CN109530857B

CN109530857B - Thick wire single-power-supply shallow-fusion-depth efficient submerged arc automatic surfacing welding process method

Info

Publication number: CN109530857B
Application number: CN201811508801.3A
Authority: CN
Inventors: 李晓泉; 林皓; 陈一鑫; 成家林; 时振
Original assignee: Nanjing Institute of Technology
Current assignee: Nanjing Institute of Technology
Priority date: 2018-12-11
Filing date: 2018-12-11
Publication date: 2021-02-02
Anticipated expiration: 2038-12-11
Also published as: CN109530857A

Abstract

The invention discloses a thick wire single power supply shallow-melting-depth efficient submerged arc automatic surfacing welding process method, wherein 6 thin welding wires are turned into a spiral structure around 1 central welding wire by the welding wires, the prepared welding wires are sent into a welding area of a submerged arc automatic trolley through a wire guide pipe, and the welding power supply is connected to transmit welding current, so that the submerged arc automatic trolley moves along the joint of a base metal, and meanwhile, auxiliary welding agent is applied to the welding area until surfacing welding is completed. The invention utilizes the mechanical rotation action generated when each spiral monofilament is fed to drive the welding arc to rotate, and forces the liquid molten pool to perform fluid motion perpendicular to the penetration direction so as to weaken the convection motion of molten pool metal to the bottom, thereby conducting the heat in the molten pool to the width direction of a welding seam, reducing the melting amount of the root of the molten pool and expanding the welding bead along the width direction. The process method realizes the automatic submerged arc surfacing with shallow fusion depth and wide welding bead of the cable type welding wire with the diameter of 6.0mm, has extremely high surfacing efficiency and can reduce the welding cost.

Description

Thick wire single-power-supply shallow-fusion-depth efficient submerged arc automatic surfacing welding process method

Technical Field

The invention belongs to the field of submerged arc surfacing, and particularly relates to a thick wire single-power-supply shallow-penetration efficient submerged arc automatic surfacing process method.

Background

The surfacing hot spraying, physical vapor deposition, chemical vapor deposition and other surface modification methods have optimal bonding strength because the surfacing layer and the base material can realize metallurgical bonding between atoms, and are widely applied to pressure vessel manufacturing, ship manufacturing and protection, petroleum pipeline protection and the like in the industrial field. The surfacing is an economic and convenient process method for modifying the surface of a material, and is particularly suitable for large-area surface modification and repair of parts. In order to most effectively exert the function of the build-up layer, it is desirable to employ a build-up welding method that has a high deposition efficiency and a small dilution effect of the base metal on the chemical components of the build-up layer, and that exerts a modification effect on the surface of a large-area component. At present, the automatic submerged arc surfacing welding is mainly adopted in the pressure vessel and pipeline industries.

Chinese patent publication No. CN103273169A discloses a multi-wire build-up welding system and a process thereof, which perform build-up welding based on multi-wire welding, and although the welding efficiency is high, the process method has a complex requirement on equipment, requires multiple power supplies to perform independent multi-wire welding, and is not described in terms of controlling the dilution of the base material to the chemical components of the build-up welding layer. The Chinese patent with the publication number of CN105014192A discloses a welding process of heat-resistant steel cylinder band/filament surfacing stainless steel, which adopts a transition layer to carry out band or filament surfacing, and can solve the problems of chemical component dilution and welding efficiency of a surfacing layer by a base material to a certain extent, but the band surfacing also relates to the particularity of welding equipment and band materials, so that surfacing cannot be carried out by using common submerged arc welding equipment, and meanwhile, the process has no explanation on controlling the fusion depth.

