阅读说明：本技术 一种有效控制热裂的镍铬基焊丝及方法与坡口形式 (Nickel-chromium-based welding wire capable of effectively controlling thermal cracking, method and groove form ) 是由 褚巧玲 张�林 夏拓 张敏 赵鹏康 李继红 王锵 于 2021-08-23 设计创作，主要内容包括：本发明公开的一种有效控制热裂的镍铬基焊丝,包括药芯和焊皮,其中药芯按质量百分比由以下组分组成：Cr粉40.0～60.0％,Nb粉20.0～30.0％,Mo粉20.0～30.0％,以上组分质量百分比之和为100％。该有效控制热裂的镍铬基焊丝,专门用于铜-钢爆炸复合板对接焊接过程中过渡层的焊接,可有效解决铜-钢复合板焊接过程中焊缝开裂的问题。还提供该种有效控制热裂的镍铬基焊丝的制备方法与坡口形式。(The invention discloses a nickel-chromium-based welding wire capable of effectively controlling hot cracking, which comprises a flux core and a welding skin, wherein the flux core comprises the following components in percentage by mass: 40.0-60.0% of Cr powder, 20.0-30.0% of Nb powder and 20.0-30.0% of Mo powder, wherein the sum of the mass percentages of the components is 100%. The nickel-chromium-based welding wire capable of effectively controlling heat cracking is specially used for welding a transition layer in the butt welding process of a copper-steel explosive composite plate, and can effectively solve the problem of weld cracking in the welding process of the copper-steel composite plate. Also provides a preparation method and a groove form of the nickel-chromium-based welding wire for effectively controlling hot cracking.)

1. The nickel-chromium-based welding wire capable of effectively controlling hot cracking is characterized by comprising a flux core and a welding skin, wherein the flux core comprises the following components in percentage by mass: 40.0-60.0% of Cr powder, 20.0-30.0% of Nb powder and 20.0-30.0% of Mo powder, wherein the sum of the mass percentages of the components is 100%.

2. The nickel-chromium-based welding wire capable of effectively controlling heat cracking as claimed in claim 1, wherein the granularity of each powder is 100-200 meshes.

3. The nickel-chromium-based welding wire capable of effectively controlling heat cracking as claimed in claim 1, wherein the welding skin is a pure nickel strip, the thickness of the nickel strip is 0.4mm, and the width of the nickel strip is 7 mm.

4. A preparation method of a nickel-chromium-based welding wire capable of effectively controlling heat cracking is characterized by comprising the following specific steps:

step 1: weighing the following medicinal powder in percentage by mass: 40.0-60.0% of Cr powder, 20.0-30.0% of Nb powder and 20.0-30.0% of Mo powder, wherein the sum of the mass percentages of the components is 100%;

step 2: heating the medicinal powder weighed in the step 1 in a vacuum heating furnace at 220-320 ℃ for 2.5-3.5h, and removing crystal water in the medicinal powder; putting the dried medicinal powder into a powder mixer for fully mixing for 3.5-5 h;

and step 3: a pure nickel strip is used as a welding skin, oil on the surface of the pure nickel strip is removed by alcohol, the powder prepared in the step 2 is wrapped in the pure nickel strip by flux-cored wire drawing equipment, and the aperture of a first drawing die is 2.6 mm;

and 4, step 4: after the first process is finished, the aperture of the die is reduced in sequence, and finally the flux-cored wire with the diameter of 1.0-1.2 mm is obtained;

and 5: and after the flux-cored wire is drawn, the flux-cored wire is wound on a wire reel through a wire winding machine and finally sealed in a flux-cored wire vacuum packaging bag for later use.

5. The method for preparing the nickel-chromium-based welding wire capable of effectively controlling the heat cracking as claimed in claim 4, wherein in the step 1, the granularity of each powder is 100-200 meshes.

6. The method for preparing the nickel-chromium-based welding wire capable of effectively controlling the heat crack according to the claim 4, wherein in the step 3, the thickness of the nickel belt is 0.4mm, and the width of the nickel belt is 7 mm; the filling rate of the flux-cored wire is controlled to be 25-30 wt.%.

