CN105081527A - Vertical butt joint automatic welding technological method for medium-thin 5% Ni steel plates - Google Patents

Abstract

The present invention relates to a vertical butt joint automatic welding process of 5% Ni steel medium thin plates, which comprises the following steps: a, two 5% Ni steel medium thin plates to be welded are opened with corresponding grooves on one side, and blunt edge thickness is left; b, two pieces of 5% Ni steel medium thin plates to be welded A Y-shaped groove is formed when the 5% Ni steel medium and thin plates that need vertical butt welding are assembled by spot welding, and an anti-deformation code plate is attached to the reverse side of the Y-shaped groove; c. Welding robots are used, and flux cored wire gas shielded welding is used. The "rectangular" trajectory swing welding is carried out in the Y-shaped groove welding bead, and there is no stop in the middle of each bead. The welding method is DC pulse welding and double-sided welding. treatment, and then carry out reverse welding; d, 5% Ni steel plate is not preheated before welding, and the interlayer temperature of each weld bead is controlled below 150 °C. It can ensure that the welds on the front and back of the 5% Ni steel medium and thin plates in the vertical butt joint position are fully penetrated under automatic welding, the thickness of each weld bead is appropriate, and the front and back welds are well formed, thereby achieving the purpose of efficient welding.

Description

A kind of vertical butt joint automatic welding process of 5% Ni steel medium and thin plates

technical field

The invention relates to the technical field of welding technology, in particular to a vertical butt joint automatic welding process for thin plates in 5% Ni steel.

Background technique

Domestic welding of low-temperature steels such as 5% Ni is mostly manual arc welding, and the welding power supply is AC power supply. According to the plate thickness and joint form, multi-pass welding, narrow welding bead, and small specification welding are used during welding. Due to the limitation of welding materials and welding line energy, there has never been any relevant research report on automatic welding of 5% Ni steel using domestic flux-cored welding wire in the vertical butt joint position. The traditional manual welding is not only cumbersome to operate, but also has the disadvantages of uneven product quality and poor stability due to manual operation, and there are also some potential safety hazards.

Normally, the droplet transfer form of the Ni-based flux-cored wire in the DC welding mode is mostly spray transfer. When welding in the vertical butt joint position, the weld metal has high viscosity and is not easy to spread to both sides of the groove and piles up in the middle of the weld. The case of high temperature is very prominent, and the reason is that the critical current value of the injection transition in the DC welding mode is too large, resulting in excessive heat input; in addition, the weld metal formed by the Ni-based flux-cored wire itself has a high viscosity. , the droplet metal under the vertical butt joint position cannot overcome the gravity and piles up in the next trip or in the middle, which eventually makes the molten pool uncontrollable, and even swing welding cannot be significantly improved. At the same time, there are also problems that the welding cannot penetrate, the weld seam is not well formed, and spatter is easily generated during the welding process.

Contents of the invention

The purpose of the present invention is to provide a kind of improved vertical butt joint automatic welding process of 5% Ni steel medium and thin plates, which can overcome the inability of automatic welding, low efficiency, inability of welding penetration and poor weld formation in the prior art insufficient.

In order to achieve the above object, the technical solution of the present invention is: a vertical butt joint automatic welding process for thin plates in 5% Ni steel, characterized in that: the process comprises the following steps: a, two 5% Ni that need to be welded The corresponding groove is opened on one side of the steel medium thin plate, and the thickness of the blunt side is left; b. Two pieces of 5% Ni steel medium thin plates that need vertical butt welding are assembled to keep the gap when spot welding, forming a Y-shaped groove, and corresponding to the root In the gap, an anti-deformation code plate is attached to the reverse side of the 5% Ni steel medium thin plate; c, using a welding robot, using a flux-cored wire gas shielded welding, performing "rectangular" trajectory swing welding in the Y-shaped groove weld bead, and in each There is no stop in the middle of the weld bead, and the welding method is DC pulse welding and double-sided welding. After the front welding is completed, the back root cleaning treatment is required, and then the back welding is performed; d, 5% Ni steel plate is not preheated before welding , The interlayer temperature of each weld bead is controlled below 150°C.

When in use, the groove of the present invention adopts a Y-shaped groove, and in the groove weld bead with appropriate gaps and blunt edges, and an anti-deformation code plate attached to the reverse side, the welding torch can perform a "rectangular" trajectory during the welding process of each weld bead on the front and back sides. Swing welding without stopping in the middle of each weld bead can ensure that the welds on the front and back of the 5% Ni steel medium sheet under the vertical butt joint position are fully penetrated under automatic welding, the thickness of each weld bead is appropriate, and the front and back welding The seam is well formed, there is very little spatter in the welding process, and the non-destructive and mechanical performance tests all meet the relevant requirements; at the same time, it can effectively improve the welding efficiency, thereby achieving the purpose of efficient welding.

