CN105478763A - Laser forming method of TiC-Al-Gr composite material component - Google Patents

Abstract

The invention relates to a laser forming method of a TiC-Al-Gr composite material component. The selected raw material powder formula is: graphite 5.67~6.35wt.%, Ti? 40.54~44.43wt.%, mixed rare earth 0.47~0.67wt.%, Al balance. The quantitative delivery of powder in laser forming is completed by a multi-hopper delivery system. Laser forming uses a 3-tube coaxial laser head. Through the control of the powder delivery system and laser head, the internal and external gradient layered structure of TiC-Al-Gr components can be realized. , The fracture toughness of TiC-Al-Gr components can reach more than 60% of that of Al alloys.

Description

A Laser Forming Method for TiC-Al-Gr Composite Components

technical field

The invention belongs to the field of laser forming and relates to a laser forming method of a TiC-Al-Gr composite material component.

Background technique

TiC has a very high melting point, excellent high temperature strength, thermal stability, low density, high elastic modulus, high hardness and good wear resistance, and is widely used in the field of hard alloy materials such as cutting tools and molds.

TiC particle-reinforced Al-based composite materials have excellent properties such as high specific strength, high specific modulus, low density, low thermal expansion coefficient and good wear resistance, and are widely used in aerospace, precision instruments, automotive engines, sports equipment, electronic packaging, etc. There are important application prospects. Graphite (Gr) in Al-based composites can improve its wear resistance, and at the same time further improve the performance of the material such as shock resistance and energy absorption.

The preparation technology of MMC can be divided into in-situ self-generation and forced addition according to the different ways of adding reinforcing particles. The in-situ self-generation technology uses alloy design to react and nucleate in situ in the matrix metal to generate one or several thermodynamically stable reinforcement phases. This method avoids the decomposition of the external reinforcement, saves energy, resources and can reduce emissions. The reinforcement surface of the material is pollution-free, and the product performance is excellent. However, the process has strict requirements, is difficult to master, and the composition and volume fraction of the reinforcing phase are not easy to control.

The laser forming process uses the method of small-volume cumulative forming, which can control the uniform distribution of the reinforcing phase at a macroscopic level, and provides the possibility for powder-fed laser in-situ forming particle-reinforced MMC. Therefore, the present invention adopts an online continuous powder feeding laser in-situ compound forming method to prepare TiC-Al composite material parts, and realizes continuous controllable reinforcement phase distribution of the formed parts.

Contents of the invention

The technical problem to be solved by the present invention is to provide a laser forming method of a TiC-Al-Gr composite material part with controllable reinforcement phase distribution. Starting from the in-situ synthesis route and laser forming process, the present invention provides a new laser forming method for TiC-Al-Gr composite material structural parts, which can make the reinforcing phase evenly distributed in the composite material and realize TiC-Al with excellent performance -Laser forming of Gr composite parts.

The inventive method mainly comprises the following steps:

(1) Raw material formula and pretreatment

The raw material formula is: graphite 5.67~6.35wt.%, Ti40.54~44.43wt.%, mixed rare earth 0.47~0.67wt.%, Al balance, the raw material is in powder form, the size of metal powder and graphite powder is 60~200 microns ; Ball mill metal Cr powder and rare earth powder for 0.5-6 hours;

(2) Powder feeding and mixing

The multi-hopper spiral powder feeding mixing system is used for powder feeding and timely mixing. The multi-hopper screw powder feeding mixing system is composed of three powder feeders respectively connected to a common laser head through powder feeding pipes to mix Ti and rare earth powder Put in the first hopper, graphite powder in the second hopper, Al powder in the third hopper; three screw powder feeders feed powder at the same time, and control the proportion of powder by adjusting the screw speed;

(3) Laser forming

The laser head of the laser forming adopts 3 coaxial discontinuous nozzles to realize the enveloping powder injection to the laser molten pool, so that the components of the laser molten pool are evenly distributed; the digital graphics of the designed parts are sliced by layering software, and the laser The scanning path and its interlayer connection and coordination, set the thickness of each layer to 0.05~0.4mm, and then perform laser forming in layers on a four-axis digital processing machine tool; control the powder feeding composition and laser scanning route, so that the proportion of locally generated reinforcement phase TiC Gradient distribution, that is, the outer layer of the structural part is a wear-resistant TiC-Al-Gr composite material, and the inner layer is a metal matrix material, and the final raw materials meet the ratio requirements of step (1).

