Vertical welding method for L921A high-strength steel butt jointed board

Abstract

The invention discloses an L921A high-strength steel butt joint plate vertical welding method. The method comprises the steps that welding grooves of two L921A high-strength steel plates are machined into double-V-shaped grooves; the truncated edges of the grooves of the two pieces to be welded are aligned, and the gap between the truncated edges of the two pieces to be welded is 2-5 mm; protective gas is introduced into the front surface and the back surface at the same time during front surface first-layer backing welding, and melting holes are formed in the front end of a weld pool during welding, so that the front surface and the back surface of a weld are formed during front surface first-layer backing welding. According to the vertical position welding method, in the welding process, carbon gouging, back gouging and grinding are not needed to be conducted on the back face to remove a carburized layer, the problem that carbon gouging causes carburization in a welding seam can be effectively solved, and therefore the internal quality and the welding efficiency of L921A high-strength steel welding are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of welding butt joints of L921A steel panels, and in particular relates to a vertical welding method for butt joints of L921A high-strength steel panels. Background Art

[0002] High-pressure and high-temperature shells have been widely used in recent years. Considering factors such as material consumption, high-strength steel has gradually replaced the main material of high-temperature and high-pressure shells. As we all know, high-strength steel has poor welding performance and is difficult to weld. Therefore, welding methods to improve the welding quality and welding efficiency of this material have become the main research object.

[0003] L921A steel has been successfully selected as an optional material for high-temperature and high-pressure shells due to its excellent material properties. However, this material is difficult to weld in vertical welding. At present, the traditional butt welding method of vertical welding of this material welding plate adopts the method of front welding, back carbon planing and root cleaning, and then welding the back side. There are generally the following problems:

[0004] (1) Since carbon rods are used for carbon planing and root cleaning, the carbon planing will not only damage the welded weld, but also significantly remove the main body material, which increases a lot of extra welding. Since vertical welding is difficult and the welding quality is not easy to control, it has a great impact on the welding efficiency and the internal quality of the welding.

[0005] (2) After carbon planing, there is a carburized layer on the material body and the weld. The carbon planed area needs to be manually polished to remove the carburized layer on the weld surface. In order to ensure the internal quality of the weld, non-destructive testing is also required to check for defects before welding the reverse weld. The carbon planing and polishing workload is large during the entire welding process, and the welding efficiency is low.

[0006] The current vertical welding method has a complicated process and high costs in terms of man-hours, kinetic energy usage, and material consumables, which is not conducive to improving the welding quality and efficiency of L921A high-strength steel. Summary of the invention

[0007] The invention breaks the traditional welding method of L921A high-strength steel plate butt weld, and provides a L921A high-strength steel plate butt weld method which improves welding efficiency and quality.

[0008] To achieve the above object, the present invention provides a method for vertical welding of L921A high-strength steel butt joint plates, comprising the following steps:

[0009] 1) Process the welding grooves of two L921A high-strength steel plates into double V-shaped grooves;

[0010] 2) Align the blunt edges of the grooves of the two pieces to be welded, and the gap between the blunt edges of the two pieces to be welded is 2 to 5 mm;

[0011] 3) When welding the first layer of the front backing, the shielding gas is passed to both the front and back sides, and a molten hole is formed at the front end of the weld pool during welding, so that the weld is formed on both sides when welding the first layer of the front backing.

[0012] Furthermore, in the step 1), the processing groove angle is 50° to 60°, and the blunt edge is 1 to 2 mm.

[0013] Furthermore, in the step 3), the first layer of the front base welding is TIG welding, and a φ2.4mm RsWM60S-T welding wire is used, and the shielding gas is 99.999% argon; the front weld width is 4-7mm; the back weld thickness is 1-2mm and the width is 4-6mm.

[0014] Furthermore, in the step 3), when performing the first layer of back welding on the front side, the front side gas flow rate is 13-18 L / min, the back side gas flow rate is 8-12 L / min, the welding current is 120-180 A, the voltage is 12-15 V, and the welding speed is 5-10 cm / min.