Description of drawings

Fig. 1 is a schematic diagram of the groove type in an embodiment of the present invention.

Fig. 2 is a schematic diagram of weld bead layout and back root cleaning in an embodiment of the present invention.

Fig. 3 is a schematic diagram of the swing trajectory of the welding torch in an embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The symbols in the drawings are as follows: 1. Front bottoming bead, 2. Front filling bead, 3. Front capping bead, 4. Reverse bead, 5. Anti-deformation code plate, 65% Ni steel medium thin plate.

A kind of vertical butt joint automatic welding process of thin plates in 5% Ni steel of the present invention, its difference with the prior art is: described process comprises the following steps: a, two 5% Ni steels that need welding The corresponding groove is opened on one side of the thin plate, and the thickness of the blunt edge is left; b. Two pieces of 5% Ni steel medium thin plates that need to be butt-welded are kept in a gap when spot welding is assembled to form a Y-shaped groove, and the corresponding root gap, Add an anti-deformation code plate on the reverse side of the 5% Ni steel medium thin plate; c. Use a welding robot, use flux-cored wire gas shielded welding, and perform "rectangular" trajectory swing welding in the Y-shaped groove weld bead, and in each weld bead There is no stop in the middle, and the welding method is DC pulse welding and double-sided welding. Heat, the interlayer temperature of each weld bead is controlled below 150°C.

In step a, the thin plate in the 5% Ni steel refers to a steel plate with a thickness in the range of 10-20mm, and the thickness of the blunt edge of 1.5-2.5mm is left in the unilateral processing of the steel plate; the angle range of the groove corresponding to the unilateral opening is 25- 35°. In a more optimized way, a blunt edge thickness of 1.8-2.2 mm is left in the unilateral processing of the thin steel plate, and the angle range of the groove corresponding to the unilateral opening is 28-32°. In step b, the angle range of the Y-shaped groove is 50-70°, and the suitable groove range for the 5% Ni steel plate within the thickness range of 10-15mm is 50-60°, and the groove range for the 5% Ni steel plate within the thickness range of 16-20mm is The suitable groove range of 5% Ni steel plate is 60-70°, and the gap size of 2-3.5mm should be maintained during spot welding before welding; in step c, during welding, the dry elongation of welding wire should be kept between 13-15mm, The welding wire is in the center of each weld bead and ensure alignment, and the distance between the end of the welding wire and the arc starting point is 2-3mm. The "rectangular" trajectory swing welding in the Y-groove weld bead refers to that from the bottom pass to the cover weld bead, under the condition that the swing length of the welding torch in each weld bead is kept constant, the swing amplitude and the two sides are adjusted accordingly. Rectangular trajectory welding method with dwell time.

In step c, after the welding of each weld bead on the front side is completed, the anti-deformation code plate is removed and the root cleaning process is performed on the reverse side. The position of the arc-shaped groove corresponds to the gap. After the back-side cleaning process is completed, the welding torch continues to carry out "rectangular" track swing welding in the back-side weld bead formed by the arc-shaped groove. After the back-side bead is welded, the weld seam width is 17-18mm, the excess height is 3-4mm.

In step c, when welding, the weld bead is superimposed layer by layer, the bottom is the bottom bead, the middle is the filler bead, the top is the capping bead, and the slag removal treatment is required between the weld bead; after the reverse weld bead is welded Surface cleaning is also performed.

The swing length of the bottoming weld bead is 1.5mm, the swing amplitude is 2.5mm, the dwell time on both sides is 0.25s, the welding current is 115-125A, the welding voltage is 16.2-17.5V, and the welding speed is 0.32m/min;

The swing length of the filler bead is 1.5mm, the swing size is 4.5mm, the dwell time on both sides is 0.25s, the welding current is 125-140A, the welding voltage is 16.2-17.5V, and the welding speed is 0.35m/min;

The swing length of the cover weld bead is 2mm, the swing amplitude is 5.5mm, the dwell time on both sides is 0.2s, the welding current is 130-140A, the welding voltage is 16.2-17.5V, and the welding speed is 0.5m/min;

The swing length of the reverse weld bead is 1.5mm, the swing amplitude is 5mm, the dwell time on both sides is 0.25s, the welding current is 130-140A, the welding voltage is 16.2-17.5V, and the welding speed is 0.45m/min;

Ф1.2mm flux-cored wire is used for the welding of the above welds, and 98%Ar+2%O ₂ mixed gas is used as the shielding gas, and the gas flow rate is 18-19L/min.