7. The groove form for welding the copper-steel composite plate by adopting the nickel-chromium-based welding wire capable of effectively controlling the heat cracking as claimed in any one of claims 1 to 3, wherein the two sides of the copper-steel composite plate are respectively provided with an asymmetric V-shaped groove, wherein the angle of the copper side groove is 90 degrees, the angle of the steel side groove is 50 degrees, the distance from the bottom of the copper side groove to the interface of the copper-steel composite plate is 1-3mm, and 2 layers of welding seams are welded for reducing the dilution rate during the welding of the transition layer.

Technical Field

The invention belongs to the field of metal materials, and particularly relates to a nickel-chromium-based welding wire capable of effectively controlling heat cracking, a preparation method of the nickel-chromium-based welding wire capable of effectively controlling heat cracking and a groove form.

Background

With the development of science and technology and the deepening of economic globalization, the market has more and more severe requirements on the performance of materials and the use environment. In some special fields, the comprehensive performance of traditional single materials is difficult to meet the requirement of actual production, and metal materials with different chemical properties and physical properties are often connected together to utilize the performance and economic complementation between different materials, and the connection between copper and steel by dissimilar metals is one of the materials. The copper-steel composite structure has the advantages of good electrical conductivity and thermal conductivity of copper, good welding stability of steel materials, low price and the like, the excellent performances of the copper and the steel materials are perfectly combined, the respective defects are effectively avoided, and the economic benefit is maximized.

The copper-steel composite plate inevitably encounters the butt joint problem during the use process. Although copper and steel do not form brittle intermetallic compounds, the difference between the two is large in thermophysical properties, and thus thermal cracking is likely to occur at the time of interfacial bonding. Through systematic studies, it was found that the thermal cracking is mainly caused by the large difference in melting points between copper and steel. When the copper element content in the molten pool is low and the steel content is high, the low-melting-point steel is solidified first, and then the low-melting-point copper is still in a liquid phase and distributed at the interface of the solidified steel crystal grains, so that cracking is caused under the action of welding thermal stress. Therefore, in order to overcome the cracking problem during the welding of the copper-steel composite plate, a proper transition layer material needs to be selected to ensure that the copper-steel composite plate can realize high-quality connection with copper and steel; in addition, the groove form of the butt joint of the composite plate, particularly the position and the size of the welding seam of the transition layer, needs to be considered, so that the proportion and the mixing condition of the alloy elements in the molten pool can be effectively controlled.

Disclosure of Invention

The invention aims to provide a nickel-chromium-based welding wire capable of effectively controlling heat cracking, which is specially used for welding a transition layer in the butt welding process of a copper-steel explosive composite plate and can effectively solve the problem of weld cracking in the welding process of the copper-steel composite plate.

The second purpose of the invention is to provide a preparation method of the nickel-chromium-based welding wire capable of effectively controlling heat cracking.

The third purpose of the invention is to provide a groove form when the nickel-chromium-based welding wire for effectively controlling hot cracking is used for welding the copper-steel composite plate.

The first technical scheme adopted by the invention is that the nickel-chromium-based welding wire capable of effectively controlling hot cracking comprises a flux core and a welding skin, wherein the flux core comprises the following components in percentage by mass: 40.0-60.0% of Cr powder, 20.0-30.0% of Nb powder and 20.0-30.0% of Mo powder, wherein the sum of the mass percentages of the components is 100%.

The present invention is also characterized in that,

the granularity of each medicinal powder is 100-200 meshes.

The welding skin is a pure nickel strap, the thickness of the nickel strap is 0.4mm, and the width of the nickel strap is 7 mm.