[0015] Furthermore, the steps also include front filling welding and capping welding, the second layer of filling welding adopts TIG welding, and uses a φ2.4mm RsWM60S-T welding wire, and the shielding gas is 99.999% argon; the welding current is 100-110A, the voltage is 21-22V, the welding speed is 80-100mm / min, the thickness of the weld is 1-2mm, and the width is 6-9mm;

[0016] The third layer of filling welding and the fourth layer of cap welding are both pulsed MAG welding, the shielding gas is 95% Ar + 5% CO2, and the φ1.2mm brand RsWM60S welding wire is used; the gas flow rate of the third layer of filling welding and the fourth layer of cap welding is 15-20L / min, the filling current during filling welding is 90-130A, the voltage is 17-21V, and the welding speed is 6-10cm / min, and the cap current during cap welding is 120-130A, the voltage is 19-21V, and the welding speed is 8-10cm / min; the width of each single weld of pulse MAG welding is 6-10mm and the thickness is 2-3mm; during welding, the inter-pass temperature of the weld is 100-120℃.

[0017] Furthermore, the steps also include back filling welding and capping welding, the second layer of filling welding adopts TIG welding, and adopts φ2.4mm brand RsWM60S-T welding wire, the shielding gas is 99.999% argon; the welding current is 100-110A, the voltage is 21-22V, the welding speed is 80-100mm / min, the thickness of the weld is 1-2mm, and the width is 6-9mm;

[0018] The third layer of filling welding and the fourth layer of cap welding are both pulsed MAG welding, the shielding gas is 95% Ar + 5% CO2, and the φ1.2mm brand RsWM60S welding wire is used; the gas flow rate of the third layer of filling welding and the fourth layer of cap welding is 15-20L / min, the filling current during filling welding is 90-130A, the voltage is 17-21V, and the welding speed is 6-10cm / min, and the cap current during cap welding is 120-130A, the voltage is 19-21V, and the welding speed is 8-10cm / min; the width of each single weld of pulse MAG welding is 6-10mm and the thickness is 2-3mm; during welding, the inter-pass temperature of the weld is 100-120℃.

[0019] Furthermore, the reverse sides of the two pieces to be welded are positioned and fixed by using a cama plate to ensure that the misalignment at the joint of the two pieces to be welded is not greater than 1 mm.

[0020] Furthermore, arc striking and arc extinguishing plates with the same groove and the same plate thickness are installed at the arc striking and arc extinguishing ends of the welds of the two pieces to be welded.

[0021] Furthermore, the TIG welding adopts a welding device of model WsM-400, and the pulse MAG welding adopts a welding device of model YD-500GL5HN.

[0022] Furthermore, in the step 3), before welding, the welding area and the surrounding area are preheated; the first layer of the front bottom weld joint is preheated 8 to 10 mm below the weld to 100 to 150°C.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The vertical welding method of the present invention improves welding efficiency and quality, and the weld root is well fused. Compared with the traditional welding method, the welding efficiency is increased by more than 2 times, the consumables cost is reduced by 1 times, and the labor cost is reduced by 50%;

[0025] 2) In the vertical welding method of the present invention, there is no need to perform carbon planing and root cleaning and grinding on the reverse side to remove the carburized layer during welding, which can effectively prevent the carburization problem caused by carbon planing in the weld, thereby improving the internal quality and welding efficiency of L921A high-strength steel welding;

[0026] 3) During the welding process, the welding heat input is effectively controlled to ensure the fusion ratio of the weld, the interlayer temperature of the weld is strictly controlled, and a welding process for vertical welding and butt-jointing of L921A high-strength steel plates is developed. The single-sided welding and double-sided forming welds have better front and back forming, and have good mechanical properties such as tensile and bending, and meet the impact requirements of high temperature and high pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the invented jigsaw puzzle structure;

[0028] Figure 2 Schematic diagram of assembling Kama board for inventing jigsaw puzzle;

[0029] Figure 3 A schematic diagram of the arc-initiating and arc-extinguishing plate assembled with the invented panels;

[0030] Figure 4 Weld bead layout diagram for invented welds. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail in conjunction with specific embodiments and drawings to facilitate a clearer understanding of the present invention, but they do not constitute a limitation to the present invention.