The submerged arc surfacing method can achieve better surfacing layer performance, but the conventional submerged arc welding wire has some defects, mainly including larger fusion depth caused by heavy current welding, so that the melting amount of a base material to be surfaced is excessive, the dilution effect on chemical components of the surfacing layer is correspondingly larger, and the modification effect of the surfacing layer is directly reduced; when the welding current is too small, the amount of deposited metal decreases, and the weld overlay width is small. In addition, too fast a welding speed may result in a reduced weld width and even a weld that cannot be continuously formed. The diameter of a welding wire adopted by the conventional submerged arc automatic surfacing process is 4.0mm, and an effective method for improving the efficiency is to increase the diameter of the welding wire, so that the stability of the surfacing process can be ensured by increasing the welding current. However, the rated current of the submerged arc welding equipment is controlled within 1000A, and the chemical dilution effect of the base material on the overlaying layer is stronger along with the increase of the current, the formation of the welding bead is greatly influenced, and the modification effect of the overlaying layer is also seriously influenced, so that the method is not suitable for improving the efficiency in the aspect of surface overlaying modification of parts.

Disclosure of Invention

The invention aims to solve the problems of large fusion depth and narrow fusion width of single-wire submerged arc welding in the prior art, and provides a thick-wire single-power-supply shallow-fusion-depth efficient submerged arc automatic surfacing welding process method, which can use a single power supply for common submerged arc welding to carry out surfacing, achieves the welding effects of shallow fusion depth and wide welding bead, and can well meet the welding bead forming requirement.

The invention is realized by the following technical scheme:

a thick wire single power supply shallow melting depth efficient submerged arc automatic surfacing welding process method comprises the following steps:

(1) preparing a welding wire: selecting a plurality of solid welding wires with the same diameter, taking one solid welding wire as a central welding wire, and winding the rest solid welding wires around the periphery of the central welding wire in a spiral shape tightly to form a cable type thick welding wire;

(2) base metal pretreatment: polishing and derusting the parent metal, then removing oil by using an alcohol cleaning agent, and finally washing by using clear water and drying by blowing;

(3) preheating: preheating the parent metal at 90-100 ℃; the welding flux is insulated and dried for 2h at the temperature of 180 ℃ and 220 ℃;

(4) surfacing: sending the welding wire prepared in the step (1) into a welding area of the automatic submerged arc trolley through a wire guide pipe, connecting a welding power supply to transmit welding current, enabling the automatic submerged arc trolley to move along the joint of the base metal, simultaneously applying auxiliary welding flux to the welding area, and continuously controlling the interlayer temperature to be 135-plus 165 ℃ in the welding process until surfacing is completed;

(5) and (3) post-welding inspection: and performing penetration flaw detection on the welding position of the base metal after welding for 24h, and measuring the penetration depth and the penetration width of the welding position.

The process method has the unique characteristic that the multi-wire knob cable-forming type thick wire can generate rotating electric arc during welding feeding, so that the high-efficiency submerged arc surfacing welding of the thick wire with single power supply and shallow penetration is realized, and the cable-forming type welding wire is different from the dual-wire or multi-wire submerged arc surfacing welding technology of two or more independent power supplies applied at the present stage, and is characterized in that after the welding power supply is switched on, all the thin welding wires and a workpiece form multi-electric arc, and the welding wire is melted and transited to the workpiece. The special helical structure of cable type welding wire makes the electric arc thrust that every welding wire discharge produced all produce the component in the horizontal direction, and it is according to the welding wire rotation direction be left-handed or dextrorotation characteristic make electric arc carry out high-speed rotation and produce self rotation electric arc, and the power of horizontal direction can increase by a wide margin and melt wide, and in certain current range, cable type welding wire melts the homoenergetic and produces the rotation electric arc effect.

The technical scheme for further solving the problem is that the cable type rough welding wire in the step (1) is composed of 7 solid welding wires with the diameter of 2.0mm, 1 solid welding wire is taken as a central welding wire, the other 6 solid welding wires are tightly wound on the periphery of the central welding wire in a spiral shape to form peripheral wires, and the diameter of the cable type rough welding wire is 6.0 mm. The cable wire with the diameter of 6.0mm can start at the current of 300A and still can keep smaller penetration depth at the current of 600A.

The technical scheme for further solving the problem is that the solid welding wire is any one of 316L stainless steel welding wire, 309L stainless steel welding wire and nickel-based alloy welding wire.