When welding, DC pulse welding and the existing Ni-based (Ni-Cr-Mo alloy) flux cored wire, model TMS-5T are used as welding materials, and 98% Ar+2% O ₂ mixed gas is used as shielding gas. DC pulse welding is based on the original DC mode, using different heat input rates formed by pulses to make deep melting and solidification interactive, and finally the total average current is lower than the critical current value (current value from droplet transition to spray transition) In this case, a controlled injection transition of the molten pool is obtained. The pulse control transition technology has the advantages of improving welding heat input and spray transition, which can ensure that the Ni-based flux-cored wire droplet metal in the case of vertical butt joint can effectively overcome gravity and spread to both sides and depth of the groove, while improving deposition efficiency. In addition, the 98% Ar + 2% O ₂ mixed gas protection that matches the pulse control transition technology has the advantage that a small amount of oxygen is added to the argon gas. Since O ₂ is a surface active element, it can reduce the surface tension of the liquid metal and make the jet flow The critical current of the transition is reduced, the size of the droplet is refined, and the transfer characteristics of the droplet are improved. In addition, because the mixed gas has a certain oxidizing property, it can stabilize and control the position of the arc cathode spot, which can avoid the arc fluttering caused by the cathode spot swimming, the droplet transfer is unstable, the gas protection effect is destroyed, and the welding seam Irregular molding and generation of undercuts, lack of fusion, etc.

Correspondingly, the penetration test and radiographic test of the welds did not find excessive defects, which respectively met the assessment requirements of CB3958/-2004/II and CB/T3558-2011B II; the tensile strength of the welded joint was 576MPa, and the test temperature was -115℃ , the impact energy of the weld is 117J, the impact energy of the fusion line is 311J, the impact energy of 2mm outside the fusion line is 292J, and the impact energy of 5mm outside the fusion line is 301J. No defects have been found. After the corrosion test, no defects such as cracks and lack of fusion visible to the naked eye were found on the joint welds and the surface of the heat-affected zone of the macro-corrosion samples at a magnification of 800 times.

Example 1

As shown in Figure 1, a kind of vertical butt joint automatic welding process of 5% Ni steel medium thin plate, described 5% Ni steel medium thin plate thickness is 15mm:

1) The bevel on one side of the test plate is 30°, leaving a blunt edge thickness of 1.5-2.5mm;

2) There is a gap of 2-3.5mm when the test plate is assembled by spot welding;

3) An anti-deformation code plate is added on the reverse side to ensure the size of the gap.

The processing error of the blunt edge thickness of the test plate shall not exceed 1mm, and the gap size of 2-3mm shall be maintained during the spot welding assembly before welding and shall be maintained by attaching an anti-deformation code plate on the reverse side of the test plate. The spot welding assembly of the test plate group is also completed with Ni-based welding wire. The gap size of 2-3mm is maintained during the spot welding assembly before welding and is maintained by attaching an anti-deformation code plate on the reverse side of the test plate.

Shown in Fig. 2 and Fig. 3, comprise the specific welding steps of described test plate:

1) When welding, the dry elongation of the welding wire is kept between 13-15mm, the welding wire is in the center of each weld bead and the alignment is ensured, and the welding wire end is 2-3mm away from the arc starting point;

2) Make the welding torch carry out the "rectangular" track swing welding along the weld bead during the welding process of each weld bead, and do not stop in the middle of each weld bead;

3) The above welds are welded with domestically produced Ni-based (Ni-Cr-Mo alloy) Ф1.2mm flux cored wire, and 98%Ar+2% _O2 mixed gas is used as the shielding gas, and the gas flow is 18 -19L/min. The steel plate is not preheated before welding, and the temperature between the layers of each weld bead is controlled below 150°C, and slag cleaning is required between weld passes.

4) The weld bead layout and process parameters at the vertical butt joint during welding are shown in Figure 2 and Figure 3, and the process parameters of each weld bead are shown in the table below.

During the welding process of the robot, the operator calls the pre-written program or writes a new program through teaching. After the program is written and debugged, the reserved program is set, and the operation of the welding robot is controlled through the starting device.