[0032] 1. Material selection

[0033] The two pieces to be welded are made of high-strength steel with a grade of L921A and a thickness of 12mm. This material has high mechanical properties, especially under high temperature and high pressure conditions. However, this material has high requirements for the control of welding line energy during the welding process. The welding process is relatively complicated and the interpass temperature should be strictly controlled during the welding process.

[0034] TIG welding uses φ2.4mm RsWM60S-T welding wire with 99.999% argon, and pulse MAG welding uses φ1.2mm RsWM60s welding wire with 95% Ar+5% cO2. The linear expansion coefficient of this welding material is close to that of L921A high-strength steel. It is preheated to 100-150℃ before welding to remove oil, water, etc., and stress relief heat treatment is performed after welding. After the weld is formed, the strength is high, the pressure resistance is high, and the crack resistance is good. The basic low-hydrogen type welding wire is selected to effectively remove harmful elements in the weld during welding, reduce the hydrogen content of the weld, and improve the welding quality of the weld.

[0035] TIG welding uses welding equipment model WsM-400, and pulse MAG welding uses welding equipment model YD-500GL5HN.

[0036] In order to improve welding efficiency and reduce material waste, the welding equipment of the present invention is selected for comparison under the same welding process conditions.

[0037] Example 1

[0038] The welding equipment selected was pulse welding (YD-500GL5HN), welding wire brand RsWM60S, diameter 1.2 mm, welding speed 6-10 cm / min, welding current 90-130 A, voltage 17-21 V, mixed shielding gas 95% Ar+5% CO2 flow rate 15-20 L / min, and three groups of test blocks were welded.

[0039] Example 2

[0040] The welding equipment selected was (NBC-500P plus), welding wire brand RsWM60S, diameter 1.2 mm, welding current 90-130 A, voltage 17-21 V, welding speed 6-10 cm / min, mixed shielding gas 95% Ar+5% CO2 flow rate 20 L / min, and three groups of test blocks were welded.

[0041] Example 3

[0042] The welding equipment selected was pulse welding (YD-500GL5HN), welding wire brand ER50-6, diameter 1.2 mm, welding current 90-130 A, voltage 17-21 V, welding speed 6-10 cm / min, mixed shielding gas 95% Ar+5% CO2 flow rate 20 L / min, and three groups of test blocks were welded.

[0043] Example 4

[0044] The welding equipment selected was (NBC-500P plus), welding wire brand ER50-6, diameter 1.2 mm, welding current 90-130 A, voltage 17-21 V, welding speed 6-10 cm / min, mixed shielding gas 95% Ar+5% CO2 flow rate 20 L / min, and three groups of test blocks were welded.

[0045] Table 1

[0046]

[0047] According to Table 1, with the same welding parameters, the equipment and welding parameters selected in Example 1, i.e., the present invention, all meet the requirements and are better than other solutions.

[0048] 2. Preparation before welding

[0049] like Figure 1 As shown in FIG. 1 , the welding grooves of two L921A high-strength steel plates are processed into double V-shaped grooves with a processing groove angle of 50° to 60° and a blunt edge of 1 to 2 mm; Figure 3 As shown, arc striking and extinguishing plates 2 with the same groove and plate thickness are installed at the arc striking and extinguishing ends of the welds of the two pieces to be welded to ensure the welding quality of the arc striking and arc extinguishing welds.

[0050] Grind and align the blunt edges of the grooves of the two pieces to be welded, and the gap between the blunt edges of the two pieces to be welded is 2 to 5 mm; Figure 2 The reverse sides of the two pieces to be welded are positioned and fixed by a cama plate 1 to ensure that the misalignment at the joint of the two pieces to be welded is not greater than 1 mm.

[0051] 3. Welding process

[0052] like Figure 4As shown, the number of front welding passes is 4 layers, the number of back welding passes is 3 layers, and the vertical butt welding process adopts the bottom-up welding method, as follows:

[0053] Before welding, preheat the welding area and surrounding areas, which can not only reduce the cooling rate of the weld, but also reduce the welding stress; preheat the first layer of base weld on the front side 8 to 10 mm below the weld joint to 100 to 150 ° C.

