阅读说明：本技术 一种镁合金增材修复再制造的方法 (Magnesium alloy additive repairing remanufacturing method ) 是由 王晓明 朱建 任智强 王文宇 朱胜 周克兵 赵阳 韩国峰 田根 何东昱 臧艳 于 2021-09-08 设计创作，主要内容包括：本发明提供了一种镁合金增材修复再制造的方法,属于镁合金修复再制造技术领域。包括：镁合金零部件损伤表面的处理；测量损伤区域的几何参数,确定损伤体积,基于损伤体积确定增材修复的工艺；采用激光-电弧复合成形设备对机械打磨后的损伤件进行精确修复；将修复后的损伤件进行去应力退火；增材修复件的表面精修。本发明能够破除镁合金增材过程中的晶粒粗化,无热影响区,成形层晶粒细小,并且避免了气孔和裂纹等缺陷的产生,成形层的力学性能因晶粒细化较基体明显改善。(The invention provides a magnesium alloy additive repairing remanufacturing method, and belongs to the technical field of magnesium alloy repairing remanufacturing. The method comprises the following steps: treating the damaged surface of the magnesium alloy part; measuring geometric parameters of a damaged area, determining a damaged volume, and determining an additive repair process based on the damaged volume; accurately repairing the mechanically polished damaged part by adopting laser-electric arc composite forming equipment; carrying out stress relief annealing on the repaired damaged part; and (5) performing surface finishing on the additive repairing piece. The invention can break the coarsening of crystal grains in the magnesium alloy material increase process, has no heat influence area, has fine crystal grains of a forming layer, avoids the generation of defects such as air holes, cracks and the like, and obviously improves the mechanical property of the forming layer compared with a matrix due to the grain refinement.)

1. The method for remanufacturing the magnesium alloy through additive repair is characterized by comprising the following steps of:

treating the damaged surface of the magnesium alloy part;

measuring geometric parameters of a damaged area, determining a damaged volume, and determining an additive repair process based on the damaged volume;

accurately repairing the mechanically polished damaged part by adopting laser-electric arc composite forming equipment; the angle between the laser welding gun and the damaged surface is 90 degrees, and the angle between the arc welding gun and the damaged surface is 50-70 degrees; the arc current is 85-115A, the arc voltage is 15-20V, and the laser power is 1.5-3 KW; the used welding wire is a magnesium alloy welding wire with the diameter of 1-2 mm; the wire feeding speed is 2.4-4.8m/mim, and the welding speed is 1.2-2.4 m/mim; when multilayer accumulation is carried out, the interlayer waiting time is 10-20s, and the forming path is reciprocating;

carrying out stress relief annealing on the repaired damaged part;

and (5) performing surface finishing on the additive repairing piece.

2. The method for additive repair remanufacturing of a magnesium alloy component according to claim 1, wherein the treatment of the damaged surface of the magnesium alloy component comprises: and (3) machining the defect part of the magnesium alloy part, removing the defect until the fresh metal surface is exposed, and detecting whether the crack is polished completely by using a colorant flaw detection method for crack damage.

3. The method of additive repair remanufacturing of a magnesium alloy according to claim 1, wherein measuring a geometric parameter of the damaged area comprises: and measuring the geometric parameters of the damaged area by using a laser profilometer.

4. The method of additive repair remanufacturing of a magnesium alloy according to claim 1, wherein the process of additive repair comprises: when the width of the defect area is less than or equal to the width of the single-channel welding seam and the depth is less than the residual height, recovering the damage volume by adopting single-layer single-channel material increase; when the width of the defect area is less than or equal to the width of a single-channel welding seam and the depth is greater than or equal to the residual height, adopting multilayer single-channel material increase to recover the damaged volume; when the width of the defect area is larger than the width of a single-channel welding seam and the depth is smaller than the residual height, restoring the lost volume by adopting single-layer multi-channel material increase; and when the width of the defect area is larger than the width of a single-channel welding seam and the depth is larger than or equal to the residual height, recovering the lost volume by adopting multilayer and multi-channel materials increase.