Each weld bead in the groove of the 5% Ni steel test plate in the vertical butt joint position, through the gap assembly guarantee of the test plate before welding, the anti-deformation control in advance, combined with DC pulse welding, 98%Ar+2% _O2 under the protection of the mixed gas The reasonable selection of each process parameter finally ensures that in the case of double-sided welding, root cleaning on the back side, and slag cleaning between weld passes, the root of the weld joint is fully penetrated, and the weld beads on the front and back sides are well formed, and automatic welding simplifies the work. The process effectively improves the welding quality and production efficiency of low-temperature steel.

The DC pulse welding used uses the different heat input rates formed by the pulse to make deep melting and solidification interactive, and finally the molten pool is obtained when the total average current is lower than the critical current value (the current value from the droplet transition to the jet transition). Controlled jet transition. The O ₂ in the selected 98% Ar+2% O ₂ mixed gas protection has surface active elements, which can reduce the surface tension of the liquid metal, reduce the critical current for jet transition, refine the droplet size, and improve the melting efficiency. Droplet transition characteristics. The welding process adopted can significantly slow down the liquid metal dripping and overflowing of Ni-based welding consumables in the form of spray transition; promote it to spread more effectively to both sides and depth of the weld bead, and realize the rapid filling of deposited metal at the same time It can also ensure the quality of welded joints. All welds are fully penetrated, the thickness of each weld bead is appropriate, the front and back welds are well formed, and there is very little spatter in the welding process. The non-destructive and mechanical performance tests all meet the relevant requirements. It makes it possible to use domestically produced Ni-based flux-cored wire for automatic welding and popularization of medium and thin plate 5% Ni steel in the vertical butt joint position.

Example 2

A vertical butt joint automatic welding process for 5% Ni steel medium and thin plates, the thickness of the 5% Ni steel medium and thin plates is 13mm:

1) The bevel on one side of the test plate is 28°, leaving a blunt edge thickness of 1.8mm;

2) There is a gap of 2.8mm when the test plate is assembled by spot welding;

3) An anti-deformation code plate is added on the reverse side to ensure the size of the gap.

The processing error of the blunt edge thickness of the test plate shall not exceed 1mm, and the gap size of 2.8mm shall be maintained during the spot welding assembly before welding and shall be maintained by attaching an anti-deformation code plate on the reverse side of the test plate. The spot welding assembly of the test plate group is also completed with Ni-based welding wire. The gap size of 2.5mm is maintained during the spot welding assembly before welding and is maintained by attaching an anti-deformation code plate on the reverse side of the test plate.

The specific welding steps of the thin steel plate:

1) When welding, the dry elongation of the welding wire is kept between 13-15mm, the welding wire is in the center of each weld bead and the alignment is ensured, and the distance between the welding wire end and the arc starting point is 3mm;

2) Make the welding torch carry out the "rectangular" track swing welding along the weld bead during the welding process of each weld bead, and do not stop in the middle of each weld bead;

3) The above welds are welded with domestically produced Ni-based (Ni-Cr-Mo alloy) Ф1.2mm flux cored wire, and 98%Ar+2% _O2 mixed gas is used as the shielding gas, and the gas flow is 18 -19L/min. The steel plate is not preheated before welding, and the temperature between the layers of each weld bead is controlled below 150°C, and slag cleaning is required between weld passes.

The vertical butt joint automatic welding process for thin plates in 5% Ni steel of the present invention has the following advantages: 1) the different heat input rates formed by the DC pulse welding utilize the pulse to make deep melting and solidification interactively carried out, finally with the total average When the current is lower than the critical current value (the current value for changing from droplet transfer to spray transfer), controllable spray transfer of the molten pool is obtained. 2) The O2 in the selected 98%Ar+ ₂ % _O2 mixed gas protection has surface active elements, which can reduce the surface tension of liquid metal, reduce the critical current for jet transition, refine the droplet size, and improve droplet transfer characteristics. 3) The welding process adopted can significantly slow down the liquid metal dripping and overflowing of Ni-based welding consumables in the form of spray transition; promote it to spread more effectively to both sides and depth of the weld bead, and realize the rapid deposition of metal Filling can also ensure the quality of welded joints. 4) All welds are fully penetrated, the thickness of each weld bead is appropriate, the front and back welds are well formed, and there is very little spatter during the welding process. The non-destructive and mechanical performance tests all meet the relevant requirements. 5) It makes it possible to automatically weld 5% Ni steel plates in the vertical butt joint position using domestically produced Ni-based flux-cored welding wire.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be assumed that the specific implementation of the present invention is limited to the above descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deduction or replacement can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (7)

