阅读说明：本技术 一种激光高熵化填粉焊接抑制焊缝脆性金属间化合物生成的方法 (Method for inhibiting generation of brittle intermetallic compounds of weld joint by laser high-entropy powder filling welding ) 是由 刘德佳 郭瑞 沈明学 唐延川 胡勇 赵龙志 于 2020-06-04 设计创作，主要内容包括：本发明公开了一种激光高熵化填粉焊接抑制焊缝脆性金属间化合物生成的新方法,它属于焊接技术领域。由五种或五种以上的金属粉末,按特定比例混合均匀后,采用同轴送粉方式,在激光热源作用下实现异种金属的激光高熵化填粉焊接。所形成的焊缝金属由多主元组成,并具备高混合熵特征,从而抑制焊缝脆性金属间化合物的生成,使异种金属焊缝接头具有高强、高韧的特性。本发明具有以下优势：(1)可简单快捷地改变焊缝熔池的热力学环境,充分利用高混合熵效应调控焊缝金属的微观结构与接头性能；(2)可针对不同被焊材料的焊接性能,设计并改变高熵化焊缝金属的元素组成与成分配比,从而达到抑制焊缝金属间化合物生成的目的,具有柔性制造的特征。(The invention discloses a novel method for inhibiting the generation of brittle intermetallic compounds of a welding seam by laser high-entropy powder filling welding, belonging to the technical field of welding. Five or more than five kinds of metal powder are uniformly mixed according to a specific proportion, and then a coaxial powder feeding mode is adopted to realize laser high-entropy powder filling welding of dissimilar metals under the action of a laser heat source. The formed weld metal consists of multiple principal elements and has the characteristic of high mixed entropy, so that the generation of brittle intermetallic compounds of the weld is inhibited, and the dissimilar metal weld joint has the characteristics of high strength and high toughness. The invention has the following advantages: (1) the thermodynamic environment of a weld pool can be changed simply and quickly, and the microstructure and the joint performance of weld metal are regulated and controlled by fully utilizing the high mixing entropy effect; (2) the element composition and the component proportion of the high-entropy welding seam metal can be designed and changed according to the welding performance of different welded materials, so that the aim of inhibiting the generation of the welding seam intermetallic compound is fulfilled, and the flexible welding seam metal has the characteristic of flexible manufacturing.)

1. A method for inhibiting the generation of brittle intermetallic compounds of a welding seam by laser high-entropy powder filling welding is characterized by comprising the following steps: adopting five or more than five metal powders, uniformly mixing the metal powders according to a specific atomic ratio, conveying the metal mixed powders to a welding area by adopting a coaxial powder feeding mode, and realizing laser high-entropy connection of a welded workpiece under the action of a laser welding heat source; the formed weld metal is composed of multiple principal elements and has the characteristic of high mixed entropy, and the generation of weld intermetallic compounds is inhibited through the characteristic of high mixed entropy of the weld metal, so that the toughness of a welded joint is improved.

2. The method for inhibiting the generation of the brittle intermetallic compounds of the welding seam by the laser high-entropy powder filling welding according to claim 1, characterized in that: the mixed powder of the five or more metals is composed of 5-45 atomic percent of various elements and can be adjusted according to the required structure performance of a welding joint, and the granularity of the mixed powder is 100-300 meshes.

3. The method for inhibiting the generation of the brittle intermetallic compounds of the welding seam by the laser high-entropy powder filling welding according to claim 1, characterized in that: the welded workpiece can be made of the same material, including stainless steel, nickel-based alloy and titanium-aluminum-based alloy; or may be a dissimilar material including aluminum alloys and steel, steel and nickel based alloys, steel and copper.

4. The method for inhibiting the generation of the brittle intermetallic compounds of the welding seam by the laser high-entropy powder filling welding according to claim 1, characterized in that: the metal mixed powder and the workpiece to be welded are melted under the action of the laser welding heat source, and the formed welding joint is a fusion welding joint.

5. The method for inhibiting the generation of the brittle intermetallic compounds of the welding seam by the laser high-entropy powder filling welding according to claim 1, characterized in that: in the laser welding process, argon protection is adopted, and the welding process parameters are as follows: the diameter of a laser spot is 1.5-2.5 mm, the laser power is 800-1200W, the welding speed is 200-400 mm/min, and the powder feeding rate is 10-20 g/min.

Technical Field

The invention belongs to the technical field of welding, and relates to a method for inhibiting the generation of brittle intermetallic compounds of a welding seam by laser high-entropy powder filling welding.