The second technical scheme adopted by the invention is that the preparation method of the nickel-chromium-based welding wire capable of effectively controlling hot cracking comprises the following specific steps:

step 1: weighing the following medicinal powder in percentage by mass: 40.0-60.0% of Cr powder, 20.0-30.0% of Nb powder and 20.0-30.0% of Mo powder, wherein the sum of the mass percentages of the components is 100%;

step 2: heating the medicinal powder weighed in the step 1 in a vacuum heating furnace at 220-320 ℃ for 2.5-3.5h, and removing crystal water in the medicinal powder; putting the dried medicinal powder into a powder mixer for fully mixing for 3.5-5 h;

and step 3: a pure nickel strip is used as a welding skin, oil on the surface of the pure nickel strip is removed by alcohol, the powder prepared in the step 2 is wrapped in the pure nickel strip by flux-cored wire drawing equipment, and the aperture of a first drawing die is 2.6 mm;

and 4, step 4: after the first process is finished, the aperture of the die is reduced in sequence, and finally the flux-cored wire with the diameter of 1.0-1.2 mm is obtained;

and 5: and after the flux-cored wire is drawn, the flux-cored wire is wound on a wire reel through a wire winding machine and finally sealed in a flux-cored wire vacuum packaging bag for later use.

The present invention is also characterized in that,

in the step 1, the granularity of each medicinal powder is 100-200 meshes.

In the step 3, the thickness of the nickel strap is 0.4mm, and the width of the nickel strap is 7 mm; the filling rate of the flux-cored wire is controlled to be 25-30 wt.%.

According to the third technical scheme, when the nickel-chromium-based welding wire capable of effectively controlling hot cracking is used for welding the copper-steel composite plate, the two sides of the copper-steel composite plate are respectively provided with asymmetric V-shaped grooves, wherein the angle of the copper side groove is 90 degrees, the angle of the steel side groove is 50 degrees, the distance between the bottom of the copper side groove and the interface of the copper-steel composite plate is 1-3mm, and when the transition layer is welded, 2 layers of welding seams are welded for reducing the dilution rate.

The invention has the beneficial effects that:

(1) the welding wire is suitable for welding the transition layer of the copper-steel composite plate, and can effectively solve the problem of weld cracking in the welding process of the copper-steel composite plate.

(2) The nickel-chromium-based welding wire has the advantages that the main elements of nickel and the base metal copper can be infinitely dissolved, the solid solubility between the nickel and the base metal steel is high, and the brittle intermetallic compound is not generated. Therefore, the nickel-chromium-based welding wire can realize metallurgical connection of a copper side welding seam and a steel welding seam. In addition, the invention has requirements on the groove form and the bottom of the transition layer and the copper-steel interface (the distance between the bottom of the copper side groove and the copper-steel composite plate interface is 2mm), and can effectively solve the problem that copper element permeates into steel weld grains to cause cracking during the welding of the transition layer. The invention designs 2 layers of welding seams for the transition layer, which can effectively reduce the dilution rate, thereby controlling the content of Fe element in the molten pool.

(3) The components of the nickel-chromium-based welding wire for the transition layer of the copper-steel composite plate can be flexibly adjusted through the powder proportion; compared with a solid welding wire, the flux-cored welding wire has higher cladding efficiency.

(4) The groove form designed by the invention has lower operation requirements on welding workers, thereby improving the production efficiency.

Drawings

FIG. 1 is a groove form of a copper-steel composite plate when the welding wire of the present invention is used for welding the copper-steel composite plate;

FIG. 2 is a sequence of welding copper-steel composite panels using the welding wire of the present invention during welding of copper-steel composite panels;

fig. 3 is a macroscopic structure morphology diagram of a transition layer welding seam, a bottom steel matrix and an upper copper welding seam when the flux-cored wire prepared in embodiment 2 is welded on a copper-steel composite plate transition layer.

Fig. 4 is a high-power structure morphology diagram of a transition layer welding seam when the flux-cored wire prepared in the embodiment 2 is welded on a copper-steel composite plate transition layer.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention provides a nickel-chromium-based welding wire capable of effectively controlling hot cracking, which comprises a flux core and a welding skin, wherein the flux core comprises the following components in percentage by mass: 40.0-60.0% of Cr powder, 20.0-30.0% of Nb powder and 20.0-30.0% of Mo powder, wherein the sum of the mass percentages of the components is 100%.

The granularity of each medicinal powder is 100-200 meshes; the welding skin is a pure nickel strap, the thickness of the nickel strap is 0.4mm, and the width of the nickel strap is 7 mm.