The technical scheme for further solving the problem is that a direct current single power supply is selected as the welding power supply in the step (3), the pulse frequency of the power supply is 60-100Hz, and the welding seam cannot be well formed due to the excessively low pulse frequency; the duty ratio of the welding power supply is 50%, and the conditions of unstable welding process, poor forming and inconsistent weld penetration can be caused by too high or too low duty ratio.

The invention further solves the technical scheme that the welding process parameters in the step (3) are as follows: the welding current is 300-600A; the arc voltage is 30-31V, and the arc voltage is less than 30V, so that the deposited metal cannot be completely spread, and a hump-shaped welding seam is formed. When the arc voltage is more than 31V, the dry elongation is shortened, the melting of deposited metal is unstable, and the forming is poor; the welding speed is 30-60cm/min, when the welding speed is lower than 30cm/min, deposited metal is melted too fast, molten pig iron forward flow is generated, a welding seam is not formed well and is accompanied with the defects of surface pores and the like, and meanwhile, the welding flux is melted too much and is too thick, so that waste is caused; when the welding speed is higher than 60cm/min, the melting speed of the welding wire is lower than the welding speed, so that the fusion width is narrowed, and even the phenomenon of intermittent re-arcing occurs.

The technical scheme for further solving the problem is that the welding process parameters are matched as follows: the welding current is 300A, the arc voltage is 30V, and the surfacing speed is 30 cm/min; the welding current is 400A, the arc voltage is 30V, and the surfacing speed is 40 cm/min; the welding current is 500A, the arc voltage is 30V, and the surfacing speed is 50 cm/min; the welding current is 600A, the arc voltage is 31V, and the surfacing speed is 60cm/min

The invention further solves the technical scheme that the welding flux is SJ101 sintered welding flux.

The technical scheme for further solving the problem is that the surfacing time of the base metal pretreated in the step (2) is less than 24 hours, and the step (2) needs to be repeated when the surfacing time exceeds 24 hours.

Compared with the prior art, the invention has the advantages that:

1. the process method can achieve the purpose of realizing shallow penetration of thick wire welding. The adoption of the thick wire cable type welding wire with the thickness of 6.0mm can start the arc under the current of 300A, and still can obtain a welding bead with smaller penetration depth under the heavy current of 600A. Under the same welding parameters in a certain range, the penetration of the process method is only 1/3-1/2 of common monofilaments due to the action of the rotating arc. The method can realize the effect of diluting the chemical components of the surfacing layer by the base material, and ensure the modification effect of the surfacing layer to the maximum extent.

2. The process method can effectively increase the weld bead fusion width. Under the condition of the same current, the current density of a single strand of welding wire is about 29 percent higher than that of a common monofilament with the same specification by the process method, so that the melting speed of the cable type welding wire is higher than that of the monofilament with the same specification; meanwhile, the rotating electric arc has a horizontal thrust effect on 6 peripheral wires. The two factors make the weld penetration of the surfacing welding larger than that of the single-wire welding with the same specification.

3. The cable type rough welding wire surfacing efficiency is higher than that of a common monofilament. Under the same welding parameters, the current density of the cable type thick welding wire is high, so that the deposition efficiency is high. The deposition efficiency of the cable type welding wire can be improved by 50% compared with that of a single wire.

4. The process method has low welding cost and does not need to transform or purchase new welding equipment.

Drawings

FIG. 1 is a schematic view of the rotation and puddle flow during the cable wire welding process of the present invention.

Detailed Description

The invention will be further described with reference to the accompanying drawings and examples.

