阅读说明：本技术 舱壁下墩与双层底的高应力区域全熔透角焊缝的焊接方法 (Welding method for full penetration fillet weld of bulkhead lower pier and double-layer bottom high-stress area ) 是由 李勇 刘勇 潘秦 蔡莼 周福斌 顾振强 黄雪强 赵立苏 于 2020-05-28 设计创作，主要内容包括：本发明公开了舱壁下墩与双层底的高应力区域全熔透角焊缝的焊接方法,包括：对槽型舱壁下墩的正面进行坡口加工；对下墩斜板与双层底板两边及坡口周围20mm范围内进行清理；对角焊缝进行焊接；对槽型舱壁下墩的背面采用碳弧气刨方式清根,形成窄而深的U形坡口；U形坡口碳刨后修整坡口,并打磨；焊前清除U形坡口及两侧区域20mm范围内水分、油锈及氧化物；焊接电弧以碳刨根部焊缝为中心进行斜圆圈形摆动,由双数焊工分中对称进行焊接。本发明解决了现有技术中深熔焊焊缝熔深不够,难以满足角焊缝根部无焊接微裂纹缺陷要求的问题。(The invention discloses a welding method of a full penetration fillet weld of a bulkhead lower pier and a high-stress area of a double-layer bottom, which comprises the following steps: performing groove machining on the front surface of the lower pier of the tank bulkhead; cleaning the lower pier sloping plate, two sides of the double-layer bottom plate and the periphery of the groove within 20 mm; welding the diagonal weld; back chipping of the lower pier of the tank bulkhead in a carbon arc gouging mode to form a narrow and deep U-shaped groove; c, finishing and polishing the groove after the U-shaped groove is carbon-planed; removing water, oil rust and oxides within the range of 20mm in the U-shaped groove and two side areas before welding; the welding arc performs inclined circular swing by taking the welding seam at the root part of the carbon plane as the center, and welding is performed symmetrically in a double-number welding process. The invention solves the problems that in the prior art, the weld penetration of deep fusion welding is insufficient, and the requirement of no welding microcrack at the root part of a fillet weld is difficult to meet.)

1. The welding method of the full penetration fillet weld of the bulkhead lower pier and the high stress area of the double-layer bottom is characterized by comprising the following steps of:

step S1, performing groove processing on the front surface of the lower pier of the tank type bulkhead to form an angle weld between the lower pier inclined plate and the double-layer bottom plate, wherein the groove is a K-shaped groove;

step S2, cleaning the lower pier sloping plate, two sides of the double-layer bottom plate and the periphery of the groove within 20 mm;

step S3, welding the diagonal weld;

step S4, back chipping is carried out on the back of a lower pier of the tank type bulkhead in a carbon arc gouging mode to form a narrow and deep U-shaped groove;

step S5, the angle of the U-shaped groove is 45 degrees, the length of the welding wire reaches the root of the welding seam of the carbon planing part, and the groove is trimmed and polished after the carbon planing of the U-shaped groove;

step S6, removing moisture, oil rust and oxides in the range of 20mm of the U-shaped groove and the two side areas before welding;

and step S7, the downward inclination angle of the welding gun to the welding direction is 70-80 degrees, the angle of the welding gun to the bottom plate is 25-30 degrees, the welding wire points to the included angle formed by the first layer of welding line and the workpiece bottom plate, the welding arc performs inclined circular ring-shaped swing by taking the welding line of the carbon root part as the center, and the welding is performed symmetrically in the double-number welding process.

2. The method of welding a full penetration fillet weld between a lower bulkhead pier and a high stress area of a double bottom according to claim 1, wherein the cleaning in step S2 comprises: and (4) polishing and welding the truncated edges of the grooves, and removing oil rust, moisture and impurities until the metallic luster is exposed.

