CN115464301A

CN115464301A - Flux-cored wire for laser-arc hybrid welding of high-nitrogen steel

Info

Publication number: CN115464301A
Application number: CN202211222096.7A
Authority: CN
Inventors: 殷子强; 王玉林; 沈巍; 邢振宏; 索海生; 吴昊峰; 菅荣康; 张寒; 王云鹏; 任宪康; 赵春雨
Original assignee: Shandong Senfeng Laser Equipment Co Ltd
Current assignee: Shandong Senfeng Laser Equipment Co Ltd
Priority date: 2022-10-08
Filing date: 2022-10-08
Publication date: 2022-12-13
Anticipated expiration: 2042-10-08
Also published as: CN115464301B

Abstract

The invention discloses a flux-cored wire for laser-arc hybrid welding of high-nitrogen steel, and relates to the technical field of laser-arc hybrid welding. The flux-cored wire can realize high-efficiency and high-quality welding of high-nitrogen steel, and avoids the problem that gas holes and nitrides are separated out to form brittle and hard phases due to nitrogen escape in the welding process.

Description

Flux-cored wire for laser-arc hybrid welding of high-nitrogen steel

Technical Field

The invention relates to the technical field of laser-arc hybrid welding, in particular to a flux-cored wire for laser-arc hybrid welding of high-nitrogen steel.

Background

The high-nitrogen steel as a typical resource-saving high-performance steel grade has good obdurability and corrosion resistance under the effects of interstitial solid solution of nitrogen elements and austenite stabilization. Therefore, the high nitrogen steel is increasingly one of the most potential novel engineering materials in various fields such as oil drilling, biological medical treatment, ocean engineering, space aerospace, military industry and the like, and has wide application prospect.

However, in the welding process of the high nitrogen steel, the high nitrogen steel is easy to have problems of nitrogen escape, nitride precipitation and the like under the action of a welding heat source, and the performance of a functional layer of the high nitrogen steel is reduced. How to improve the solid solution nitrogen content of the high nitrogen steel weld joint and keep the excellent comprehensive performance of the high nitrogen steel is a common problem which needs to be solved when the high nitrogen steel is widely applied in engineering practice.

The laser-arc hybrid welding integrates the high precision, high efficiency, low heat input and good bridging property of arc welding, has the coupling effect of 1+1>2, is a welding method with great potential, and becomes a research hotspot in the welding field in recent years. However, during the welding process of the high-nitrogen steel, the improvement of the energy density and the penetration capacity of a welding heat source caused by arc coupling inevitably causes the solid-solution nitrogen element in the high-nitrogen steel to escape in the form of nitrogen to form pores or to precipitate in the form of nitride to form a brittle and hard phase, thereby causing the problem of the performance reduction of a welding joint. CN 111515542A proposes a welding method of laser arc weak coupling, the invention weakens the coupling effect of laser-arc by increasing the distance between laser and arc heat source, and has a certain inhibiting effect on welding pores, but the weakening of the coupling effect of the composite heat source will lead to the reduction of welding efficiency. How to realize high-efficiency and high-quality welding of high-nitrogen steel is a bottleneck problem to be solved urgently in high-nitrogen steel engineering application.

Disclosure of Invention

The invention aims to provide a flux-cored wire for laser-arc hybrid welding of high-nitrogen steel, which aims to solve the problems in the prior art and realize high-quality and high-efficiency welding of the high-nitrogen steel.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a flux-cored wire, which consists of an outer steel sheet, an inner steel sheet, an outer flux (high nitrogen atmosphere flux core layer) and an inner flux (high nitrogen steel metallurgy flux core layer/high nitrogen steel metallurgy powder layer);

the outer steel sheet wraps the outer-layer flux core, the outer-layer flux core wraps the inner-layer steel sheet, and the inner-layer steel sheet wraps the inner-layer flux core;

the outer layer flux core comprises the following components in percentage by mass:

25-35% of aluminum ash (10-15% of aluminum and 20-30% of aluminum nitride in unit weight), 10-15% of ammonium dichromate, 10-13% of lignocellulose, 1-2% of potassium carbonate, 10-15% of iron oxide powder, 10-15% of manganese iron nitride, 8-10% of lithium fluoride, 10-20% of rutile and the balance of inevitable impurity components, wherein the impurity components comprise: less than or equal to 0.02 percent of sulfur and less than or equal to 0.025 percent of phosphorus.

