阅读说明：本技术 一种增材制造铝合金强度及延伸率可控的热处理方法 (Heat treatment method for controlling strength and elongation of additive manufactured aluminum alloy ) 是由 祝弘滨 王敏卜 李瑞迪 刘昱 龚明 袁铁锤 牛朋达 于 2019-10-24 设计创作，主要内容包括：本发明提供一种增材制造铝合金强度及延伸率可控的热处理方法,包括：在180～475℃范围内,将所述增材制造铝合金进行固溶处理、时效处理或固溶-时效处理,其中所述增材制造铝合金为增材制造Al-Mg-Sc-Zr-Mn合金。本发明针对增材制造Al-Mg-Sc-Zr-Mn合金提供了不同的热处理条件以得到强度和延伸率不同的材料,实现了增材制造Al-Mg-Sc-Zr-Mn合金强度和延伸率的可控化,为其应用提供基础。本发明的热处理方法路径短,操作方便,可规模化生产。(The invention provides a heat treatment method for controlling strength and elongation of additive manufactured aluminum alloy, which comprises the following steps: and performing solution treatment, aging treatment or solution-aging treatment on the additive manufacturing aluminum alloy within the range of 180-475 ℃, wherein the additive manufacturing aluminum alloy is an additive manufacturing Al-Mg-Sc-Zr-Mn alloy. The invention provides different heat treatment conditions for additive manufacturing of the Al-Mg-Sc-Zr-Mn alloy so as to obtain materials with different strength and elongation, realizes the controllability of the strength and elongation of the additive manufacturing Al-Mg-Sc-Zr-Mn alloy, and provides a basis for the application of the alloy. The heat treatment method has short path and convenient operation, and can be used for large-scale production.)

1. A heat treatment method for controlling strength and elongation of additive manufactured aluminum alloy is characterized by comprising the following steps: and performing solution treatment, aging treatment or solution-aging treatment on the additive manufacturing aluminum alloy within the range of 180-475 ℃, wherein the additive manufacturing aluminum alloy is an additive manufacturing Al-Mg-Sc-Zr-Mn alloy.

2. The heat treatment process according to claim 1, characterized in that the solution-aging treatment comprises in particular: firstly, processing at 325-475 ℃ for 0.5-2 h, then cooling to 180-230 ℃ along with a furnace, preserving heat for 20-30 h, and then cooling to room temperature in air.

3. The heat treatment method of claim 2, wherein the microstructure of the additive manufactured aluminum alloy exhibits Al after the solution-aging treatment₃The (Sc, Zr) particles are dispersed and distributed, the melting pool boundary grain refining area is widened, and the intercrystalline brittle phase is reduced.

4. The heat treatment method according to claim 1, characterized in that the solution treatment specifically comprises: treating at 300-450 ℃ for 1-2 h, and then cooling to room temperature along with the furnace.

5. The heat treatment method of claim 4, wherein after the solution treatment, the microstructure of the additive manufactured aluminum alloy is characterized by a second phase solution and lattice distortion.

6. The heat treatment method according to claim 1, wherein the aging treatment specifically comprises: treating at 240-280 ℃ for 4-20 h, and then cooling to room temperature in air.

7. A heat treatment process as claimed in claim 6, wherein after said aging treatment the microstructure of said additive manufactured aluminium alloy is characterised by increased zones of fine grains, broadened pool boundaries and reduced average grain size.

8. The heat treatment method according to any one of claims 1 to 7, wherein the additive manufacturing Al-Mg-Sc-Zr-Mn alloy comprises the following raw material powder components in percentage by mass: 3.0 to 10.0 weight percent of Mg, 0.3 to 0.8 weight percent of Sc, 0.2 to 0.6 weight percent of Zrs, 0.3 to 1 weight percent of Mn, 0.01 to 3 weight percent of Si, 0.01 to 0.2 weight percent of Fe, 0.01 to 0.3 weight percent of Cu, 0.01 to 0.2 weight percent of Zns, 0.01 to 0.08 weight percent of Cr and the balance of Al;

and/or the forming process for manufacturing the Al-Mg-Sc-Zr-Mn alloy by the additive manufacturing method comprises the following steps: the laser 3D printing technology is adopted, the temperature of the substrate is 100-200 ℃, the laser power is 180-320W, the scanning speed is 300-800mm/s, the scanning interval is 0.08-0.12mm, and the interlayer thickness is 0.03-0.06 mm.