3. The method for welding the full penetration fillet weld between the lower bulkhead pier and the high stress area of the double-layer bottom according to claim 1, wherein in the step S3, a welding gun is uniformly arranged from right to left along with the formation of a molten pool in the welding process, and the downward inclination angle between the welding gun and the welding direction is 70-80 degrees; the welding wire points to the welding angle between the welding bead of the bottom layer and the horizontal plate, and oblique sawtooth welding or transverse small-swing manual welding is carried out;

slag is cleaned in the welding process, the slag is applied to successive welding layers, adjacent welding joints are staggered by 10mm, a crater area after welding is interrupted in each layer of welding pass is cleaned, and the size of a welding leg of a full penetration fillet weld is ensured to be consistent from top to bottom.

4. The method of welding a full penetration fillet weld between a lower bulkhead pier and a high stress area of a double bottom according to claim 1, wherein in step S3, the welding specification is adjusted by: the welding current is 240-280A, the arc voltage is 25-32V, and the advancing speed is 370-520 mm/min.

5. The method of claim 1, wherein in step S7, the first layer is welded at a slower speed to increase the thickness of the primer layer, the second layer is welded immediately after the first layer is finished, and two welders pay attention to the fact that the joint is 30-50mm away from each other and does not stay at the same arc extinguishing point when welding the same weld.

6. The method for welding a full penetration fillet weld between a lower bulkhead pier and a high stress area of a double-layer bottom according to claim 1, wherein in the step S7, the welding current during bottoming is not more than 240A; the interlayer temperature is controlled at 200 ℃ in the welding process; the slag is cleaned in the welding process, the slag is applied to successive welding layers, an arc pit area after welding is interrupted in each layer of welding pass is cleaned, and the sizes of welding feet of the full penetration fillet weld are ensured to be consistent from top to bottom.

Technical Field

The invention relates to the technical field of welding, in particular to a method for welding a full penetration fillet weld of a bulkhead lower pier and a high-stress area of a double-layer bottom.

Background

In the process of manufacturing and assembling ships, ocean engineering and other steel structures, welding operation is often needed to be carried out on the assembly bodies for connection or fixation, and particularly in the field of hull manufacturing, due to the fact that the structures of the lower piers of the tank bulkheads and the double-layer bottom welding fillet weld areas of the hulls are large and thick, very wide and deep welding seams are often needed to be welded. Usually, a multi-layer multi-pass deep penetration fusion welding method is adopted for welding.

The deep fusion welding is a welding method for obtaining a large-fusion deep welding bead by adopting a certain welding process, and the English name is defined as follows: the deep fusion welding seam belongs to PJP (Partial Joint penetration), namely two base materials are not completely connected through welding, the penetration reaches or approaches 70%, generally refers to a fillet weld, the thickness of a root 1/3 can be reserved, the root reserved in deep fusion welding is generally large and 6-8 mm, and back surfaces do not need to be back-gouged. According to the field practice, the problem that penetration is insufficient is easily caused in the welding process due to the fact that roots of deep fusion welding are large, ultrasonic detection finds that microcrack defects occur at the root parts of welding seams of the deep fusion welding, the severe consequence of direct fracture at the welding seams can be caused, so that great potential safety hazards exist in ship structure products, meanwhile, a large amount of rework repair cost is generated, as shown in figure 2, at present, a better overcoming method does not exist for the moment aiming at the defects, and the potential safety hazards of a welding structure caused by the defect that the penetration of the root parts of fillet welding seams is insufficient are to be solved urgently.

Disclosure of Invention

The invention aims to provide a method for welding a full penetration fillet weld between a lower pier of a bulkhead and a high-stress area of a double-layer bottom, and solves the problems that in the prior art, a deep fusion welding weld has insufficient penetration and is difficult to meet the requirement of no welding microcrack at the root of the fillet weld.

