阅读说明：本技术 一种镍基合金的焊接方法 (Welding method of nickel-based alloy ) 是由 武承江 罗虎云 程锦鹏 于 2021-07-20 设计创作，主要内容包括：本发明为一种镍基合金的焊接方法。一种镍基合金的焊接方法,包括以下步骤：(1)对被焊工件进行处理,去除表面氧化物、油污,并打磨破口处；(2)在绝氧条件下,先采用哈氏合金对裂缝进行填充,再采用与所述的被焊工件材质相同的焊丝进行焊接；(3)焊接完成后,进行保温缓冷处理,至室温后,进行焊接效果检测。本发明所述的一种镍基合金的焊接方法,采用哈氏合金焊丝代替800H焊条,并结合本发明特有的焊接工艺,解决了焊缝经常出现裂纹的问题。(The invention relates to a welding method of a nickel-based alloy. A welding method of nickel-based alloy comprises the following steps: (1) treating the welded workpiece, removing surface oxides and oil stains, and polishing a cut; (2) under the anaerobic condition, filling cracks with Hastelloy, and welding with a welding wire made of the same material as the workpiece to be welded; (3) and after welding, carrying out heat preservation and slow cooling treatment, and detecting the welding effect after the temperature is reduced to room temperature. According to the welding method of the nickel-based alloy, the hastelloy welding wire is adopted to replace an 800H welding rod, and the special welding process is combined, so that the problem that cracks often appear in a welding line is solved.)

1. A welding method of a nickel-based alloy is characterized by comprising the following steps:

(1) treating the welded workpiece, removing surface oxides and oil stains, and polishing a cut;

(2) under the anaerobic condition, filling cracks with Hastelloy, and welding with a welding wire made of the same material as the workpiece to be welded;

(3) and after welding, carrying out heat preservation and slow cooling treatment, and detecting the welding effect after the temperature is reduced to room temperature.

2. The welding method according to claim 1,

in the step (2), the anaerobic condition is as follows: introducing argon gas, wherein the gas flow is 8-15L/min, and the wind speed is not more than 2 m/s.

3. The welding method according to claim 2,

in the step (2), the argon flow on the front surface of the welded workpiece is 8-10L/min, and the argon flow on the back surface of the welded workpiece is 10-12L/min.

4. The welding method according to claim 1,

in the step (2), during welding, the included angle between the welding gun and the workpiece to be welded is 60 degrees, and the included angle between the welding wire and the workpiece to be welded is 30 degrees.

5. The welding method according to claim 1,

in the step (2), the ambient temperature is not lower than 0 ℃.

6. The welding method according to claim 5,

in the step (2), the welding temperature is within 100 ℃.

7. The welding method according to claim 1,

and (3) in the step (2), welding is carried out in a low-current multilayer multi-pass welding mode.

8. The welding method according to claim 7,

in the step (2), the oxidizing slag on the surface is removed after each welding of each layer is finished, joints of each welding of each layer are staggered, and penetration detection is carried out after each welding of each layer and various defects on the surface are eliminated.

9. The welding method according to claim 7,

in the step (2), short arc welding is adopted.

10. The welding method according to claim 9,

in the step (2), the welding current is 80-110A, the arc voltage is 12-14V, and the welding speed is 7-10 cm/min.

Technical Field

The invention particularly relates to a welding method of a nickel-based alloy.

Background

Nickel and nickel-based alloys not only have thermal strength at high temperatures, but also have high corrosion resistance under the action of a medium. Therefore, the welding technology of nickel-based alloy and its special welding material have occupied an important position in industry. Nickel and nickel-based alloys are rapidly developed with the rise of aviation, nuclear and petrochemical industries, and have become indispensable important materials in the industrial production field.

Five major families of commonly used nickel-based alloys: inconel (Ni-Cr-Fe system), Monel (Ni-Cu system), Incoloy (Fe-Ni-Cr system), Hastelloy (Ni-Mo or Ni-Cr-Mo system), Hastelloy (BCG system). The incoloy nickel-based alloy has the characteristics of corrosion resistance, high-temperature oxidation resistance, thermal fatigue resistance, high-temperature impact resistance, pressure resistance and low-temperature mechanical property. Therefore, the nickel-based alloys that we are currently most exposed to are the incoloy series.

The welding method of the nickel-based alloy comprises the following steps: and welding the crack and the crevasse by adopting a welding wire made of the same material as the nickel-based alloy. However, since the nickel-based alloy has a large linear expansion coefficient (between austenitic stainless steel and plain carbon steel), some impurity elements and low-melting point substances in the weld joint are easy to segregate and accumulate among grains during welding. And a eutectic with low melting point is formed with nickel in the solidification process of a molten pool, so that the welding seam is easy to generate hot cracks after welding.

In view of the above, the invention provides a welding method of a nickel-based alloy, which can solve the problem that a welding seam is easy to generate cracks after welding.