Example 1

(1) Preparing a welding wire: selecting 7 solid welding wires with the diameter of 2.0mm, taking 1 solid welding wire as a central welding wire, and tightly winding the other 6 solid welding wires around the periphery of the central welding wire in a spiral shape to form a cable type rough welding wire; the diameter of the cable type thick welding wire is 6.0mm, and the solid welding wire is a submerged arc cable type welding wire with the specification of 316L stainless steel;

(2) base metal pretreatment: polishing and derusting the parent metal, then removing oil by using an alcohol cleaning agent, and finally washing by using clear water and drying by blowing; welding within 24h of pretreatment;

(3) preheating: preheating the parent metal at 90 ℃; keeping the temperature of the flux at 200 ℃ and drying for 2 h; the welding flux is SJ101 sintered welding flux;

(4) surfacing: sending the welding wire prepared in the step (1) into a welding area of the automatic submerged arc trolley through a wire guide pipe, connecting a welding power supply to transmit welding current, selecting the welding current to be 300A, the arc voltage to be 30V, the surfacing speed to be 30cm/min, the pulse frequency of the welding power supply to be 60Hz, the duty ratio to be 50%, enabling the automatic submerged arc trolley to move along the seam of a base metal, simultaneously applying a welding agent to the welding area, and continuously controlling the interlayer temperature to be 150 ℃ in the welding process until surfacing is completed;

(5) and (3) post-welding inspection: penetration testing was performed on the welded portion of the base metal after welding for 24 hours, and the penetration depth and the penetration width measured after welding and the deposition amount converted to 1min were shown in table 1.

Example 2

(3) preheating: preheating the parent metal at 95 ℃; keeping the temperature of the flux at 180 ℃ and drying for 2 h; the welding flux is SJ101 sintered welding flux;

(4) surfacing: sending the welding wire prepared in the step (1) into a welding area of the automatic submerged arc trolley through a wire guide pipe, connecting a welding power supply to transmit welding current, selecting the welding current to be 400A, the arc voltage to be 30V, the surfacing speed to be 40cm/min, the pulse frequency of the welding power supply to be 60Hz, the duty ratio to be 50%, enabling the automatic submerged arc trolley to move along the seam of a base metal, simultaneously applying a welding agent to the welding area, and continuously controlling the interlayer temperature to be 140 ℃ in the welding process until surfacing is completed;

Example 3

Example 4

(3) preheating: preheating the parent metal at 100 ℃; keeping the temperature of the flux at 200 ℃ and drying for 2 h; the welding flux is SJ101 sintered welding flux;

(4) surfacing: sending the welding wire prepared in the step (1) into a welding area of the automatic submerged arc trolley through a wire guide pipe, connecting a welding power supply to transmit welding current, selecting the welding current to be 600A, the arc voltage to be 31V, the surfacing speed to be 60cm/min, the pulse frequency of the welding power supply to be 100Hz, the duty ratio to be 50%, enabling the automatic submerged arc trolley to move along the seam of a base metal, simultaneously applying a welding agent to the welding area, and continuously controlling the interlayer temperature to be 150 ℃ in the welding process until surfacing is completed;

Comparative example 1

The preparation method and welding process parameters are the same as those of the embodiment 1, the selection of the welding wire is different from that of the embodiment 1, and the specification of the welding wire is

A submerged arc single welding wire with the mark number of 316L. The penetration and the width of fusion measured after welding and the deposition amount converted to 1min are shown in table 1.

Comparative example 2

The preparation method and welding process parameters are the same as those of the embodiment 2, the selection of the welding wire is different from that of the embodiment 2, and the specification of the welding wire is

Comparative example 3

The preparation method and welding process parameters are the same as those of the embodiment 3, the selection of the welding wire is different from that of the embodiment 3, and the specification of the welding wire is

Comparative example 4

The preparation method and welding process parameters are the same as those of the embodiment 4, the selection of the welding wire is different from that of the embodiment 4, and the specification of the welding wire is

Table 1:

as can be seen from Table 1, the 6.0mm thick wire cable type welding wire prepared by the invention can be used for arcing under the current of 300A, a welding bead with smaller penetration depth can be obtained under the heavy current of 600A, under the same welding parameters, the penetration depth of the process method is only 1/3-1/2 of common monofilaments, and the process method can achieve the purpose of realizing shallow penetration depth in thick wire welding; under the condition of the same current, the fusion width of the cable type welding wire is larger than that of a common monofilament, so that the process method can effectively increase the fusion width of a welding bead; under the same welding parameters, the deposition amount of the cable type rough welding wire in 1min is also larger than that of a common monofilament, and the deposition efficiency of the cable type rough welding wire is improved by 50% compared with that of the monofilament, so that the surfacing efficiency of the cable type rough welding wire is higher than that of the common monofilament.