The technical scheme for realizing the purpose is as follows:

the welding method of the full penetration fillet weld of the bulkhead lower pier and the high stress area of the double-layer bottom comprises the following steps:

step S1, performing groove processing on the front surface of the lower pier of the tank type bulkhead to form an angle weld between the lower pier inclined plate and the double-layer bottom plate, wherein the groove is a K-shaped groove;

step S2, cleaning the lower pier sloping plate, two sides of the double-layer bottom plate and the periphery of the groove within 20 mm;

step S3, welding the diagonal weld;

step S4, back chipping is carried out on the back of a lower pier of the tank type bulkhead in a carbon arc gouging mode to form a narrow and deep U-shaped groove;

step S5, the angle of the U-shaped groove is 45 degrees, the length of the welding wire reaches the root of the welding seam of the carbon planing part, and the groove is trimmed and polished after the carbon planing of the U-shaped groove;

step S6, removing moisture, oil rust and oxides in the range of 20mm of the U-shaped groove and the two side areas before welding;

and step S7, the downward inclination angle of the welding gun to the welding direction is 70-80 degrees, the angle of the welding gun to the bottom plate is 25-30 degrees, the welding wire points to the included angle formed by the first layer of welding line and the workpiece bottom plate, the welding arc performs inclined circular ring-shaped swing by taking the welding line of the carbon root part as the center, and the welding is performed symmetrically in the double-number welding process.

Preferably, in step S2, the cleaning includes: and (4) polishing and welding the truncated edges of the grooves, and removing oil rust, moisture and impurities until the metallic luster is exposed.

Preferably, in step S3, the welding gun is uniformly moved from right to left along with the formation of the molten pool during the welding process, and the downward inclination angle of the welding gun to the welding direction is 70 to 80 degrees; the welding wire points to the welding angle between the welding bead of the bottom layer and the horizontal plate, and oblique sawtooth welding or transverse small-swing manual welding is carried out;

slag is cleaned in the welding process, the slag is applied to successive welding layers, adjacent welding joints are staggered by 10mm, a crater area after welding is interrupted in each layer of welding pass is cleaned, and the size of a welding leg of a full penetration fillet weld is ensured to be consistent from top to bottom.

Preferably, in step S3, the welding specification is adjusted: the welding current is 240-280A, the arc voltage is 25-32V, and the advancing speed is 370-520 mm/min.

Preferably, in step S7, the speed of the first layer may be slowed down to increase the thickness of the priming layer, the second layer is welded immediately after the first layer is finished, and when two welders weld the same welding line, the two welders pay attention to the fact that the joints are staggered by 30-50mm and do not stay at the same arc extinguishing point.

Preferably, in step S7, the welding current at the time of priming does not exceed 240A; the interlayer temperature is controlled at 200 ℃ in the welding process; the slag is cleaned in the welding process, the slag is applied to successive welding layers, an arc pit area after welding is interrupted in each layer of welding pass is cleaned, and the sizes of welding feet of the full penetration fillet weld are ensured to be consistent from top to bottom.

The invention has the beneficial effects that: the invention ensures the consistency of the sizes of the weld leg of the front-side welding full-fusion welding fillet weld; the back welding adopts a carbon arc gouging process back chipping mode, the problem of microcrack caused by poor fusion of roots in the welding process is solved, the quality of a welding seam is well stabilized through the selection of the shape requirement of the root of the groove, the angle of the groove and the angle of a welding gun after back chipping and the need of observing process measures in the welding process, the production efficiency and the production quality are improved, and the labor intensity is reduced.

Drawings

FIG. 1 is a flow chart of a method of the present invention for welding a full penetration fillet weld of a lower bulkhead pier to a double bottom high stress area;

FIG. 2 is a schematic view of an insufficient penetration of a deep penetration weld;

FIG. 3 is a schematic view of a back groove back gouging process;

FIG. 4 is a schematic diagram of the bevel angle of the carbon gouging with a bevel on the back side;

fig. 5 is a centered symmetrical welding sequence.

Detailed Description

The invention will be further explained with reference to the drawings.