Disclosure of Invention

The invention aims to provide a welding method of a nickel-based alloy, which uses a Hastelloy alloy as a filling layer between a welded workpiece and a welding wire layer with the same material as the welded workpiece, and solves the problem that cracks are easy to occur on a welding seam after welding.

In order to realize the purpose, the adopted technical scheme is as follows:

a welding method of nickel-based alloy comprises the following steps:

(1) treating the welded workpiece, removing surface oxides and oil stains, and polishing a cut;

(2) under the anaerobic condition, filling cracks with Hastelloy, and welding with a welding wire made of the same material as the workpiece to be welded;

(3) and after welding, carrying out heat preservation and slow cooling treatment, and detecting the welding effect after the temperature is reduced to room temperature.

Further, in the step (2), the anaerobic condition is as follows: introducing argon gas, wherein the gas flow is 8-15L/min, and the wind speed is not more than 2 m/s.

Still further, in the step (2), the argon gas flow on the front surface of the welded workpiece is 8-10L/min, and the argon gas flow on the back surface of the welded workpiece is 10-12L/min.

Further, in the step (2), during welding, an included angle between the welding gun and the workpiece to be welded is 60 degrees, and an included angle between the welding wire and the workpiece to be welded is 30 degrees.

Further, in the step (2), the ambient temperature is not lower than 0 ℃.

Still further, in the step (2), the welding temperature is within 100 ℃.

Furthermore, in the step (2), the welding is performed by adopting a low-current multi-layer and multi-pass welding mode.

And (3) further, in the step (2), removing oxidation slag on the surface after each layer is welded, staggering joints during each welding of each layer, and performing penetration detection after each welding layer is welded to eliminate various defects on the surface.

Still further, in the step (2), short arc welding is adopted.

Still further, in the step (2), the welding current is 80-110A, the arc voltage is 12-14V, and the welding speed is 7-10 cm/min.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention uses the hastelloy welding wire as a filling layer for welding the 800H base metal and then adopts 800H for welding. As the tensile strength, yield strength and elongation of the hastelloy are superior to those of an 800H (ERNiCr-3) material, the hastelloy can be used as a filling layer to well fill cracks of an 800H base material, so that cracks generated by intergranular corrosion and stress corrosion can be effectively relieved, and the problem of secondary cracking after welding is solved.

2. The welding process can improve the welding quality, eliminate the defects of air holes, sand holes and the like, and reduce the phenomenon of cracks on the welding line, thereby improving the utilization rate of equipment and reducing the cost.

Detailed Description

To further illustrate the welding method of a nickel-based alloy according to the present invention and achieve the desired objects, the following detailed description of the preferred embodiments, structures, features and effects thereof will be made with reference to the accompanying drawings. In the following description, different "one embodiment" or "an embodiment" refers to not necessarily the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Before describing in detail the welding method of a nickel-based alloy according to the present invention, it is necessary to further describe the related materials mentioned in the present invention to achieve better results.

The typical nickel base alloy content is shown in table 1.

TABLE 1

With the knowledge of the relevant materials mentioned in the present invention, the following will describe in further detail a method for welding a nickel-based alloy according to the present invention with reference to specific examples:

when the nickel-based alloy has obvious cracks and crevasses, a plurality of cracks which can not be seen by naked eyes also exist. In the prior art, welding wires with the same material as a workpiece to be welded are generally adopted to weld the workpiece to be welded. However, the method cannot well treat the cracks invisible to naked eyes, and because the linear expansion coefficient of the nickel-based alloy is large, some impurity elements and low-melting-point substances in the welding seam are easy to segregate and gather among crystals during welding, so that the welding seam is easy to crack again at the same position after being treated. According to the technical scheme, a Hastelloy layer is filled between the welded workpiece and the welding wire layer made of the same material as the welded workpiece, and the problem of re-cracking of cracks after welding can be well solved by combining corresponding technical parameters.

The technical scheme of the invention is as follows:

a welding method of nickel-based alloy comprises the following steps:

(1) treating the welded workpiece, removing surface oxides and oil stains, and polishing a cut;

(2) under the anaerobic condition, filling cracks with Hastelloy, and welding with a welding wire made of the same material as the workpiece to be welded;

(3) and after welding, carrying out heat preservation and slow cooling treatment, and detecting the welding effect after the temperature is reduced to room temperature.

Preferably, in the step (2), the anaerobic conditions are as follows: introducing argon gas, wherein the gas flow is 8-15L/min, and the wind speed is not more than 2 m/s.

Further preferably, in the step (2), the argon gas flow on the front surface of the welded workpiece is 8-10L/min, and the argon gas flow on the back surface of the welded workpiece is 10-12L/min.

Preferably, in the step (2), during welding, an included angle between the welding gun and the workpiece to be welded is 60 °, and an included angle between the welding wire and the workpiece to be welded is 30 °.

Preferably, in the step (2), the ambient temperature is not lower than 0 ℃.

Further preferably, in the step (2), the welding temperature is within 100 ℃.