The inner layer flux core comprises the following components in percentage by mass:

25-35% of iron powder, 25-30% of manganese nitride, 15-25% of chromium nitride, 7-10% of nickel powder, 15-25% of rutile, 1-2% of molybdenum powder, 0.01-0.03% of rare earth and the balance of inevitable impurity components, wherein the impurity components comprise: less than or equal to 0.02 percent of sulfur and less than or equal to 0.025 percent of phosphorus.

Furthermore, the diameter of the flux-cored wire is 1.2mm-2.8mm.

The thickness of the inner layer steel sheet and the outer layer steel sheet is 0.1-0.15mm.

Furthermore, the particle diameters of the raw materials of the outer-layer medicine core and the inner-layer medicine core are both 160-250 μm, and the loose filling fluidity is less than 18s/50g.

Further, the inner layer steel sheet and the outer layer steel sheet participate in welding metallurgical reaction; the grade of the inner layer steel sheet and the outer layer steel sheet is 08F, and the steel sheet comprises the following components in percentage by mass:

composition (I)

C

Mn

Si

S

P

Fe

Content (c) of

0.05-0.11％

0.25-0.50％

＜0.03％

＜0.035％

Allowance of

Further, the mass ratio of the outer layer medicine core to the inner layer medicine core is 10-18.

The invention further provides application of the flux-cored wire in laser-arc hybrid welding of high-nitrogen steel.

The flux-cored wire for laser-arc hybrid welding of high-nitrogen steel has a double-layer flux-cored structure, as shown in fig. 2.

The flux-cored wire is specially suitable for laser-arc hybrid welding of high-nitrogen steel. As shown in figure 3, the welding wire is fed from the rear part of the composite heat source electric arc, under the action of electric arc heat, the sheath of the flux-cored welding wire is melted, the outer layer of the flux-cored welding wire is decomposed, nitrogen-rich atmosphere is created, and the partial pressure of nitrogen element in the plasma atmosphere of the composite heat source is improved, so that the solubility of the nitrogen element in the liquid molten pool is improved. The process is as follows:

firstly, ammonium dichromate is decomposed under the action of arc heat to generate nitrogen gas and water H ₂ O：

(NH ₄ ) ₂ Cr ₂ O ₇ ＝Cr ₂ O ₃ +N ₂ ↑+4H ₂ O(180℃)；

Subsequently, the aluminum nitride in the aluminum ash reacts with the above-mentioned generated water to generate ammonia gas:

AlN+3H ₂ O＝Al(OH) ₃ +NH ₃ ↑；

under the action of arc heat, ammonia is further decomposed to generate nitrogen and hydrogen:

2NH ₃ ＝3H ₂ +N ₂ ；

the hydrogen further reacts with iron oxide:

Fe ₂ O ₃ +3H ₂ ＝2Fe+3H ₂ O；

the other main component Al in the aluminum ash can also have aluminothermic reaction with the iron oxide under the action of arc heat:

2Al+Fe ₂ O ₃ ＝＝2Fe+Al ₂ O ₃ ；

the reaction not only produces Fe, but also emits a large amount of chemical heat, so that the temperature of the molten pool is integrally improved, the existence time of the liquid molten pool is prolonged, the nitrogen element can be fully dissolved in the steel, the excessive nitrogen element can have more time to escape from the molten pool, and the formation of nitrogen holes is avoided.

Besides the function of creating nitrogen-rich atmosphere, the outer-layer flux core also carries nitrogen element to enter a molten pool to participate in metallurgical reaction, so that nitrogen in the molten pool is increased, and meanwhile, because the manganese element can improve the solubility of nitrogen in steel, the addition of the manganese iron nitride can reduce the escape tendency of the nitrogen element and prevent the formation of air holes.

Other components of the outer-layer flux core, lignocellulose and potassium carbonate mainly play an arc stabilizing role, and meanwhile, the lignocellulose is heated to generate carbon dioxide gas, so that the protection effect on a molten pool is enhanced; the rutile plays roles of slagging and arc stabilization, so that a welding pool is solidified under the condition of slag-gas combined protection, and the welding quality is more stable. The lithium fluoride is mainly used for stabilizing the arc and improving the fluidity of the molten pool, and under the stirring action of the laser-arc composite heat source, the dissolving speed of nitrogen element in the liquid molten pool is accelerated, and the micro segregation of nitrogen is prevented.