The main alloy components in the flux-cored wire have the following functions and functions:

the Ni element is the main alloy element of the flux-cored wire, can improve the strength of the welding line and enables the welding line to have good plasticity and toughness. The weldability of Ni and Fe and Ni and Cu is good, so that the welding seam of the transition layer mainly takes Ni as the main part and can effectively play a role of connecting Cu and Fe.

The Cr element is used as a main alloy element of the flux-cored wire powder, can reduce the formation of a gamma phase in a welding line and stabilize an alpha phase. When the content of Cr element in the welding seam reaches a certain content, Cr is generated on the surface of the welding seam₂O₃And the protective layer plays roles of oxidation resistance and corrosion resistance.

The Nb element is used as a main alloy element of the flux-cored wire powder, the weldability between Nb and Ni is good, and the bonding strength between a transition layer welding seam and a bottom steel matrix can be improved. No brittle intermetallic compounds are formed between Nb and Cu.

Mo is used as a main alloy element of the flux-cored wire powder, the Mo and the Cr can be infinitely dissolved in solid, and the Mo mainly plays a solid solution strengthening role in a Ni-rich matrix, so that the strength of a welding seam is improved.

When the flux-cored wire is used for welding the transition layer, the transition layer is divided into 2 layers for welding seams, and lower heat input is adopted, so that the flux-cored wire has the following functions and functions: the flux-cored wire mainly comprises Ni elements, and when the flux-cored wire is subjected to first layer welding, Ni elements and Fe elements exist in a welding seam of a transition layer at the same time, wherein the content of the Fe elements is lower than that of the Ni elements; when the second layer welding is carried out, Cu, Ni and Fe elements exist in the welding seam of the transition layer at the same time, and the Fe element in the welding seam of the second layer transition layer is less than that in the first layer. In this case, the Cu element content and the Ni element content in the second-layer transition layer weld are high, and only a small amount of Fe is present. Because the melting point of Fe is higher, the nucleation is preferential, and even if solidification shrinkage exists, a large amount of Cu liquid phase in a surrounding molten pool can be supplemented in time, so that the generation of solidification cracks is fundamentally inhibited.

The invention also provides a preparation method of the nickel-chromium-based welding wire for effectively controlling hot cracking, which comprises the following specific steps:

step 1: weighing the following medicinal powder in percentage by mass: 40.0-60.0% of Cr powder, 20.0-30.0% of Nb powder and 20.0-30.0% of Mo powder, wherein the sum of the mass percentages of the components is 100%;

in the step 1, the purity of Cr powder is more than or equal to 99.9 percent, the purity of Nb powder is more than or equal to 99.9 percent, the purity of Mo powder is more than or equal to 99.9 percent, and the granularity of each powder is 100-200 meshes;

step 2: heating the medicinal powder weighed in the step 1 in a vacuum heating furnace at 220-320 ℃ for 2.5-3.5h, and removing crystal water in the medicinal powder; putting the dried medicinal powder into a powder mixer for fully mixing for 3.5-5 h;

and step 3: a pure nickel strip is used as a welding skin, oil on the surface of the pure nickel strip is removed by alcohol, the powder prepared in the step 2 is wrapped in the pure nickel strip by flux-cored wire drawing equipment, and the aperture of a first drawing die is 2.6 mm; in the step 3, the thickness of the nickel strap is 0.4mm, and the width of the nickel strap is 7 mm; the filling rate of the flux-cored wire is controlled to be 25-30 wt.%.

And 4, step 4: after the first process is finished, the aperture of the die is reduced in sequence, and finally the flux-cored wire with the diameter of 1.0-1.2 mm is obtained;

and 5: and after the flux-cored wire is drawn, the flux-cored wire is wound on a wire reel through a wire winding machine and finally sealed in a flux-cored wire vacuum packaging bag for later use.

The invention also provides a bevel form when the nickel-chromium-based welding wire for effectively controlling hot cracking is adopted to weld the copper-steel composite plate, wherein two sides of the copper-steel composite plate are respectively provided with an asymmetric V-shaped bevel, the angle of the copper side bevel is 90 degrees, the angle of the steel side bevel is 50 degrees, the bottom of the copper side bevel is 1-3mm away from the interface of the copper-steel composite plate, and 2 layers of welding seams are welded by adopting lower heat input in order to reduce the dilution rate during the welding of the transition layer.