9. The thermal processing method of claim 8, wherein the microstructure of the additively manufactured Al-Mg-Sc-Zr-Mn alloy, prior to thermal processing, exhibits a mixed crystal structure in which fine equiaxed nano-scale crystals-coarse equiaxed micro-scale columnar crystals coexist.

10. The heat treatment method according to any one of claims 1 to 9, further comprising, before the heat treatment, sanding the surface of the additive manufactured aluminum alloy to be smooth using water abrasive paper;

preferably, the multiple layers of sanding are sequentially performed by using water-grinding sand paper with the model numbers of 320#, 600#, 1000#, 1500#, 2000#, wherein each layer is perpendicular to the sanding direction of the previous layer.

Technical Field

The invention relates to the field of aluminum alloy heat treatment, in particular to a heat treatment method with controllable strength and elongation rate for additive manufacturing of an aluminum alloy.

Background

The aluminum alloy has the advantages of low density, excellent mechanical property, good corrosion resistance, high weldability and the like, and is widely applied to the fields of automobile manufacturing, aerospace and rail transit. However, the conventional Al-Mg alloy belongs to non-heat treatment reinforced alloy, and the performance of the Al-Mg alloy cannot be further improved by a subsequent heat treatment process, so that the Sc and Zr composite microalloyed Al-Mg alloy is developed and widely applied to the fields of aerospace, rail transit and the like. The Russian and American space Bureau Lanli research center has used Al-Mg-Sc-Zr alloys for aerospace vehicle tanks, missile guidance tails, spacecraft structures and space stations. With the rapid development of industrial technology, the structural design of parts approaches to light weight, precision and complexity, and at this time, the deep development of material forming methods becomes an effective way to meet the requirement.

The laser additive manufacturing technology is used as a computer-aided rapid forming technology without a die, a complex precise structural part can be formed in a net mode, and based on the characteristic that the cooling speed of the technology is high, the formed alloy has the advantages of fine structure and excellent performance, and can be irreplaceable in preparation of aerospace and rail transit parts. The cooling speed in the laser additive manufacturing process is very high (105K/s), the alloy belongs to non-equilibrium solidification, the high-strength aluminum alloy manufactured by the additive manufacturing process is easy to generate a non-equilibrium eutectic phase T phase, and a small amount of Mn element is added in the Al-Mg-Sc-Zr alloy manufactured by the additive manufacturing process to generate Al₆The Mn intermetallic compound reduces the thermal cracking of impurity elements such as Fe and the like during solidification. Although Al₆Mn acts as a second phase strengthening particle with precipitation strengthening effect, but Al₆Mn is taken as a brittle intermetallic compound, the elongation of the alloy is reduced due to continuous distribution of Mn at grain boundaries, and the stress corrosion and electrochemical corrosion capability of the material are poor, so that the strength and the elongation of the additive manufacturing aluminum alloy need to be regulated and controlled through a heat treatment method.

At present, although the heat treatment processes of traditional aluminum alloys such as casting, rolling, extrusion, forging and the like are complete, the microstructure of the Al-Mg-Sc-Zr-Mn alloy manufactured by laser additive manufacturing is greatly different from the microstructure of the alloy manufactured by traditional casting and other methods, such as: the size distribution of the primary phase, the size distribution of the secondary phase, the grain size, the structure morphology and the like, so the existing heat treatment method is not suitable for the additive manufacturing of the Al-Mg-Sc-Zr-Mn alloy.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a heat treatment method for additive manufacturing of aluminum alloy with controllable strength and elongation.