Because of the protection of the metal skin and the outer layer flux core, the inner layer flux core powder can be sent into a region with higher temperature and close to the center of a laser arc composite heat source, the inner layer flux core powder mainly takes iron powder, manganese nitride and chromium nitride as raw materials to construct a Fe-Cr-Mn-N high-nitrogen steel component system, and the solubility of nitrogen element in the alloy system is highest.

FIG. 4 shows the effect of the Cr and Mn contents in the Fe-Cr-Mn-N alloy system at 837K and 0.1MPa on the solubility of nitrogen, and it can be seen that the solubility of nitrogen in the 20-Cr-20-Mn alloy system can reach 0.8% or more.

The molybdenum element and the rare earth can improve the solubility of nitrogen in a liquid molten pool and have the function of refining grains, on one hand, more nitrogen elements are dissolved in the liquid molten pool, and on the other hand, the function of refining grains is achieved in the solidification stage of the molten pool. The nickel element is mainly used for preventing the brittle hardening of materials caused by the over-high solidification speed of a laser-electric arc composite welding pool, enhancing the toughness of weld metal and improving the comprehensive mechanical property of a weld.

The flux-cored wire of the invention is not only free from weakening the coupling effect of laser and electric arc, but also can improve the wire feeding speed of the welding wire and improve the welding production efficiency because the welding wire generates aluminum thermal reaction under the action of the electric arc and releases a large amount of heat.

When the flux-cored wire is used for welding, the welding process parameters are as follows: laser power is 4-8KW, TIG arc current is 200-240A, voltage is 20-25V, tungsten electrode-laser distance is 1-3mm, and welding speed is 400-600mm/min.

The invention discloses the following technical effects:

the flux-cored wire can realize high-efficiency and high-quality welding of high-nitrogen steel, and avoids the problem that gas holes and nitrides are separated out to form brittle and hard phases due to nitrogen escape in the welding process.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a view showing a structure of bending and rolling a 08F steel strip according to example 1 of the present invention, (a) is a bent U-shape, and (b) is a rolled groove shape;

FIG. 2 is a schematic structural diagram of a flux-cored wire for laser-arc hybrid welding of high-nitrogen steel according to the present invention;

FIG. 3 is a schematic diagram of laser-arc hybrid welding of high-nitrogen steel using the flux-cored wire of the present invention;

FIG. 4 is a graph of the effect of Cr and Mn content on nitrogen solubility in a Fe-Cr-Mn-N alloy system at 837K, 0.1 MPa;

FIG. 5 shows the real-time acquisition results of the voltage and current of arc welding in the welding process of example 1;

FIG. 6 is a weld forming diagram obtained by welding in example 1;

FIG. 7 is a slag removal map of a weld obtained by welding in example 1;

FIG. 8 shows the real-time measurement results of arc welding voltage and current in the welding process of example 2;

FIG. 9 is a weld forming diagram obtained by welding in example 2;

FIG. 10 is a slag removal map of a weld obtained by welding in example 2;

FIG. 11 is a macro-topographical view of a weld joint obtained by welding in example 3;

FIG. 12 is an SEM image of a cross-section of a weld seam obtained by welding in example 3;

FIG. 13 shows the real-time acquisition results of the arc welding voltage and current in the welding process of example 3.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but rather as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the documents are cited. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

Example 1

The flux-cored wire in the embodiment has a double-layer flux-cored structure as shown in fig. 2, and the diameter of the flux-cored wire is 2.0mm;

when the powder is prepared, the 08F steel belt is bent into a U shape as shown in figure 1 (a), the outer-layer flux core powder is filled, and the powder is uniformly spread on the steel belt through a vibration mechanism. Further rolling closes the open end of the strip and forms a groove shape as shown in fig. 1 (b). After the inner layer flux-cored powder is filled, the inner layer flux-cored powder is further rolled, so that the opening end of the inner layer flux-cored powder is closed, and the flux-cored wire (the thickness of a steel sheet is 0.1 mm) with the section shown in figure 2 is formed.