Example 1

Step 1: weighing the following medicinal powder in percentage by mass: 40.0 percent of Cr powder, 30 percent of Nb powder and 30.0 percent of Mo powder, wherein the sum of the mass percentages of the components is 100 percent; the granularity of each medicinal powder is 100 meshes;

step 2: heating the powder weighed in the step 1 in a vacuum heating furnace at the heating temperature of 300 ℃ for 2.5 hours, and removing crystal water in the powder; putting the dried medicinal powder into a powder mixing machine for fully mixing for 3.5 h;

and step 3: a pure nickel strip is used as a welding skin, oil on the surface of the pure nickel strip is removed by alcohol, the powder prepared in the step 2 is wrapped in the pure nickel strip by flux-cored wire drawing equipment, and the aperture of a first drawing die is 2.6 mm; in the step 3, the thickness of the nickel strap is 0.4mm, and the width of the nickel strap is 7 mm; the filling rate of the flux-cored wire is controlled at 25 wt.%.

And 4, step 4: after the first process is finished, the aperture of the die is reduced in sequence, and finally the flux-cored wire with the diameter of 1.0mm is obtained.

And 5: and after the flux-cored wire is drawn, the flux-cored wire is wound on a wire reel through a wire winding machine and finally sealed in a flux-cored wire vacuum packaging bag for later use.

The nickel-chromium-based welding wire prepared in the embodiment 1 is used for welding a copper-steel composite plate, wherein two sides of the composite plate are respectively provided with an asymmetric V-shaped groove, the angle of the copper side groove is 90 degrees, the angle of the steel side groove is 50 degrees, the bottom of the copper side groove is 2mm away from the interface of the copper-steel composite plate, and 2 layers of welding seams are adopted for welding a transition layer. The groove size is shown in fig. 1. The composite plate welding sequence is shown in fig. 2: firstly, welding a steel layer, wherein the welding material is an ER50-6 welding wire (the diameter is 1.2mm), and the welding current is 150-160A; then, welding a transition layer, adopting the flux-cored wire of the invention, welding current is 100-120A, and welding 2 layers of welding seams; and finally, welding the copper side, wherein the welding material is ERCuSi-Al (the diameter is 1.2mm), and the welding current is 200-250A.

Through tests, the tensile strength of the welding joint of the copper-steel composite plate is 344MPa, and the elongation is 12%.

Example 2

Step 1: weighing the following medicinal powder in percentage by mass: 50.0 percent of Cr powder, 25.0 percent of Nb powder and 25.0 percent of Mo powder, wherein the sum of the mass percentages of the components is 100 percent; the granularity of each medicinal powder is 200 meshes;

step 2: heating the medicinal powder weighed in the step 1 in a vacuum heating furnace at 250 ℃ for 2.5 hours, and removing crystal water in the medicinal powder; putting the dried medicinal powder into a powder mixing machine for fully mixing for 3.5 h;

and step 3: a pure nickel strip is used as a welding skin, oil on the surface of the pure nickel strip is removed by alcohol, the powder prepared in the step 2 is wrapped in the pure nickel strip by flux-cored wire drawing equipment, and the aperture of a first drawing die is 2.6 mm; in the step 3, the thickness of the nickel strap is 0.4mm, and the width of the nickel strap is 7 mm; the filling rate of the flux-cored wire is controlled at 28 wt.%.

And 4, step 4: after the first process is finished, the aperture of the die is reduced in sequence, and finally the flux-cored wire with the diameter of 1.2mm is obtained.

And 5: and after the flux-cored wire is drawn, the flux-cored wire is wound on a wire reel through a wire winding machine and finally sealed in a flux-cored wire vacuum packaging bag for later use.

