed to 54mm / s, the dry extension length of welding gun I to 30mm, and welding gun II to 32mm.

[0030] g. Open the shielding gas and cooling water valves, start manual welding, break arc filling, fill the molten pool to 8mm, start automatic welding, adjust welding gun I welding current to 360A, voltage to 36V, adjust welding gun II welding current to 360A, voltage to 36V. During welding, observe the state of the molten pool, adjust the welding gun to keep it at the axis of the groove, and adjust the angles of I and II by 11° to make the front and rear fusion ratios in the molten pool the same.

[0031] h. After welding, press the stop button, turn off the protective gas after 2 minutes, turn off the cooling water after 5 minutes, remove the water-cooled copper slider and copper liner, and check the weld surface.

[0032] Take the samples of Example 1-2 and test the 40mmEH40-W200 and 80mmEH40-W400 welded joints according to GB / T 2358-1994 "Test Method for Crack Tip Opening Displacement of Metallic Materials". The test results are shown in the following table:

[0033] Among them: BM-base metal; GCHAZ-coarse grain area.

[0034] As can be seen from the table above, with this solution, the notch position of the large-line energy welding sample is partially located in the coarse grain zone, so it also meets the conditions for the "detection of crack tip opening displacement in the coarse grain zone (GCHAZ) of the weld joint" test. Figure 8-11It can be seen that after the 40mm~80mm structural thick steel plate is welded by the above welding process, the cross-section microscopic inspection of the welded joint shows that the GCHAZ in the heat affected zone is distributed in a straight line area approximately perpendicular to the upper and lower surfaces of the steel plate. The demonstration results show that this welding process can meet the CTOD inspection requirements of the GCHAZ area.

Claims

1. A high-energy thick plate welding method that meets the CTOD inspection of the welding coarse grain zone, characterized in that: The steps include: 1) Preparation before welding: Remove the surface oil and oxide scale on one side of the groove of the steel plate, select I-type groove with an angle of 0°; use water-cooled copper pads on the back of the specimen and water-cooled copper sliders on the face, and use arc-starting plates of the same material. The length, width and height of the arc-starting plates are: 100*t*(12-18)mm, where t is the plate thickness; 2) Protective gas: 99.99% pure CO2; 3) Gas flow rate: 25L / min~35L / min; 4) Welding process: Leave a gap of 17mm-21mm at the root of the groove. The specific welding parameters are as follows: Current 330A~360A, voltage 33V~36V, welding speed 2.8cm / min~3.2cm / cm, dry extension 30mm-32mm, front stop time 0.8s~1.0s, rear stop time 0.8s~1.0s, swing amplitude 15mm~29mm, swing speed 54mm / s, wire energy 204kj / cm~278kj / cm; 5) Welding process: fix the welding gun position, adjust the welding gun tilt angle 10-11°, the conductive nozzle height is 5-7mm from the upper end of the copper slider air outlet, the longitudinal depth is 10mm~55mm from the surface side, the arc is broken and filled 5mm~8mm, and then continuous arc welding is performed.

2. A high-energy-input thick plate welding method that meets the CTOD inspection of the welding coarse-grained zone according to claim 1, characterized in that: The steps include: 1) Preparation before welding: The groove side of the steel plate is machined to remove surface oil and oxide scale, and an I-type groove is selected with an angle of 0°; a 500*45*25 water-cooled copper liner with a groove width of 18mm~22mm is used on the back of the specimen, and a water-cooled copper slider with a groove width of 20mm~24mm is used on the face, and an arc starter plate of the same material is 100*t*12; 2) Protective gas: 99.99% pure CO2; 3) Gas flow rate: 25L / min~35L / min; 4) Welding process: The groove uses a symmetrical I-type groove, a 17mm gap is left at the root of the groove, and single-wire EGW welding is used; the specific welding parameters are as follows: Current 330A~360A, voltage 33V~36V, welding speed 2.9cm / min~3.2cm / cm, dry extension 30mm, front stop time 0.8s~0.9s, rear stop time 0.8s~0.9s, swing amplitude 15mm~28mm, swing speed 54mm / s, wire energy 204kj / cm~268kj / cm; 5) Welding process: fix the welding gun position, adjust the welding gun tilt angle 10°, the height of the conductive nozzle is 5mm from the upper end of the copper slider outlet, the depth is 1 / 2 of the plate thickness, and the arc is broken and filled 5mm before continuous arc welding.

3. A high-heat input thick plate welding method that meets the CTOD inspection of the welding coarse grain zone according to claim 1, characterized in that: The steps include: 1) Preparation before welding: The groove side of the steel plate is machined to remove surface oil and oxide scale, and an I-type groove is selected with an angle of 0°; a 500*45*25 water-cooled copper liner with a groove width of 18mm~22mm is used on the back of the specimen, and a water-cooled copper slider with a groove width of 20mm~24mm is used on the face, and an arc starter plate of the same material is 100*t*18; 2) Protective gas: 99.99% pure CO2; 3) Gas flow rate: 35L / min; 4) Welding process: The groove uses a symmetrical I-type groove, a 21mm gap is left at the root of the groove, and double-wire EGW welding is used; the specific welding parameters are as follows: Welding gun I: current 350A~360A, voltage 35V~36V, welding speed 2.8cm / min~3.0cm / cm, dry extension 30mm, front stop time 0.9s~1.0s, rear stop time 0.9s~1.0s, swing amplitude 15mm~29mm, swing speed 54mm / s, line energy 245kj / cm~278kj / cm; Welding gun II: current 350A~360A, voltage 35V~36V, welding speed 2.8cm / min~3.0cm / cm, dry extension 32mm, front stop time 0.9s~1.0s, rear stop time 0.9s~1.0s, swing amplitude 15mm~29mm, swing speed 54mm / s, line energy 245kj / cm~278kj / cm; 5) Welding process: fix the positions of welding gun I and welding gun II respectively, adjust the inclination angle of the welding gun to 11°, keep the conductive nozzle 5mm and 7mm away from the upper end of the copper slider outlet, the longitudinal depth is 10mm~30mm and 28mm~55mm from the surface side, fill 5mm~8mm after breaking the arc, and then continue arc welding.

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