As shown in figure 1, in the welding process, mechanical rotation action generated when each spiral monofilament is fed is utilized to further drive a welding arc to rotate, a liquid molten pool is forced to perform fluid motion perpendicular to the penetration direction so as to weaken convection motion of molten pool metal to the bottom, and therefore heat inside the molten pool is conducted to the width direction of a welding seam, so that the melting amount of the root of the molten pool can be reduced, and the welding seam is expanded along the width direction. Meanwhile, the composite cable type thick wire formed by a plurality of thin welding wires can share the welding current by a plurality of welding wires, so that the current density of each single welding wire can be increased.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept of the present invention, and these changes and modifications are all within the scope of the present invention.

Claims

1. A thick wire single power supply shallow melting depth efficient submerged arc automatic surfacing welding process method is characterized in that: the method comprises the following steps:

(4) surfacing: sending the welding wire prepared in the step (1) into a welding area of the automatic submerged arc trolley through a wire guide pipe, connecting a welding power supply to transmit welding current, enabling the automatic submerged arc trolley to move along the joint of the base metal, simultaneously applying flux to the welding area, continuously controlling the interlayer temperature to be 135 plus 165 ℃ in the welding process until surfacing is completed, achieving the effects of realizing shallow penetration and increasing the weld bead fusion width by welding a thick wire,

(5) and (3) post-welding inspection: carrying out penetration flaw detection on the welding position of the base metal after welding for 24h, and measuring the penetration depth and the penetration width of the welding position; the cable type thick welding wire in the step (1) is composed of 7 solid welding wires with the diameter of 2.0mm, 1 solid welding wire is taken as a central welding wire, the rest 6 solid welding wires are tightly wound on the periphery of the central welding wire in a spiral shape to form a peripheral wire, and the diameter of the cable type thick welding wire is 6.0 mm.

2. The thick wire single power supply shallow-penetration efficient submerged arc automatic surfacing welding process method according to claim 1, which is characterized in that: the solid welding wire is any one of 316L stainless steel welding wire, 309L stainless steel welding wire and nickel-based alloy welding wire.

3. The thick wire single power supply shallow-penetration efficient submerged arc automatic surfacing welding process method according to claim 1, which is characterized in that: and (4) selecting a direct current single power supply as the welding power supply in the step (3), wherein the pulse frequency of the power supply is 60-100Hz, and the duty ratio of the welding power supply is 50%.

4. The thick wire single power supply shallow-penetration efficient submerged arc automatic surfacing welding process method according to claim 1, which is characterized in that: the welding process parameters in the step (3) are specifically as follows: the welding current is 300-600A, the arc voltage is 30-31V, and the welding speed is 30-60 cm/min.

5. The thick wire single power supply shallow-penetration efficient submerged arc automatic surfacing welding process method according to claim 4, which is characterized in that: the matching of the welding process parameters is as follows: the welding current is 300A, the arc voltage is 30V, and the surfacing speed is 30 cm/min; the welding current is 400A, the arc voltage is 30V, and the surfacing speed is 40 cm/min; the welding current is 500A, the arc voltage is 30V, and the surfacing speed is 50 cm/min; the welding current is 600A, the arc voltage is 31V, and the surfacing speed is 60 cm/min.

6. The thick wire single power supply shallow-penetration efficient submerged arc automatic surfacing welding process method according to claim 1, which is characterized in that: the flux is SJ101 sintered flux.

7. The thick wire single power supply shallow-penetration efficient submerged arc automatic surfacing welding process method according to claim 1, which is characterized in that: and (3) the surfacing time of the base metal pretreated in the step (2) is less than 24h, and the step (2) needs to be repeated when the surfacing time exceeds 24 h.