The nickel-chromium-based welding wire prepared in the embodiment 2 is used for welding the copper-steel composite plate, wherein two sides of the composite plate are respectively provided with asymmetric V-shaped grooves, the angle of the copper side groove is 90 degrees, the angle of the steel side groove is 50 degrees, the bottom of the copper side groove is 2mm away from the interface of the copper-steel composite plate, and 2 layers of welding seams are adopted for welding the transition layer. The groove size is shown in fig. 1. The composite plate welding sequence is shown in fig. 2: firstly, welding a steel layer, wherein the welding material is an ER50-6 welding wire (the diameter is 1.2mm), and the welding current is 150-160A; then, welding a transition layer, adopting the flux-cored wire of the invention, welding current is 100-120A, and welding 2 layers of welding seams; and finally, welding the copper side, wherein the welding material is ERCuSi-Al (the diameter is 1.2mm), and the welding current is 200-250A.

The test shows that the tensile strength of the welding joint of the copper-steel composite plate is 382MPa, and the elongation is 17%.

The nickel-chromium-based welding wire prepared in example 2 is welded with a copper-steel composite plate transition layer. The interface of the transition layer weld joint and the steel weld joint is shown in fig. 3, the transition layer weld joint and the steel weld joint are well combined, and no defects such as cracks, air holes and the like are found. The microstructure of the weld of the transition layer is shown in FIG. 4, and is mainly austenite, and the morphology of the weld is cellular dendrite.

Example 3

Step 1: weighing the following medicinal powder in percentage by mass: 60.0 percent of Cr powder, 20.0 percent of Nb powder and 20.0 percent of Mo powder, wherein the sum of the mass percentages of the components is 100 percent; the granularity of each medicinal powder is 200 meshes;

step 2: heating the powder weighed in the step 1 in a vacuum heating furnace at 220 ℃ for 3.5 hours, and removing crystal water in the powder; putting the dried medicinal powder into a powder mixing machine for fully mixing for 5 h;

and step 3: a pure nickel strip is used as a welding skin, oil on the surface of the pure nickel strip is removed by alcohol, the powder prepared in the step 2 is wrapped in the pure nickel strip by flux-cored wire drawing equipment, and the aperture of a first drawing die is 2.6 mm; in the step 3, the thickness of the nickel strap is 0.4mm, and the width of the nickel strap is 7 mm; the filling rate of the flux-cored wire is controlled at 30 wt.%.

And 4, step 4: after the first process is finished, the aperture of the die is reduced in sequence, and finally the flux-cored wire with the diameter of 1.0mm is obtained.

And 5: and after the flux-cored wire is drawn, the flux-cored wire is wound on a wire reel through a wire winding machine and finally sealed in a flux-cored wire vacuum packaging bag for later use.

The nickel-chromium-based welding wire prepared in the embodiment 3 is used for welding the copper-steel composite plate, wherein two sides of the composite plate are respectively provided with asymmetric V-shaped grooves, the angle of the copper side groove is 90 degrees, the angle of the steel side groove is 50 degrees, the distance from the bottom of the copper side groove to the interface of the copper-steel composite plate is 2mm, and 2 layers of welding seams are adopted for welding the transition layer. The groove size is shown in fig. 1. The composite plate welding sequence is shown in fig. 2: firstly, welding a steel layer, wherein the welding material is an ER50-6 welding wire (the diameter is 1.2mm), and the welding current is 150-160A; then, welding a transition layer, adopting the flux-cored wire of the invention, welding current is 100-120A, and welding 2 layers of welding seams; and finally, welding the copper side, wherein the welding material is ERCuSi-Al (the diameter is 1.2mm), and the welding current is 200-250A.

The test shows that the tensile strength of the welding joint of the copper-steel composite plate is 395MPa, and the elongation is 15%.

Example 4

Step 1: weighing the following medicinal powder in percentage by mass: 55.0 percent of Cr powder, 25.0 percent of Nb powder and 20.0 percent of Mo powder, wherein the sum of the mass percentages of the components is 100 percent; the granularity of each medicinal powder is 200 meshes;

step 2: heating the powder weighed in the step 1 in a vacuum heating furnace at 280 ℃ for 3 hours, and removing crystal water in the powder; putting the dried medicinal powder into a powder mixer for fully mixing for 4 h;

and step 3: a pure nickel strip is used as a welding skin, oil on the surface of the pure nickel strip is removed by alcohol, the powder prepared in the step 2 is wrapped in the pure nickel strip by flux-cored wire drawing equipment, and the aperture of a first drawing die is 2.6 mm; in the step 3, the thickness of the nickel strap is 0.4mm, and the width of the nickel strap is 7 mm; the filling rate of the flux-cored wire is controlled at 30 wt.%.