Preferably, in the step (2), the welding is performed by a low-current multi-layer multi-pass welding method.

Further preferably, in the step (2), the oxidized slag on the surface is removed after each layer is finished, the joints of each layer are staggered during each welding, and penetration detection is performed after each layer is welded to eliminate various defects on the surface.

Further preferably, in the step (2), short arc welding is adopted.

Further preferably, in the step (2), the welding current is 80-110A, the arc voltage is 12-14V, and the welding speed is 7-10 cm/min.

Example 1.

The specific operation steps are as follows:

(1) before welding 800H, the oxide and oil stain on the surface of the metal to be welded and the two sides of the cut are polished to be within 50mm by a special angle polishing sheet for stainless steel.

(2) Under the anaerobic condition, the hastelloy is adopted to fill the crack, and then the crack is welded with an 800H welding wire.

Argon with the purity of more than or equal to 99.99 percent is introduced as protective gas during TIG welding, the gas flow is kept at 8-15L/min, and the wind speed is not more than 2 m/s.

The filling metal is a hastelloy material (ERNiCrMo-4), and a layer (ERNiCrMo-4) is overlaid when the nickel-based alloy material is welded, so that cracks generated by intergranular corrosion and stress corrosion can be effectively relieved.

During welding operation, the welding wire should not directly invade into the molten pool, and the welding material should be positioned in front of the tungsten electrode and fed while being melted, so that the end of the welding material is always in the argon protection range. The current should not be too large during welding.

(3) And (3) after the welding of the whole welding line is finished, keeping the temperature at 300 ℃ and slowly cooling, carrying out PT detection after slowly cooling to room temperature, and carrying out next RT detection after no defect exists.

In the preferred embodiment, in order to ensure the penetration, a joint form with a large bevel angle and a small truncated edge should be selected. The technological parameters and the welding angle are controlled finely during welding, the included angle between a welding gun and a workpiece is 60 degrees, and the included angle between a welding wire and the workpiece is 30 degrees.

In the preferred embodiment, no matter backing welding or interlayer welding is carried out during welding, the whole argon protection is required for the welding back surface to prevent oxidation. If necessary, an auxiliary conveying protective gas hood can be added on the rear side of the welding tip for enhancing the protective effect, namely the welding front side.

The argon flow of the front surface of the welded workpiece is 8-10L/min, and the argon flow of the back surface of the welded workpiece is 10-12L/min.

In the preferred embodiment, during the welding process, the ambient temperature is not lower than 0 ℃, and the temperature needs to be preheated to 20-30 ℃ before welding when the ambient temperature is lower than 0 ℃. And the temperature between filling layers is controlled within 100 ℃, namely the welding temperature is within 100 ℃.

In the preferred embodiment, the welding pool is very viscous and has a shallow penetration depth, and the increase of the welding current cannot obviously improve the fluidity of the metal and increase the penetration depth, so in the step (2), the welding is carried out by adopting a low-current multilayer multi-pass welding mode. And removing oxidation slag on the surface of each layer after each layer is finished, staggering joints during each welding of each layer, and performing penetration detection and eliminating various defects on the surface after each layer is welded.

In this embodiment, it is further preferable that, in the step (2), short arc welding is adopted, and the heat input is reduced by reducing the arc voltage.

In this embodiment, it is further preferable that in the step (2), the welding current is 80-110A, the arc voltage is 12-14V, and the welding speed is 7-10 cm/min.

The specific technical parameters during welding are shown in Table 2.

TABLE 2

In the present embodiment, it is preferable to select a suitable welding material so as to adjust the alloy composition to provide a weld having a dual phase structure of austenite and ferrite and to limit the content of carbon as an impurity element in the welding material.

In the present embodiment, it is preferable to reduce the time for which the weld zone stays at a high temperature, and the longer the stay time is, the more severe the crack tends to be, and the higher the degree of alloying of the weld material becomes, the more likely thermal cracks are generated during welding.

Comparative example: the 800H welding wire is adopted to directly weld the 800H base metal, and the crevasse part is cracked again after half a year.

The example 1 of the invention is implemented in 2019 and 2 months, and the welded part still has no crack.

At present, in the process of welding the nickel-based alloy base metal, an 800H (ERNiCr-3) welding rod is generally adopted for welding, and the welding rod made of Hastelloyalloy material is adopted for welding the nickel-based alloy base metal. As the tensile strength, yield strength and elongation of the hastelloy are superior to those of an 800H (ERNiCr-3) material, the hastelloy can be used as a filling layer to well fill cracks of an 800H base material, so that cracks generated by intergranular corrosion and stress corrosion can be effectively relieved, and the problem of secondary cracking after welding is solved. Therefore, the hastelloy welding rod is more suitable for welding nickel-based alloy materials. And the special welding process of the invention is combined, thereby improving the welding quality, eliminating the defects of air holes, sand holes and the like, reducing the phenomenon of cracks on the welding line, improving the utilization rate of equipment and reducing the cost.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.