[0054] The first layer of backing welding on the front side adopts TIG welding. During the first layer of backing welding, shielding gas is passed to both the front and back sides, and a molten hole is formed at the front end of the weld pool during welding, so that the weld is formed on both sides during the first layer of backing welding on the front side. After welding, no carbon planing is required to clean the root on the back side. Passing shielding gas to the weld pool can prevent the formation of pores and inclusions in the molten pool during the solidification process, thereby preventing defects such as cracks.

[0055] When welding the first layer of the front side, the front side gas flow is 13-18L / min, the back side gas flow is 8-12L / min, the welding current is 120-180A, the voltage is 12-15V, and the welding speed is 5-10cm / min; the front side weld width is 4-7mm; the back side weld thickness is 1-2mm and the width is 4-6mm.

[0056] The second layer of filling welding on the front side adopts TIG welding, and uses φ2.4mm RsWM60S-T welding wire, and the shielding gas is 99.999% argon; the welding current is 100-110A, the voltage is 21-22V, the welding speed is 80-100mm / min, the thickness of the weld is 1-2mm, and the width is 6-9mm;

[0057] The third layer filling welding and the fourth layer cap welding on the front side are both pulsed MAG welding, the shielding gas is 95% Ar + 5% CO2, and the φ1.2mm brand RsWM60S welding wire is used; the gas flow rate of the third layer filling welding and the fourth layer cap welding is 15-20L / min, the filling current during filling welding is 90-130A, the voltage is 17-21V, and the welding speed is 6-10cm / min, and the cap welding current is 120-130A, the voltage is 19-21V, and the welding speed is 8-10cm / min; the single pass of each weld of pulse MAG welding is 6-10mm and the thickness is 2-3mm; during the welding process, the interpass temperature of the weld is 100-120℃.

[0058] The second layer of back-side filling welding adopts TIG welding, and uses φ2.4mm RsWM60S-T welding wire, and the shielding gas is 99.999% argon; the welding current is 100-110A, the voltage is 21-22V, the welding speed is 80-100mm / min, the thickness of the weld is 1-2mm, and the width is 6-9mm;

[0059] The third layer filling welding and the fourth layer cap welding on the back side are both pulsed MAG welding, the shielding gas is 95% Ar + 5% CO2, and the φ1.2mm brand RsWM60S welding wire is used; the gas flow rate of the third layer filling welding and the fourth layer cap welding is 15-20L / min, the filling current during filling welding is 90-130A, the voltage is 17-21V, and the welding speed is 6-10cm / min, and the cap current during cap welding is 120-130A, the voltage is 19-21V, and the welding speed is 8-10cm / min; the width of each single weld of pulse MAG welding is 6-10mm and the thickness is 2-3mm; during welding, the inter-pass temperature of the weld is 100-120℃.

[0060] 4. Welding quality inspection

[0061] The visual inspection of the front and back sides of the weld shows that the weld has good shape, without conventional defects such as undercut, pores, lack of fusion, cracks, etc. The non-destructive RT inspection shows that the internal quality of the weld is also good and without any defects. The butt-jointed plate welds are sampled for tensile, impact, bending, macro, micro, fatigue and other mechanical property tests. The test results show that they all meet the welding process requirements of L921A high-strength steel.

Claims

1. A method for vertical welding of L921A high-strength steel butt joint plates, characterized in that: The steps include: 1) Process the welding grooves of two L921A high-strength steel plates into double V-shaped grooves; 2) Align the blunt edges of the grooves of the two pieces to be welded, and the gap between the blunt edges of the two pieces to be welded is 2 to 5 mm; 3) When performing the first backing welding on the front side, the shielding gas is passed to both the front side and the back side at the same time, and a molten hole is formed at the front end of the weld pool during welding, so that the weld is formed on both sides when performing the first backing welding on the front side.