In the embodiment, the grade of the inner layer steel sheet and the outer layer steel sheet is 08F, and the components are calculated according to the mass percentage as follows:

composition (I)

C

Mn

Si

S

P

Fe

Content (c) of

0.06％

0.3％

＜0.03％

＜0.035％

Allowance of

In this embodiment, the outer layer flux core comprises the following components in percentage by mass:

26% of aluminum ash (the aluminum ash in unit weight contains 10% of aluminum and 20% of aluminum nitride), 12% of ammonium dichromate, 11% of lignocellulose, 2% of potassium carbonate, 15% of iron oxide powder, 15% of manganese iron nitride, 8% of lithium fluoride and 11% of rutile, and the balance of inevitable impurity components, wherein the impurity components comprise: less than or equal to 0.02 percent of sulfur and less than or equal to 0.025 percent of phosphorus.

In this embodiment, the inner core comprises the following components in percentage by mass:

25% of iron powder, 26% of manganese nitride, 20% of chromium nitride, 8% of nickel powder, 20% of rutile, 1% of molybdenum powder, 0.01% of rare earth and the balance of inevitable impurity components, wherein the impurity components comprise: less than or equal to 0.02 percent of sulfur and less than or equal to 0.025 percent of phosphorus.

The mass ratio of the inner layer core to the outer layer core is 10/18;

the grain diameter of the powder of the inner-layer medicine core and the outer-layer medicine core is 160-250 mu m, and the loose filling fluidity is less than 18s/50g after mixing.

The flux-cored welding wire is used for welding high-nitrogen steel, and the welding process parameters are as follows: the laser power is 6KW, TIG arc current 210A, the voltage is 20V, the distance between a tungsten electrode and laser is 2mm, the welding speed is 400mm/min, and a surfacing test is carried out on 304L base metal, so that the welding current and the voltage are very stable, are approximately linear and are typical spray transition waveforms.

The real-time acquisition result of the voltage and the current of the electric arc welding is shown in figure 5, the stability of the welding process can be visually judged through the voltage and the waveform of the current, and the stability of the welding process can be seen from the figure; the obtained weld joint is formed as shown in FIG. 6, and it can be seen from the figure that the weld joint skull protection is good; after the welding seam is deslagged, as shown in figure 7, most of slag shells are separated from metal after falling ball impact, the metal luster is exposed on the welding seam, and the slag detachability of the welding seam slag is good.

The detection shows that the nitrogen content of the cladding layer is 0.45 percent, and the standard that the nitrogen content of the high-nitrogen steel is more than 0.4 percent is met.

Example 2

a flux-cored wire (steel sheet thickness 0.15 mm) was produced in the same manner as in example 1.

In the embodiment, the grade of the inner layer steel sheet and the outer layer steel sheet is 08F, and the steel sheet comprises the following components in percentage by mass:

composition (I)

C

Mn

Si

S

P

Fe

Content (wt.)

0.06％

0.3％

＜0.03％

＜0.035％

Balance of

30% of aluminum ash (the aluminum ash in unit weight contains 10% of aluminum and 20% of aluminum nitride), 12% of ammonium dichromate, 12% of lignocellulose, 1% of potassium carbonate, 13% of iron oxide powder, 11% of ferromanganese nitride, 8% of lithium fluoride and 13% of rutile, and the balance of inevitable impurity components, wherein the impurity components comprise: less than or equal to 0.02 percent of sulfur and less than or equal to 0.025 percent of phosphorus.

30% of iron powder, 25% of manganese nitride, 15% of chromium nitride, 8.5% of nickel powder, 20% of rutile, 1.5% of molybdenum powder, 0.03% of rare earth and the balance of inevitable impurity components, wherein the impurity components comprise: less than or equal to 0.02 percent of sulfur and less than or equal to 0.025 percent of phosphorus.

The mass ratio of the inner layer drug core to the outer layer drug core is 10/20;

The flux-cored welding wire is used for welding high-nitrogen steel, and the welding process parameters are as follows: the laser power is 6KW, TIG arc current is 220A, the voltage is 20V, the distance between a tungsten electrode and laser is 3mm, the welding speed is 400mm/min, a surfacing test is carried out on 304L base metal, it can be seen that the molten drop transition form is spray transition, and the stability of the welding process is better according to the current and voltage waveforms.