Referring to fig. 1, the method for welding the full penetration fillet weld of the lower pier of the bulkhead and the high stress area of the double-layer bottom of the invention comprises the following steps:

firstly, front welding:

and step S1, performing groove processing on the front surface of the lower pier of the tank bulkhead to be welded, and cutting a groove by using a semi-automatic cutting machine to form an angle weld between the lower pier inclined plate and the double-layer bottom plate, wherein the groove is in a K-shaped groove form.

And step S2, cleaning the lower pier sloping plate, two sides of the double-layer bottom plate and the periphery of the groove within the range of 20mm, polishing and welding the truncated edge of the groove, and removing oil rust, moisture and impurities until the metallic luster is exposed.

Step S3, flux-cored wire CO2 (carbon dioxide) gas shielded arc welding is adopted for welding diagonal welds by FCAW (flux-cored-shielded arc welding), wherein the welding material is A5.20E71T-1C, and the diameter of the welding wire is phi 1.2 mm. And, during welding, the welding specification is adjusted: the welding current is 240-280A, the arc voltage is 25-32V, and the advancing speed is 370-520 mm/min.

It is noted that the welding gun can be clearly seen in the whole welding process, the welding gun is uniformly from right to left along with the formation of a molten pool in the welding process, and the downward inclination angle of the welding gun and the welding direction is 70-80 degrees. The welding wire points to the welding angle between the welding bead of the bottom layer and the horizontal plate, and oblique sawtooth welding or transverse small-swing manual welding is carried out.

Slag is cleaned in the welding process, the slag is required to be applied to successive welding layers, adjacent welding joints of each welding layer are staggered by 10mm, a crater area after welding is interrupted in each layer of welding pass is cleaned, and the sizes of welding feet of the full penetration fillet weld are consistent.

Secondly, back welding (bevel surface):

step S4, before welding, the back of the lower pier of the tank bulkhead (the back of the welding seam, which is the carbon arc gouging surface of the welding seam) is gouged by a carbon arc gouging method, the diameter of a carbon arc gouging carbon rod is 10mm, the depth of a back groove after gouging is larger than half of the thickness of a steel plate, and the shape of a narrow and deep U-shaped groove is formed as shown in figure 3.

And step S5, the angle of the U-shaped groove (the back groove carbon-planed U-shaped groove) is 45 degrees, which is shown in figure 4, so as to ensure the swinging angle of the welding gun nozzle, the length of the welding wire reaches the root of the welding seam of the carbon-planed part, the root is ensured to be melted through, the groove is trimmed after the carbon-planed U-shaped groove, and the welding can be carried out after polishing.

And step S6, removing moisture, oil rust and oxides in the range of 20mm in the U-shaped groove and the two side areas before welding.

And step S7, the downward inclination angle of the welding gun to the welding direction is 70-80 degrees, the angle of the welding gun to the bottom plate is 25-30 degrees, the welding wire should point to the included angle formed by the first layer of welding line and the workpiece bottom plate, the welding arc performs small-amplitude inclined circular ring-shaped swing by taking the welding line of the carbon planing root as the center, the carbon planing root is ensured to be thoroughly melted, and the generation of interlayer microcrack defect can be prevented.

The welding is carried out symmetrically in the even number of welding work minutes, in order to prevent welding backing cracks during construction, the speed can be properly slowed down during welding of the first layer, the thickness of the backing layer is increased, welding of the second layer is carried out immediately after the first layer is finished, and when two welders weld the same welding line, the two welders need to pay special attention to the fact that the joints are staggered by 30-50mm and do not stop on the same arc extinguishing point. As shown in fig. 5.

In order to reduce welding deformation, the welding specification should not be too large (referring to welding parameters, specifically, welding current, arc voltage and welding speed), and the welding current during priming should not exceed 240A. The interlayer temperature is controlled to be about 200 ℃ in the welding process.

The slag is cleaned in the welding process, the slag is required to be applied to successive welding layers, an arc pit area after welding is interrupted in each welding pass is cleaned, and the sizes of welding fillet feet of the full penetration fillet weld are ensured to be consistent.

The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and therefore all equivalent technical solutions should also fall within the scope of the present invention, and should be defined by the claims.