And 4, step 4: after the first process is finished, the aperture of the die is reduced in sequence, and finally the flux-cored wire with the diameter of 1.0mm is obtained.

And 5: and after the flux-cored wire is drawn, the flux-cored wire is wound on a wire reel through a wire winding machine and finally sealed in a flux-cored wire vacuum packaging bag for later use.

The nickel-chromium-based welding wire prepared in the embodiment 4 is used for welding the copper-steel composite plate, wherein two sides of the composite plate are respectively provided with asymmetric V-shaped grooves, the angle of the copper side groove is 90 degrees, the angle of the steel side groove is 50 degrees, the distance between the bottom of the copper side groove and the interface of the copper-steel composite plate is 1mm, and 2 layers of welding seams are adopted for welding the transition layer. The groove pattern is shown in fig. 1. The composite plate welding sequence is shown in fig. 2: firstly, welding a steel layer, wherein the welding material is an ER50-6 welding wire (the diameter is 1.2mm), and the welding current is 150-160A; then, welding a transition layer, adopting the flux-cored wire of the invention, welding current is 100-120A, and welding 2 layers of welding seams; and finally, welding the copper side, wherein the welding material is ERCuSi-Al (the diameter is 1.2mm), and the welding current is 200-250A.

Through tests, the tensile strength of the welded joint of the copper-steel composite plate is 367MPa, and the elongation is 17%.

Example 5

Step 1: weighing the following medicinal powder in percentage by mass: 45.0 percent of Cr powder, 30.0 percent of Nb powder and 25.0 percent of Mo powder, wherein the sum of the mass percentages of the components is 100 percent; the granularity of each medicinal powder is 100 meshes;

step 2: heating the powder weighed in the step 1 in a vacuum heating furnace at 270 ℃ for 2 hours, and removing crystal water in the powder; putting the dried medicinal powder into a powder mixer for fully mixing for 3 h;

and step 3: a pure nickel strip is used as a welding skin, oil on the surface of the pure nickel strip is removed by alcohol, the powder prepared in the step 2 is wrapped in the pure nickel strip by flux-cored wire drawing equipment, and the aperture of a first drawing die is 2.6 mm; in the step 3, the thickness of the nickel strap is 0.4mm, and the width of the nickel strap is 7 mm; the filling rate of the flux-cored wire is controlled at 25 wt.%.

And 4, step 4: after the first process is finished, the aperture of the die is reduced in sequence, and finally the flux-cored wire with the diameter of 1.2mm is obtained.

And 5: and after the flux-cored wire is drawn, the flux-cored wire is wound on a wire reel through a wire winding machine and finally sealed in a flux-cored wire vacuum packaging bag for later use.

The nickel-chromium-based welding wire prepared in example 5 is used for welding a copper-steel composite plate, wherein asymmetric V-shaped grooves are respectively formed in two sides of the composite plate, the angle of the copper side groove is 90 degrees, the angle of the steel side groove is 50 degrees, the distance between the bottom of the copper side groove and the interface of the copper-steel composite plate is 3mm, and 2 layers of welding seams are adopted for welding a transition layer. The groove pattern is shown in fig. 1. The composite plate welding sequence is shown in fig. 2: firstly, welding a steel layer, wherein the welding material is an ER50-6 welding wire (the diameter is 1.2mm), and the welding current is 150-160A; then, welding a transition layer, adopting the flux-cored wire of the invention, welding current is 100-120A, and welding 2 layers of welding seams; and finally, welding the copper side, wherein the welding material is ERCuSi-Al (the diameter is 1.2mm), and the welding current is 200-250A.

Through tests, the tensile strength of the welding joint of the copper-steel composite plate is 378MPa, and the elongation is 15%.