Background

Welding is the foundation of manufacturing industry, and the microstructure and the joint performance of a welding joint are related to the safety and reliability of various manufactured products. However, the microstructure of the material in the rapid heating and cooling state is significantly changed during welding, and particularly, when certain materials which are difficult to weld (such as nickel-based alloy and titanium-aluminum-based alloy) or dissimilar metals (such as aluminum alloy and steel, steel and nickel-based alloy, and steel and copper) are welded, brittle intermetallic compounds are easily generated at the weld joint, and the service performance of the welded joint is seriously reduced. Therefore, the exploration of a method capable of effectively inhibiting the generation of the intermetallic compound of the welding line has very important significance for improving the mechanical property of the welding joint of the difficult-to-weld metal or dissimilar metal.

At present, documents indicate that high mixed entropy formed by five or more main elements can avoid generating intermetallic compounds by phase separation through multi-element diffusion and redistribution, and delay nucleation and growth of precipitated phases, so as to promote the alloy to form a simple solid solution structure or even an amorphous structure. For example, typical FeCoCrNiAl high-entropy alloy contains a large amount of Fe and Al elements, and even if the two elements are in direct contact in a liquid phase in laser deposition or arc melting, the alloy does not generate Fe-Al intermetallic compounds but forms a simple solid solution structure. From the thermodynamic analysis, it is considered that the formation of intermetallic compounds is avoided because the gibbs free energy of the multi-element high-entropy alloy to form a solid solution is lower than that to form the intermetallic compounds. Therefore, the thermodynamic condition for generating the intermetallic compound of the welding seam is changed by increasing the mixed entropy value of the welding seam metal by utilizing the design idea of high entropy, and the generation of the intermetallic compound of the welding seam is fundamentally inhibited, so that the obdurability of the metal welding joint is improved, and the method has important significance for industrial application.

At present, the researchers have tried to apply the high-entropy alloy to the welding field, for example, patents for preparing the high-entropy alloy welding wire and the related method include "high-entropy alloy welding wire for welding titanium-steel and the preparation method thereof (CN 201310476898.5)", "high-entropy alloy welding wire and the application for TIG welding titanium/stainless steel (CN 201410787004.9)", "high-entropy alloy welding wire and the preparation method for TIG welding titanium and steel (CN 201310614033.0)", "high-entropy alloy welding wire and the application for TIG welding titanium/low-carbon steel (CN 201410787157.3)". Patents related to the preparation of high-entropy alloy solders and related methods include "amorphous high-entropy alloy solder and preparation method for brazing tantalum and steel (CN 201410729341.2)", "high-entropy alloy solder and preparation method for welding hard alloy and steel (CN 200910022545.1)", "high-entropy alloy solder and preparation method for welding copper and aluminum (CN 200910022543.2)", "high-entropy solder for brazing non-oxide ceramics and composites thereof and preparation method thereof (201210207740.3)"; other patents of the high entropy effect welding material and the method include 'a method for welding titanium and steel by applying the high entropy effect and a welding material (CN 201210143862.0)' a material and a method for welding TA2/0Cr18Ni9Ti by applying the high entropy effect (CN201210143238.0) 'a process method for filling spot welding stainless steel high entropy alloy powder and filling spot welding stainless steel by using the high entropy alloy powder (201310142899.6)'.

However, the essence of the above patent is that the high-entropy alloy is used as a barrier layer between dissimilar metals, the mutual contact between elements formed by intermetallic compounds is reduced by utilizing the diffusion retarding capability of the high-entropy alloy, and the aim of reducing the generation of the intermetallic compounds of the weld seam is achieved by virtue of the advantage that the elements have certain solid solution amount in the high-entropy alloy. In addition, in terms of the preparation form of the welding filling material, the preparation method is characterized in that a multi-principal-element high-entropy alloy block is prepared, and then a high-entropy alloy welding rod, a foil strip and brazing filler metal are prepared, so that the process flow is long. When designing the high-entropy alloy solder, the melting point of the solder and the wettability of the solder and a base metal need to be considered, so that the selection of the components of the high-entropy welding line is greatly limited. The element types and contents of weld metal cannot be flexibly changed during welding, the microstructure and joint performance of the high-entropy welding seam are not easy to regulate and control, and the applicability of the high-entropy welding process is reduced.

Disclosure of Invention

The invention aims to solve the problem that when certain materials which are difficult to weld (such as nickel-based alloy and titanium-aluminum-based alloy) or dissimilar metals (such as aluminum alloy and steel, steel and nickel-based alloy and steel and copper) are welded, brittle intermetallic compounds are easily generated in a welding seam, and provides a laser high-entropy powder filling welding method for inhibiting the generation of the brittle intermetallic compounds in the welding seam so as to improve the obdurability of a welding joint.