5. The method of additive repair remanufacturing of a magnesium alloy according to claim 1, wherein the surface finishing of the additive repair comprises: and (3) polishing and finishing the repaired surface of the damaged part by using 2000-mesh sand paper to restore the original geometric dimension and surface state of the damaged part.

6. The method of additive repair remanufacturing of a magnesium alloy according to claim 1, wherein the parameters of the stress relief anneal comprise: the annealing temperature is 150-200 ℃, and the annealing time is 30-90 min.

Technical Field

The invention belongs to the technical field of magnesium alloy repair and remanufacture, and relates to a magnesium alloy additive repair and remanufacture method.

Background

The magnesium alloy has the advantages of low density, high specific strength and specific stiffness, good casting performance, easy cutting and processing, strong damping and shock absorption performance, impact resistance, easy recovery, rich resources and the like, is a light-weight material which is highly accepted by governments, scientific research institutions and the business industry, and is gradually applied to modern industries such as automobile manufacturing, aerospace, rail transit and the like.

However, magnesium alloys present two major "bottlenecks": (1) the electrode potential of the magnesium alloy is very low, and the surface oxidation film is loose and not compact, so that the magnesium alloy parts are easy to be corroded and damaged in a large scale; (2) the magnesium alloy has low hardness and poor wear resistance, and the surface is very easy to generate sliding wear or fretting wear, so that the magnesium alloy parts/components generate wear cracks and even are locally damaged. The two problems seriously limit the development and application of the magnesium alloy, so that the surface damage of the magnesium alloy part is repaired, the damaged part can be recycled, the economic cost is saved, the social benefit is generated, and the wider industrial application of the magnesium alloy can be promoted.

Currently, the additive manufacturing of magnesium alloy mainly adopts a traditional surfacing and cladding process and a novel laser forming technology, for example, cn201410247205.x discloses a surfacing forming remanufacturing method of a magnesium alloy part, and remanufactures the magnesium alloy part by adopting the traditional surfacing process. The invention discloses a high-performance magnesium-based composite material based on laser 3D printing forming and a preparation method thereof, and the high-performance magnesium-based composite material is used for repairing magnesium alloy parts by adopting a novel laser forming technology. CN201810464169.0 discloses a CMT-ultrasonic vibration composite additive manufacturing method, which performs ultrasonic vibration on a substrate while performing CMT arc additive manufacturing, and after applying the ultrasonic vibration, a component with a fine and uniform non-dendritic structure can be obtained. CN201811624111.4 discloses a method for manufacturing high-performance magnesium alloy parts, which comprises the steps of drying and screening magnesium alloy powder to obtain fine powder, and then filling the fine powder into equipment for melting. Printing and forming to obtain the magnesium alloy part. CN201910079686.0 discloses an electric arc additive manufacturing method for magnesium alloy wires, which is used for repairing magnesium alloy parts. CN201911393713.8 discloses an arc additive manufacturing method of a magnesium alloy structural part and equipment used by the method, and the method is used for repairing the magnesium alloy structural part.

The method for additive repairing and remanufacturing of the magnesium alloy part has the following technical defects: the traditional surfacing and cladding process and the novel laser forming technology have unsatisfactory repairing effect on magnesium alloy parts, and the repaired parts can not meet the service requirement, which is determined by the special physical and chemical properties of the magnesium alloy. On one hand, the requirement of magnesium alloy on the remanufacturing forming technology is very strict, the traditional methods such as surfacing or cladding have low heating efficiency, long heating time and large heat input to a matrix, so that the magnesium alloy part has many defects and poor performance when being repaired, and is not suitable for the remanufacturing of the magnesium alloy part; on the other hand, the novel laser heat source forming technology has the outstanding advantages of high power density, high automation degree, small influence on matrix structure performance, high repair precision, excellent repair area performance and the like, but the magnesium alloy has extremely high laser reflectivity, low laser energy utilization rate, large energy loss and poor forming effect, and the magnesium alloy has low melting point, is easy to oxidize and has high dilution rate, and the selection of laser heat source repair materials is limited.

Disclosure of Invention

In order to overcome the bottleneck that damaged parts of magnesium alloy are difficult to repair, the invention provides a method for additive remanufacturing of magnesium alloy.

The technical scheme provided by the invention is as follows:

the invention provides a magnesium alloy additive remanufacturing method which is implemented according to the following steps:

treating the damaged surface of the magnesium alloy part;

measuring geometric parameters of a damaged area, determining a damaged volume, and determining an additive repair process based on the damaged volume;

accurately repairing the mechanically polished damaged part by adopting laser-electric arc composite forming equipment; the angle between the laser welding gun and the damaged surface is 90 degrees, and the angle between the arc welding gun and the damaged surface is 50-70 degrees; the arc current is 85-115A, the arc voltage is 15-20V, and the laser power is 1.5-3 KW; the used welding wire is a magnesium alloy welding wire with the diameter of 1-2 mm; the wire feeding speed is 2.4-4.8m/mim, and the welding speed is 1.2-2.4 m/mim; when multilayer accumulation is carried out, the interlayer waiting time is 10-20s, and the forming path is reciprocating;

carrying out stress relief annealing on the repaired damaged part;

and (5) performing surface finishing on the additive repairing piece.

Further, the treatment of the damaged surface of the magnesium alloy part comprises the following steps: and (3) machining the defect part of the magnesium alloy part, removing the defect until the fresh metal surface is exposed, and detecting whether the crack is polished completely by using a colorant flaw detection method for crack damage.

Further, measuring geometric parameters of the damaged area includes: and measuring the geometric parameters of the damaged area by using a laser profilometer.

Further, a process for additive repair, comprising: when the width of the defect area is less than or equal to the width of the single-channel welding seam and the depth is less than the residual height, recovering the damage volume by adopting single-layer single-channel material increase; when the width of the defect area is less than or equal to the width of a single-channel welding seam and the depth is greater than or equal to the residual height, adopting multilayer single-channel material increase to recover the damaged volume; when the width of the defect area is larger than the width of a single-channel welding seam and the depth is smaller than the residual height, restoring the lost volume by adopting single-layer multi-channel material increase; and when the width of the defect area is larger than the width of a single-channel welding seam and the depth is larger than or equal to the residual height, recovering the lost volume by adopting multilayer and multi-channel materials increase.

Further, the surface finishing of additive repair, includes: and (3) polishing and finishing the repaired surface of the damaged part by using 2000-mesh sand paper to restore the original geometric dimension and surface state of the damaged part.

Further, the parameters of the stress relief annealing include: the annealing temperature is 150-200 ℃, and the annealing time is 30-90 min.

Compared with the prior art, the invention has the advantages that: the laser-arc composite forming technology is applied to additive repair remanufacturing of magnesium alloy damaged parts, the method is laser-arc two-heat source composite fuse forming, and damaged parts are made of magnesium alloys of different grades. The two processes are crossed and fused, and the advantages are complemented, so that the effect of 1+1>2 is finally achieved. The invention can break the coarsening of crystal grains in the magnesium alloy material increase process, has no heat influence area, has fine crystal grains of a forming layer, avoids the generation of defects such as air holes, cracks and the like, and obviously improves the mechanical property of the forming layer compared with a matrix due to the grain refinement. The method has the advantages of simple process flow, simple and convenient operation, high efficiency and high precision, is suitable for repairing and remanufacturing the magnesium alloy zero damage part in the fields of automobile aerospace, rail transit, engineering machinery and the like, and has important significance for saving the use cost of the magnesium alloy and widening the application range of the magnesium alloy.

Drawings

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

Fig. 1 is a schematic diagram of the principle of laser-arc hybrid forming employed in the embodiment of the present invention.

FIG. 2 is an SEM image of the repair layer at the interface with the original substrate in an embodiment of the invention.

FIG. 3 is a graph of hardness distribution at the interface of a repair layer and an original substrate in an embodiment of the invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

At present, the application research of laser and electric arc composite heat source manufacturing mainly aims at the aspects of thin plate welding, medium steel plate welding, copper-aluminum alloy high-reflection material welding and the like in the industries of automobiles, shipbuilding, aviation, petroleum pipelines and the like, and the research and application related to additive manufacturing, particularly additive remanufacturing are few. The method has positive significance for the cyclic application of magnesium alloy loss parts by developing the magnesium alloy laser-electric arc composite additive remanufacturing, and can promote the application field of magnesium alloys.

The invention adopts laser-electric arc composite forming technology to repair and remanufacture the magnesium alloy, organically combines two different heat sources of laser and electric arc together, and compared with the single heat source forming of the laser and the electric arc, the invention has the following advantages: (1) the energy utilization rate of laser and electric arc is improved, and the method is more suitable for forming high-laser-reflection materials such as magnesium alloy and the like; (2) the depth of a molten pool is increased, the welding bridging property is improved, and the welding speed is increased; (3) in the forming process of the laser-electric arc composite heat source, the laser irradiates the molten pool to evaporate and ionize the metal, so that the welding stability in the forming process is improved; (4) the stress is reduced, the weld forming is improved, and the forming precision can be improved; (5) the forming defects are reduced; (6) improve the microstructure and performance of the forming layer. The technology not only gives full play to the respective advantages of the two heat sources, but also mutually makes up the respective defects, and has important industrial application value in the aspects of requirements of magnesium alloy additive repair remanufacturing technology, forming quality, production efficiency, production cost and the like.

When laser-electric arc composite forming equipment is used for accurately repairing the damaged part after mechanical polishing, the angle between a laser welding gun and the damaged surface is 90 degrees, and the angle between an electric arc welding gun and the damaged surface is 50-70 degrees; the arc current is 85-115A, the arc voltage is 15-20V, and the laser power is 1.5-3 KW; the used welding wire is a magnesium alloy welding wire with the diameter of 1-2 mm; the wire feeding speed is 2.4-4.8m/mim, and the welding speed is 1.2-2.4 m/mim; when multilayer accumulation is carried out, the interlayer waiting time is 10-20s, and the forming path is a reciprocating type.

Before accurately repairing a damaged part after mechanical polishing by adopting laser-electric arc composite forming equipment, firstly measuring geometric parameters of a damaged area, determining the damaged volume, and determining an additive repairing process based on the damaged volume, wherein the additive repairing process comprises the following steps: the forming width of the single welding seam can reach 7mm, the residual height can reach 1mm, and when the width of the defect area is less than or equal to the width of the single welding seam and the depth is lower than the residual height, the damage volume is recovered by adopting single-layer single-channel material increase; when the width of the defect area is less than or equal to the width of a single-channel welding seam and the depth is greater than or equal to the residual height, adopting multilayer single-channel material increase to recover the damaged volume; when the width of the defect area is larger than the width of a single-channel welding seam and the depth is smaller than the residual height, restoring the lost volume by adopting single-layer multi-channel material increase; and when the width of the defect area is larger than the width of a single-channel welding seam and the depth is larger than or equal to the residual height, recovering the lost volume by adopting multilayer and multi-channel materials increase.

Example 1:

the magnesium alloy repairing and remanufacturing object in the embodiment is an airplane ZM5 flywheel part, the size damage is generated by corrosion and abrasion in a linkage mode in the using process, and the length, the width and the depth of a damaged area are respectively measured by a laser profilometer to be within the range of 30mm multiplied by 20mm multiplied by 2 mm. The method for remanufacturing the magnesium alloy additive repair remanufacturing object comprises the following steps of:

and S101, treating the damaged surface of the magnesium alloy part.

A groove with the length, the width and the depth of 31mm multiplied by 21mm multiplied by 3mm is formed at a damaged position by adopting a mechanical processing method, the defects and the surface corrosion/abrasion products thereof are removed until a fresh metal surface is exposed, and whether cracks are completely polished or not is detected by using a colorant flaw detection method for crack damage.

And S102, determining the geometrical characteristics and the volume based on the damage by adopting a multi-layer and multi-channel additive repairing process, wherein the time of waiting between layers is 10S.

S103, restoring the damaged volume of the part by using a laser-arc composite forming technology.

Accurately repairing the mechanically polished damaged part by adopting laser-MIG composite multilayer multi-channel additive, wherein the angle between a laser welding gun and the damaged surface is 90 degrees, and the angle between an arc welding gun and the damaged surface is 60 degrees; the arc current is 90A, the arc voltage is 15-20V, and the laser power is 2 KW; the welding wire used was a ZM5 welding wire, with a diameter of 1.2 mm; the wire feeding speed is 2.5m/mim, and the welding speed is 1.8 m/mim; the flow of the protective gas is 20L/min, and pure argon is adopted for protection.

And S104, stress relief annealing of the additive repairing part.

And (4) performing stress relief annealing on the repaired damaged part, wherein the annealing temperature is 150 ℃, and the annealing time is 60 min.

And S105, surface finishing of the additive repairing part.

And (3) polishing and finishing the surface of the repaired damaged part by using 2000-mesh abrasive paper, removing burrs, splashing and the like, and restoring the damaged part to the original geometric dimension and surface state.

The interface structure of the repair layer and the substrate was observed by a scanning electron microscope, and fig. 2 is an SEM image of the repair layer and the original substrate interface according to the present invention. Therefore, no crack or air hole is generated in the repair forming layer, and the metallographic structure is uniform and fine isometric crystal; since the cooling rate is fast during laser forming, no heat affected zone is formed near the interface.

The hardness of the repairing layer and the original substrate interface is tested by adopting a microhardness tester, the loading load is 20g, the loading time is 10s, each position area is tested for 10 times, and the average value is taken as the hardness of the area. FIG. 3 is a graph of the hardness distribution at the interface of the repair layer and the original substrate of the present invention, showing that the hardness of the formed layer is significantly increased compared to the substrate, because the sub-rapid solidification effect of the laser refines the grains in the formed region, thereby causing a fine grain strengthening phenomenon in the formed region.

Example 2:

the magnesium alloy repair remanufacturing object in the embodiment is an airplane ZM5 flywheel part, the size damage is generated by corrosion and abrasion in a linkage mode in the using process, and the length, the width and the depth of a damaged area are respectively measured by a laser profilometer to be within the range of 4mm multiplied by 2mm multiplied by 1 mm. The method for remanufacturing the magnesium alloy additive repair remanufacturing object comprises the following steps of:

s201, processing the damaged surface of the magnesium alloy part. A groove with the length, the width and the depth of 4.5mm multiplied by 2.5mm multiplied by 1.5mm is formed at a damaged position by adopting a mechanical processing method, the defects and the surface corrosion/abrasion products thereof are removed until a fresh metal surface is exposed, and whether cracks are completely polished or not is detected by using a colorant flaw detection method for the crack damage.

S202, determining an additive repairing process adopting two layers and a single channel based on the geometric characteristics and the volume of the damage.

And S203, restoring the damaged volume of the part by adopting a laser-arc composite forming technology.

Accurately repairing the mechanically polished damaged part by adopting a laser-MIG composite two-layer single-pass additive process, wherein the angle between a laser welding gun and the damaged surface is 90 degrees, and the angle between an electric arc welding gun and the damaged surface is 60 degrees; the arc current is 90A, the arc voltage is 15-20V, and the laser power is 2 KW; the welding wire used was a ZM5 welding wire, with a diameter of 1.2 mm; the wire feeding speed is 2.5m/mim, and the welding speed is 1.8 m/mim; the flow of the protective gas is 20L/min, and pure argon is adopted for protection. When multiple lapping is carried out, the selected lapping rate is 50 percent; when two layers are stacked, the waiting time between layers is 10s, and the forming path is a reciprocating type.

And S204, stress relief annealing of the additive repairing part.

And (4) performing stress relief annealing on the repaired damaged part, wherein the annealing temperature is 150 ℃, and the annealing time is 30 min.

S205, surface finishing of the additive repairing part.

And (3) polishing and finishing the surface of the repaired damaged part by using 2000-mesh abrasive paper, removing burrs, splashing and the like, and restoring the damaged part to the original geometric dimension and surface state.

The interface structure of the repair layer and the substrate was observed by a scanning electron microscope, and the obtained result was consistent with that of embodiment 1.

The hardness of the repairing layer and the original substrate interface is tested by adopting a microhardness tester, the loading load is 20g, the loading time is 10s, each position area is tested for 10 times, and the average value is taken as the hardness of the area. The results obtained are in accordance with example 1.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.