A heat treatment method for controlling strength and elongation of additive manufactured aluminum alloy comprises the following steps: and performing solution treatment, aging treatment or solution-aging treatment on the additive manufacturing aluminum alloy within the range of 180-475 ℃, wherein the additive manufacturing aluminum alloy is an additive manufacturing Al-Mg-Sc-Zr-Mn alloy.

The Al-Mg-Sc-Zr-Mn alloy manufactured by additive manufacturing is easy to generate an unbalanced eutectic phase T phase, and the generated Al₆The continuous distribution of the Mn intermetallic compound at the grain boundary can reduce the elongation of the alloy and simultaneously lead to poor stress corrosion and electrochemical corrosion capability of the material. The research of the invention finds that the Al can be eliminated by carrying out the solution treatment at a proper temperature₆An intergranular continuous network of Mn and eutectic T phases promotes Al₆The recovery of the Mn intermetallic compound improves the elongation of the material; aging treatment is carried out at low temperature, so that precipitated particles are dispersed and separated out from the supersaturated solid solution, and the strength of the material is improved based on dispersion strengthening; higher temperature solution treatment combined with low temperature aging treatment for eliminating Al₆The Mn and T phases are enriched in the grain boundary and simultaneously ensure Al₃Sufficient precipitation of (Sc, Zr) particles and strengthening of precipitationThe service stability of the material under extreme conditions such as high temperature is improved. Therefore, according to the performance requirements of the target additive manufacturing aluminum alloy, namely the strength or the elongation percentage of the target additive manufacturing aluminum alloy, or both the strength and the elongation percentage, the heat treatment can be carried out by selecting proper conditions, so that the strength and the elongation percentage of the additive manufacturing aluminum alloy can be controlled.

Further, the solution-aging treatment specifically includes: firstly, processing at 325-475 ℃ for 0.5-2 h, then cooling to 180-230 ℃ along with a furnace, preserving heat for 20-30 h, and then cooling to room temperature in air.

In the technical scheme, the Al-Mg-Sc-Zr-Mn alloy manufactured by additive manufacturing is subjected to solid solution treatment at the temperature of 325-475 ℃ and then is subjected to aging treatment at the temperature of 180-230 ℃, so that Al can be eliminated₆Mn and T phases are enriched in grain boundaries, Al₃The (Sc, Zr) particles are fully separated out, the stability of the material in service under extreme conditions such as high temperature and the like is improved while precipitation strengthening is carried out, the scheme can give consideration to the strength and the elongation of the Al-Mg-Sc-Zr-Mn alloy manufactured by additive manufacturing, and the comprehensive performance is greatly improved.

Preferably, the solution-aging treatment specifically includes: setting the temperature rise speed of a vacuum annealing furnace to be 9-10 ℃/min, raising the temperature to 325-475 ℃, putting the additive manufacturing aluminum alloy into the vacuum annealing furnace, preserving the temperature for 0.5-2 h, then cooling the alloy along with the furnace for 1-2 h to 180-230 ℃, preserving the temperature for 20-30 h, taking out the additive manufacturing aluminum alloy within 10s, and cooling the alloy in the air to the room temperature.

Further, the microstructure of the additive manufactured aluminum alloy exhibits Al after the solution-aging treatment₃The (Sc, Zr) particles are dispersed and distributed, the melting pool boundary grain refining area is widened, and the intercrystalline brittle phase is reduced.

Further, the solution treatment specifically includes: treating at 300-450 ℃ for 1-2 h, and then cooling to room temperature along with the furnace.

In the technical scheme, the non-equilibrium eutectic phase T phase and Al phase in the solidification process are subjected to high-temperature short-time solid solution treatment₆The Mn phase is dissolved back, the intercrystalline continuous precipitate is destroyed, the resistance of the grain boundary to plastic deformation is improved in the deformation process, and the elongation is improved.

Preferably, the solution treatment specifically includes: setting the heating rate of the vacuum annealing furnace to be 7-15 ℃/min, heating to 300-450 ℃, then putting the material increase manufacturing aluminum alloy, preserving heat for 1-2 hours, and then cooling to room temperature along with the furnace.