2. According to claim 1, the method for vertical welding of L921A high-strength steel butt joint plates is characterized by: In the step 1), the processing groove angle is 50° to 60°, and the blunt edge is 1 to 2 mm.

3. According to claim 1, the method for vertical welding of L921A high-strength steel butt joint plates is characterized by: In the step 3), the first layer of the front backing welding is TIG welding, and a φ2.4mm RsWM60S-T welding wire is used, and the shielding gas is 99.999% argon; the front weld width is 4-7mm; the back weld thickness is 1-2mm and the width is 4-6mm.

4. According to claim 1, the method for vertical welding of L921A high-strength steel butt joint plates is characterized by: In the step 3), when performing the first layer of back welding on the front side, the front side gas flow rate is 13-18 L / min, the back side gas flow rate is 8-12 L / min, the welding current is 120-180 A, the voltage is 12-15 V, and the welding speed is 5-10 cm / min.

5. According to claim 1, the method for vertical welding of L921A high-strength steel butt joint plates is characterized by: The steps also include front filling welding and capping welding, the second layer of filling welding adopts TIG welding, and adopts φ2.4mm brand RsWM60S-T welding wire, the shielding gas is 99.999% argon; the welding current is 100-110A, the voltage is 21-22V, the welding speed is 80-100mm / min, the thickness of the weld is 1-2mm, and the width is 6-9mm; The third layer of filling welding and the fourth layer of cap welding are both pulsed MAG welding, the shielding gas is 95% Ar + 5% CO2, and the φ1.2mm brand RsWM60S welding wire is used; the gas flow rate of the third layer of filling welding and the fourth layer of cap welding is 15-20L / min, the filling current during filling welding is 90-130A, the voltage is 17-21V, and the welding speed is 6-10cm / min, and the cap current during cap welding is 120-130A, the voltage is 19-21V, and the welding speed is 8-10cm / min; the width of each single weld of pulse MAG welding is 6-10mm and the thickness is 2-3mm; during welding, the inter-pass temperature of the weld is 100-120℃.

6. The method for vertical welding of L921A high-strength steel butt joint plates according to claim 1 is characterized in that: The steps also include back filling welding and capping welding, the second layer of filling welding adopts TIG welding, and adopts φ2.4mm brand RsWM60S-T welding wire, the shielding gas is 99.999% argon; the welding current is 100-110A, the voltage is 21-22V, the welding speed is 80-100mm / min, the thickness of the weld is 1-2mm, and the width is 6-9mm; The third layer of filling welding and the fourth layer of cap welding are both pulsed MAG welding, the shielding gas is 95% Ar + 5% CO2, and the φ1.2mm brand RsWM60S welding wire is used; the gas flow rate of the third layer of filling welding and the fourth layer of cap welding is 15-20L / min, the filling current during filling welding is 90-130A, the voltage is 17-21V, and the welding speed is 6-10cm / min, and the cap current during cap welding is 120-130A, the voltage is 19-21V, and the welding speed is 8-10cm / min; the width of each single weld of pulse MAG welding is 6-10mm and the thickness is 2-3mm; during welding, the inter-pass temperature of the weld is 100-120℃.

7. According to claim 1, the method for vertical welding of L921A high-strength steel butt joint plates is characterized by: The reverse sides of the two pieces to be welded are positioned and fixed by a cama plate to ensure that the misalignment of the two pieces to be welded at the joint is not greater than 1 mm.

8. The method for vertical welding of L921A high-strength steel butt joint plates according to claim 1 is characterized in that: Arc striking and extinguishing plates with the same groove and the same plate thickness are installed at the arc striking and extinguishing ends of the welds of the two pieces to be welded.

9. The method for vertical welding of L921A high-strength steel butt joint plates according to claim 5, characterized in that: The TIG welding adopts a welding device of model WsM-400, and the pulse MAG welding adopts a welding device of model YD-500GL5HN.

10. The method for vertical welding of L921A high-strength steel butt joint plates according to claim 1, characterized in that: In the step 3), before welding, the welding area and the surrounding area are preheated; the first layer of the front bottom welding seam joint is preheated 8 to 10 mm below the weld to 100 to 150°C.

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