The technical scheme adopted by the invention for solving the technical problem is as follows: a method for inhibiting the formation of brittle intermetallic compounds of a welding seam by laser high-entropy powder filling welding adopts five or more than five metal powders, and after the five metal powders are uniformly mixed according to a specific atomic proportion, the metal mixed powders are conveyed to a welding area by adopting a coaxial powder feeding mode, and the laser high-entropy connection of a welded workpiece is realized under the action of a laser welding heat source; the formed weld metal is composed of multiple principal elements and has the characteristic of high mixed entropy, and the generation of weld intermetallic compounds is inhibited through the characteristic of high mixed entropy of the weld metal, so that the toughness of a welded joint is improved.

Furthermore, the mixed powder of five or more metals is composed of 5-45 atomic percent of various elements, can be adjusted according to the required structure performance of a welding joint, and has the granularity of 100-300 meshes.

Furthermore, the welded workpiece can be made of the same material, including stainless steel, nickel-based alloy and titanium-aluminum-based alloy; or may be a dissimilar material including aluminum alloys and steel, steel and nickel based alloys, steel and copper.

Further, the metal mixed powder and the workpiece to be welded are melted under the action of the laser welding heat source, and the formed welding joint is a fusion welding joint.

Further, in the laser welding process, argon gas protection is adopted, and the welding process parameters are as follows: the diameter of a laser spot is 1.5-2.5 mm, the laser power is 800-1200W, the welding speed is 200-400 mm/min, and the powder feeding rate is 10-20 g/min.

In the invention, the intermetallic compound forming elements are directly used as the forming elements of the high-entropy welding seam, the direct contact of the forming elements of the intermetallic compound in a welding seam molten pool is not needed, and a high-mixed-entropy thermodynamic environment is formed by five or more main elements of the welding seam, so that the thermodynamic condition for generating the intermetallic compound of the welding seam is changed, and the generation of the intermetallic compound of the welding seam is fundamentally inhibited.

Therefore, compared with the prior patents and documents, the method for inhibiting the generation of the brittle intermetallic compounds of the welding seam by the laser high-entropy powder filling welding can directly contain a plurality of metal mixed powders, and realizes the welding of materials by adopting a coaxial powder feeding mode in a laser welding heat source. And the element composition and the component proportion of the high-entropy welding seam metal can be designed and changed according to the welding metallurgical property of the welded material, the thermodynamic environment of a welding seam molten pool can be changed simply and quickly, the microstructure and the joint performance of the welding seam metal can be improved by fully utilizing the high-mixed entropy effect, and the universality is stronger. And the laser welding also has the advantages of high energy density, quick heat input, small heat affected zone and better mechanical property of the obtained joint.

The invention has the beneficial effects that: compared with the prior art, the method for inhibiting the generation of the brittle intermetallic compounds of the welding seam by the laser high-entropy powder filling welding has the following advantages:

(1) the laser high-entropy filling powder welding is adopted to inhibit the generation of brittle intermetallic compounds of welding seams, and the welding can be directly carried out through mixed powder, so that the process of preparing high-entropy alloy welding rods, welding wires or brazing filler metals, intermediate layers and the like at the early stage is avoided, and the characteristics of high efficiency and flexible welding are achieved;

(2) the laser high-entropy powder filling welding is adopted to inhibit the generation of brittle intermetallic compounds of the welding seam, the thermodynamic environment of a welding seam molten pool can be changed simply and quickly, and the high-mixed entropy effect can be fully utilized to improve the microstructure and the joint performance of the welding seam metal;

(3) the laser high-entropy powder filling welding is adopted to inhibit the generation of brittle intermetallic compounds of the welding line, the elements formed by the intermetallic compounds are allowed to be directly contacted in a molten pool, the thermodynamic condition for generating the intermetallic compounds is changed by increasing the mixed entropy value of the welding line, the generation of the intermetallic compounds of the welding line is fundamentally inhibited, and the defect that the generation of the intermetallic compounds of the welding line is only partially reduced by utilizing the diffusion retardation of the high-entropy alloy by the predecessor is overcome;

(4) during welding, the welded workpiece and the filling material are melted, the selection range of the welded material is wider, and the connection strength of a welding joint is higher.

Drawings

FIG. 1 is a macroscopic view of laser high-entropy chemical powder filling welding 6005A aluminum alloy and 304 stainless steel.

FIG. 2 is a microstructure diagram of a weld joint of a 6005A aluminum alloy and 304 stainless steel by laser high-entropy chemical powder filling welding: (a) the aluminum to weld interface; (b) steel to weld interface.

FIG. 3 is a macroscopic view of laser high-entropy chemical powder filling welding Q235 and 304 stainless steel.

FIG. 4 is a diagram showing the microhardness distribution of laser high-entropy chemical powder filling welding Q235 and 304 stainless steel.

Detailed Description

The invention is further illustrated by the following specific examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention.