阅读说明：本技术 金属3d打印零件的激光表面改性方法 (Laser surface modification method for metal 3D printing part ) 是由 尹衍军 孙兵兵 李鹏飞 张峰 于 2019-09-20 设计创作，主要内容包括：本发明金属3D打印零件的激光表面改性方法,包括以下步骤S1、利用金属增材设备完成零件的制备；S2、根据零件表面粗糙度要求以及成形工艺不同判断是否需要进行表面机加工处理；若符合,则进行步骤S3；S3、对零件表面进行清洁处理；S4、对零件表面进行喷砂处理,去除表面未熔合的金属粉末颗粒及去除支撑而留下来的毛刺；S5、采用喷雾方式将复合吸收材料粉末喷在步骤S4处理后的零件表面,形成激光吸收层；S6、使用激光器对步骤S5处理后的金属增材成形零件进行激光辐照,形成激光熔凝层。本发明克服了现有金属增材零件表面质量差、表面质量不均匀的问题,能够使零件近表面的微孔洞和微缺陷消除。(The laser surface modification method of the metal 3D printing part comprises the following steps of S1, completing the preparation of the part by using metal additive equipment; s2, judging whether surface machining is needed or not according to the surface roughness requirement of the part and different forming processes; if yes, go to step S3; s3, cleaning the surface of the part; s4, performing sand blasting treatment on the surface of the part, and removing unfused metal powder particles on the surface and burrs left by support; s5, spraying composite absorbing material powder on the surface of the part processed in the step S4 in a spraying mode to form a laser absorption layer; and S6, performing laser irradiation on the metal additive forming part processed in the step S5 by using a laser to form a laser fused layer. The invention overcomes the problems of poor surface quality and uneven surface quality of the existing metal additive part and can eliminate the micro-holes and micro-defects on the near surface of the part.)

1. The laser surface modification method of the metal 3D printing part is characterized by comprising the following steps:

s1, preparing the parts by using metal additive equipment;

s2, judging whether surface machining is needed or not according to the surface roughness requirement of the part and different forming processes; if yes, go to step S3;

s3, cleaning the surface of the part;

s4, performing sand blasting treatment on the surface of the part, and removing unfused metal powder particles on the surface and burrs left by support;

s5, spraying composite absorbing material powder on the surface of the part processed in the step S4 in a spraying mode to form a laser absorption layer;

and S6, performing laser irradiation on the metal additive forming part processed in the step S5 by using a laser to form a laser fused layer.

2. The laser surface modification method of a metal 3D printed part according to claim 1, characterized in that: in the step S4, the metal additive forming part needs to be separated from the substrate by wire cutting, the support is removed by using a tool if necessary, and if the surface requirement of the part is qualified, the surface is not subjected to sand blasting by using a sand blasting method.

3. The laser surface modification method of a metal 3D printed part according to claim 1, characterized in that: in the step S5, different laser powers, laser spot sizes, and scanning speeds are selected according to different metal materials.

4. The laser surface modification method of a metal 3D printed part according to claim 1, characterized in that: the thickness of the laser fused layer in the step S5 is about 0.8mm-1.6mm, and no crack or defect exists.

5. The laser surface modification method of a metal 3D printed part according to claim 1, characterized in that: the thickness of the part surface in the step S5 is 0.3mm-0.5 mm.

Technical Field

The invention relates to the technical field of metal materials, in particular to a laser surface modification method for a metal 3D printing part.

Background

In the field of metal 3D printing, metal powder is rapidly heated by a heat source and then rapidly cooled in the 3D printing process, and a part generates a unique organization structure by a layer-by-layer processing mode from a point to a line to a surface.

In the actual printing process, the rapid heating and cooling can generate great participation stress in the material. In addition, due to the characteristics of the 3D printing process, micro-holes inevitably occur inside. These defects in the texture greatly reduce the useful life or range of use of the metal 3D printed part.

The additive forming part and the surface treatment process of the part are carried out by various processes such as surface sand blasting, hot isostatic pressing, laser surface impact strengthening and the like in order to prolong the service life of the metal 3D printing part. The document of the related application is, for example, a chinese patent with application number 201410315813.X, the surface of the additive manufacturing metal is polished by performing multiple scanning treatments on the additive manufacturing metal additional surface by using millisecond pulse laser and nanosecond pulse laser, the laser polishing method can change the surface stress state of the additive manufacturing metal part, the tensile stress is converted into the compressive stress, the polishing production efficiency can be improved, the laser polishing is 20 times of that of manual polishing, but the method has limited effects on improving and eliminating the micro-holes on the surface. The chinese patent application No. 201910403931.9 proposes a method of preparing a wear-resistant coating on the surface of a metal block by using a pre-sprayed mixed powder, and finally performing surface strengthening treatment by using a friction stir welding method, wherein although friction stir processing and spraying processes are relatively simple processes, the processing methods can be effectively used only for some parts with regular geometric shapes, and uniform strengthening of all surfaces of the parts is difficult to achieve if the geometric surfaces of the parts are complicated.

Disclosure of Invention

The invention aims to provide a laser surface modification method for a metal 3D printing part.

The invention realizes the purpose through the following technical scheme: a laser surface modification method for a metal 3D printing part comprises the following steps:

s1, preparing the parts by using metal additive equipment;

s2, judging whether surface machining is needed or not according to the surface roughness requirement of the part and different forming processes; if yes, go to step S3;

s3, cleaning the surface of the part;

s4, performing sand blasting treatment on the surface of the part, removing unfused metal powder particles on the surface and removing burrs left by support;

s5, spraying composite absorbing material powder on the surface of the part processed in the step S4 in a spraying mode to form a laser absorbing layer;

and S6, performing laser irradiation on the metal additive forming part processed in the step S5 by using a laser to form a laser fused layer.

Further, in the step S4, the metal additive-formed part needs to be separated from the substrate by wire cutting, the support is removed by using a tool if necessary, and if the surface of the part is required to be qualified, the surface is not subjected to sand blasting in a sand blasting manner.

Further, in step S5, different laser powers, laser spot sizes, and scanning speeds are selected according to different metal materials.

Further, the thickness of the laser fused layer in the step S5 is about 0.8mm to 1.6mm, and no crack or defect exists.

Further, the thickness of the surface of the part in the step S5 is 0.3mm-0.5 mm.

Compared with the prior art, the laser surface modification method for the metal 3D printing part has the beneficial effects that: the problems of poor surface quality and uneven surface quality of the existing metal additive part are solved, and micro-holes and micro-defects on the near-surface of the part can be eliminated.

Detailed Description

The laser surface modification method of the metal 3D printing part comprises the following steps:

s1, preparing the parts by using metal additive equipment;

s2, judging whether surface machining is needed or not according to the surface roughness requirement of the part and different forming processes; if yes, go to step S3;

s3, cleaning the surface of the part;

s4, performing sand blasting treatment on the surface of the part, removing unfused metal powder particles on the surface and removing burrs left by support; specifically, the metal additive forming part needs to be separated from the substrate by wire cutting, the support is removed by using a tool when necessary, and if the surface requirement of the part is qualified, the surface is not subjected to sand blasting treatment by using a sand blasting mode.

S5, spraying composite absorbing material powder on the surface of the part processed in the step S4 in a spraying mode to form a laser absorbing layer; specifically, different laser powers, laser spot sizes and scanning speeds are selected according to different metal materials. If the material is stainless steel, the laser power is 1900W-2300W, the spot width is 10mm, and the scanning speed is 4-8 mm/s; when the material is titanium-aluminum alloy, the laser power is 300W-400W, the spot width is 2mm, and the scanning speed is 0.5-1 mm/s. The thickness of the laser fused layer is about 0.8mm-1.6mm, and the laser fused layer has no crack and no defect. The thickness of the surface of the part is 0.3mm-0.5 mm.

And S6, performing laser irradiation on the metal additive forming part processed in the step S5 by using a laser to form a laser fusing layer, specifically, selecting different preheating temperatures and preheating times according to different materials.

The invention overcomes the problems of poor surface quality and uneven surface quality of the existing metal additive part and can eliminate the micro-holes and micro-defects on the near surface of the part. By adopting the spraying method, a uniform absorption layer can be obtained on the surface of the part, so that the laser absorption layer can better interact with the laser and the substrate, stable energy input is provided, and a uniform fused layer is obtained. The tissue morphology of the obtained fused layer is correspondingly changed, and defects such as pores, poor surface quality and the like of the fused layer are obviously controlled and the mechanical property is enhanced. The corrosion resistance and wear resistance are improved due to the improvement of surface defects.

The surface laser melting process of the invention does not generally add any metal element, and the melting layer and the material matrix form metallurgical bonding.

Aiming at the inevitable defects of tiny holes, air holes and the like in the metal additive forming part, in the laser melting process, because the surface metal is melted, the gas which is not discharged because of high cooling speed or violent flow of a molten pool in the printing process can escape in the melting process.

The invention remelting the surface of metal additive forming part, and re-crystallizing the surface metal during remelting to obtain uniform and fine equiaxed crystal on the surface of part. The surface layer obtained by quenching and recrystallization is homogeneous and has higher hardness, wear resistance and corrosion resistance.

The laser remelting of the surface of the metal additive forming part has the advantages of thin melting layer, small heat action, little influence on the surface roughness and the workpiece size, and direct use without subsequent polishing.

The surface of the metal additive forming part related by the invention is subjected to laser remelting, the solid solubility limit of solute atoms in a matrix is improved, grains and second phase particles are ultra-fine, a metastable phase is formed, and a single crystal structure without diffusion and even an amorphous state can be obtained, so that the generated novel alloy has excellent performance which cannot be obtained by the traditional method.

While there have been shown and described what are at present considered the fundamental principles of the invention and its essential features and advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.