Further, after the solution treatment, the microstructure of the additive manufactured aluminum alloy exhibits a second phase solution and lattice distortion characteristic.

Further, the aging treatment specifically includes: treating at 240-280 ℃ for 4-20 h, and then cooling to room temperature in air.

In the technical scheme, secondary Al is generated after long-time aging treatment at lower temperature₃The (Sc, Zr) particles are dispersed in the matrix, so that recrystallization can be effectively inhibited, and the alloy strength is improved by precipitation strengthening.

Preferably, the aging treatment specifically includes: setting the temperature rise speed of a vacuum annealing furnace to be 7-15 ℃/min, raising the temperature to 240-280 ℃, then placing the additive manufacturing aluminum alloy, preserving the heat for 4-20 h, then taking out the additive manufacturing aluminum alloy within 10s, and cooling the additive manufacturing aluminum alloy to the room temperature in the air.

Further, after the aging treatment, the microstructure of the additive manufactured aluminum alloy is characterized by increased fine crystalline regions, significantly broadened weld pool boundaries and reduced average grain size.

The room temperature mentioned in the invention is 5-30 ℃.

Furthermore, the heat treatment method is more suitable for additive manufacturing of the Al-Mg-Sc-Zr-Mn alloy, and the raw material powder components of the Al-Mg-Sc-Zr-Mn alloy comprise the following components in percentage by mass: 3.0 to 10.0 weight percent of Mg, 0.3 to 0.8 weight percent of Sc, 0.2 to 0.6 weight percent of Zr, 0.3 to 1 weight percent of Mn, 0.01 to 3 weight percent of Si, 0.01 to 0.2 weight percent of Fe, 0.01 to 0.3 weight percent of Cu, 0.01 to 0.2 weight percent of Zn, 0.01 to 0.08 weight percent of Cr and the balance of Al.

Further, the forming process for manufacturing the Al-Mg-Sc-Zr-Mn alloy in an additive mode comprises the following steps: the laser 3D printing technology is adopted, the temperature of the substrate is 100-200 ℃, the laser power is 180-320W, the scanning speed is 300-800mm/s, the scanning interval is 0.08-0.12mm, and the interlayer thickness is 0.03-0.06 mm.

Further, before heat treatment, the microstructure of the Al-Mg-Sc-Zr-Mn alloy prepared by the additive presents a mixed crystal structure with coexisting nano-scale fine equiaxed crystals, micron-scale coarse equiaxed crystals and micron-scale columnar crystals.

Further, the method comprises polishing the surface of the additive manufacturing aluminum alloy to be smooth by using water grinding sand paper before the heat treatment.

Further preferably, the multiple layers of sanding are sequentially performed by using water-milled sand paper with the models of 320#, 600#, 1000#, 1500#, and 2000#, wherein each layer is perpendicular to the sanding direction of the previous layer.

The invention provides different heat treatment conditions for additive manufacturing of the Al-Mg-Sc-Zr-Mn alloy so as to obtain materials with different strength and elongation, realizes the controllability of the strength and elongation of the additive manufacturing Al-Mg-Sc-Zr-Mn alloy, and provides a basis for the application of the alloy. The heat treatment method has short path and convenient operation, and can be used for large-scale production.

Drawings

FIG. 1 is a microstructure of an Al-Mg-Sc-Zr-Mn alloy according to example 1 of the present invention before heat treatment;

FIG. 2 is a microstructure diagram of an Al-Mg-Sc-Zr-Mn alloy subjected to solution treatment in additive manufacturing according to example 1 of the present invention;

FIG. 3 is a microstructure of an Al-Mg-Sc-Zr-Mn alloy that is additively manufactured according to example 1 of the present invention after aging treatment;

FIG. 4 is a microstructure of an Al-Mg-Sc-Zr-Mn alloy after solution-aging treatment in additive manufacturing according to example 1 of the present invention;

FIG. 5 is a stress-strain curve before and after heat treatment for additive manufacturing of Al-Mg-Sc-Zr-Mn alloy in example 1 of the present invention.

Detailed Description

The following examples are given to further illustrate the embodiments of the present invention. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.