1. a kind of 5%Ni steel medium thin plate vertical butt joint automatic welding process, it is characterized in that: described processing method comprises the steps: a, two 5%Ni steel medium thin plates that need to be welded unilaterally open corresponding groove, And leave the blunt edge thickness; b. Two pieces of 5%Ni steel medium thin plates that need to be welded vertically shall retain a gap during spot welding assembly to form a Y-shaped groove and correspond to the root gap. In the 5% Ni steel medium thin plate Anti-deformation code plate is attached on the reverse side; c. Welding robot is used, flux-cored wire gas shielded welding is used, and "rectangular" track swing welding is performed in the Y-shaped groove weld bead, and no stop is made in the middle of each weld bead, and the welding method is direct current Pulse welding, double-sided welding forming, after the front welding is completed, the back root needs to be cleaned, and then the back welding is performed; d, 5% Ni steel medium and thin plates are not preheated before welding, and the temperature between the layers of each weld bead is controlled at 150 ℃ the following. 2. a kind of 5%Ni steel medium thin plate vertical butt joint automatic welding process according to claim 1, is characterized in that: in a step, described 5%Ni steel medium thin plate refers to the steel plate that thickness is in the scope of 10-20mm , The thickness of the blunt edge is 1.5-2.5mm in the unilateral processing of the steel plate; the angle range of the groove corresponding to the unilateral opening is 25-35°. 3. a kind of 5%Ni steel thin plate vertical butt joint automatic welding process according to claim 1, it is characterized in that: in step b, the Y-shaped groove angle range is 50-70 °, wherein 10-15mm plate thickness The suitable groove range for the 5%Ni steel plate within the range is 50-60°, and the suitable groove range for the 5%Ni steel plate within the thickness range of 16-20mm is 60-70°. Keep the gap size of 2-3.5mm; in step c, when welding, the dry elongation of the welding wire is kept between 13-15mm, the welding wire is in the center of each welding bead and the alignment is ensured, and the welding wire end is 2-3mm away from the arc starting point . 4. a kind of 5%Ni steel medium and thin plate vertical butt joint automatic welding process according to claim 1, it is characterized in that: in c step, after each weld bead of front side is welded, unloads anti-deformation code plate and carries out reverse side Root cleaning treatment, the back root cleaning treatment forms an arc-shaped groove with a width of 11-12mm and a depth of 3-4mm. The position of the arc-shaped groove corresponds to the gap. The "rectangular" trajectory swing welding is carried out in the reverse weld bead formed by the arc groove; when welding, the existing Ni-based (Ni-Cr-Mo alloy) flux cored wire, model TMS-5T is used as the welding material, 98 %Ar+2%O ₂ mixed gas is the protective gas. 5. a kind of 5%Ni steel thin plate vertical butt joint automatic welding process according to claim 1 is characterized in that: in the c step, during welding, the weld bead is superimposed layer by layer, the bottom is the bottom weld bead, and the middle part is The filling weld bead, the top is the cover weld bead, and the slag cleaning treatment is required between the weld bead; the surface cleaning is also carried out after the reverse weld bead is welded; the swing length of the bottom weld bead is 1.5mm, the swing size is 2.5mm, The dwell time on both sides is 0.25s, the welding current is 115-125A, the welding voltage is 16.2-17.5V, and the welding speed is 0.32m/min; The dwell time is 0.25s, the welding current is 125-140A, the welding voltage is 16.2-17.5V, and the welding speed is 0.35m/min; Both are 0.2s, the welding current is 130-140A, the welding voltage is 16.2-17.5V, and the welding speed is 0.5m/min; the swing length of the reverse weld bead is 1.5mm, the swing size is 5mm, and the dwell time on both sides is 0.25s. The welding current is 130-140A, the welding voltage is 16.2-17.5V, and the welding speed is 0.45m/min; the welding of the above welds uses Ф1.2mm flux-cored wire, and is equipped with 98%Ar+2%O ₂ mixed gas for Protective gas, gas flow is 18-19L/min. 6. A kind of 5%Ni steel medium thin plate vertical butt joint automatic welding process according to claim 2, characterized in that: the steel medium thin plate is left with a blunt edge thickness of 1.8-2.2mm in unilateral processing, and the corresponding slope is opened on one side The angle of the mouth ranges from 28-32°. 7. a kind of 5%Ni steel thin plate vertical butt joint automatic welding process according to claim 1, is characterized in that: in c step, " rectangle " track swing welding in the described Y-shaped groove bead refers to From the bottom pass to the cover pass, under the condition that the swing length of the welding torch in the weld bead is kept constant, the swing amplitude and the dwell time on both sides are adjusted accordingly. The rectangular trajectory welding method.