The real-time acquisition result of the voltage and the current of the electric arc welding is shown in figure 8, the stability of the welding process can be visually judged through the voltage and the waveform of the current, and the stability of the welding process can be seen from the figure; the obtained weld is formed as shown in fig. 9, and the weld skull protection is good as can be seen from the figure; as shown in figure 10 after the slag is removed from the welding seam, most of slag shells are separated from the metal after the falling ball impact, the metal luster is exposed on the welding seam, and the slag removal performance of the welding seam slag is good.

Example 3

The flux-cored wire in the embodiment has a double-layer flux-cored structure as shown in fig. 2, and the diameter of the flux-cored wire is 1.6mm;

composition (A)

C

Mn

Si

S

P

Fe

Content (wt.)

0.061％

0.3％

＜0.03％

＜0.035％

Balance of

35% of aluminum ash (containing 15% of aluminum and 30% of aluminum nitride in unit weight), 15% of ammonium dichromate, 10% of lignocellulose, 2% of potassium carbonate, 13% of iron oxide powder, 13% of manganese iron nitride, 9% of lithium fluoride and 12% of rutile, and the balance of inevitable impurity components, wherein the impurity components comprise: less than or equal to 0.02 percent of sulfur and less than or equal to 0.025 percent of phosphorus.

20% of iron powder, 28% of manganese nitride, 20% of chromium nitride, 9% of nickel powder, 18% of rutile, 1.5% of molybdenum powder, 0.02% of rare earth and the balance of unavoidable impurity components, wherein the impurity components comprise: less than or equal to 0.02 percent of sulfur and less than or equal to 0.025 percent of phosphorus.

The mass ratio of the inner layer drug core to the outer layer drug core is 10/22;

The flux-cored welding wire is used for welding high-nitrogen steel, and the welding process parameters are as follows: the laser power is 4KW, TIG arc current is 160A, voltage is 20V, the distance between a tungsten electrode and laser is 3mm, the welding speed is 400mm/min, a surfacing welding test is carried out on 304L base metal, and the fusion drop transition form is short-circuit transition and has better stability in the welding process through the collected electrical parameter curve.

The macroscopic morphology of the weld is obtained as shown in fig. 11, and the weld is well formed. The gold phase is prepared on the section of the welding seam and is analyzed by SEM (figure 12), and it can be seen that although the structure coarsening phenomenon of the gold phase appears in each area of the welding seam, no air holes exist in the welding seam, slag inclusion and other defects exist.

FIG. 13 shows the real-time measurement results of arc welding voltage and current in the welding process of example 3.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. The flux-cored wire is characterized by consisting of an outer steel sheet, an inner steel sheet, an outer flux core and an inner flux core;

the outer steel sheet wraps the outer flux core, the outer flux core wraps the inner steel sheet, and the inner steel sheet wraps the inner flux core;

25-35% of aluminum ash, 10-15% of ammonium dichromate, 10-13% of lignocellulose, 1-2% of potassium carbonate, 10-15% of iron oxide powder, 10-15% of ferromanganese nitride, 8-10% of lithium fluoride, 10-20% of rutile and the balance of inevitable impurity components, wherein the impurity components comprise: sulfur is less than or equal to 0.02 percent, and phosphorus is less than or equal to 0.025 percent;

2. The flux-cored welding wire of claim 1, wherein the diameter of the flux-cored welding wire is 1.2mm to 2.8mm.

3. The flux-cored wire of claim 1, wherein the outer core and the inner core each have a raw material particle size of 160 μm to 250 μm and a loose flow of less than 18s/50g.

4. The flux-cored wire of claim 1, wherein the inner layer steel sheet and the outer layer steel sheet comprise the following components in percentage by mass:

composition (A) C Mn Si S P Fe Content (wt.) 0.05-0.11％ 0.25-0.50％＜0.03％＜0.035％＜0.035％ Balance of

。

5. The flux-cored welding wire of claim 1, wherein the mass ratio of the outer layer core to the inner layer core is 10:18 to 22.

6. Use of the flux-cored wire of any one of claims 1 to 5 for laser arc hybrid welding of high nitrogen steels.