Step (3) Use fiber optic/CO ₂ laser, output power 100~3000W, spot diameter 0.2~4mm, overlap rate 10~80%, laser head Ar gas flow 0.5~13L/min, powder feeder Ar gas flow 0.5~ 12L/min, laser head scanning speed 3~125mm/s. The laser processing environment is an argon protective atmosphere, and the pressure is 1 atmosphere.

The multi-hopper screw powder feeding mixing system used in the present invention is composed of three powder feeders respectively connected to a common laser head through powder feeding pipes, as shown in FIG. 1 . The powder feeder is composed of a hopper, a screw and a fluidizer, and the screw is driven by a DC stepping motor.

The properties of TiC-Al-Gr composites depend on the content, size and uniform distribution of TiC. The present invention uses a three-hopper spiral powder feeding and mixing system to feed powder immediately, and uses a coaxial discontinuous laser head to form TiC-Al-Gr composite material parts, which realizes the distribution control of the reinforcement phase and eliminates the uneven distribution of TiC in the composite material In this case, the laser forming of TiC-Al-Gr composite structural parts with adjustable TiC content is realized.

The method of the present invention separately forms the surface layer and the inner layer of the component at the same time, controls the powder feeding composition and the laser scanning route, and realizes the laser manufacturing of the metal matrix composite material component with an internal and external layered structure, so that the inside of the component has the toughness of the metal material, and the surface layer has the toughness of the metal matrix composite material. It has the functions of grinding and high temperature oxidation resistance, and the overall fracture toughness of the parts is more than 60% of that of similar metal parts.

Description of drawings

Figure 1 Schematic diagram of the structure of the multi-hopper screw powder feeding mixing system.

detailed description

The present invention will be further described in conjunction with embodiments.

Embodiment one

A TiC-Al-Gr composite engine cylinder liner laser forming method, comprising the following processes:

(1) Raw material formula and pretreatment

The raw material formula is: graphite 5.67wt.%, Ti40.54wt.%, mixed rare earth 0.58wt.%, Al powder balance. The raw materials are in the form of powder, and the particle size of the metal powder and the graphite powder is 60 microns; the metal Cr powder and the rare earth powder are ball milled for 2 hours.

(2) Powder feeding and mixing

The powder feeding process is completed by a multi-hopper screw powder feeding mixing system. The Ti and rare earth mixed powder is put into the first hopper, the graphite powder is placed in the second hopper, and the Al powder is placed in the third hopper; 3 screws The powder feeder feeds powder at the same time, and adjusts the content of TiC in the forming part through the screw speed.

(3) Laser forming

The powder in the multi-hopper is air-carried to the laser head with 3 pipelines for laser forming. The laser head for laser forming uses 3 tubes of coaxial discontinuous nozzles to realize the powder injection around the laser melting pool, so that the laser melting The components of the pool are evenly distributed. Slicing the digital graphics data of the design parts using layering software, and establishing the best laser scanning path for layers and the connection between layers, setting the thickness of each layer to 0.25mm, and then performing laser layering on a four-axis digital processing machine tool Forming: control the powder feeding composition and laser scanning route, and carry out laser forming of the inner and outer layered structures of the composite parts, that is, the outer layer of the structural part is wear-resistant TiC-Al-Gr composite material, and the inner part is metal matrix material. Laser processing uses a fiber laser with an output power of 650W, a spot diameter of 0.4mm, an overlap rate of 50%, an Ar gas flow of the laser head of 6.8L/min, an Ar gas flow of the powder feeder of 5.5L/min, and a scanning speed of the laser head of 38mm/s. . The laser processing environment is an argon protective atmosphere, and the pressure is 1 atmosphere.

The inside of the formed part has the toughness of metal materials, and the surface layer has the functions of wear resistance and high temperature oxidation resistance, and the overall fracture toughness of the part is more than 60% of that of similar metal parts.

Embodiment two

A TiC-Al-Gr composite brake disc laser forming method, comprising the following processes:

(1) Raw material formula and pretreatment

The raw material formula is: graphite 6.35wt.%, Ti41.32wt.%, mixed rare earth 0.47wt.%, Al balance. The raw materials are in the form of powder, and the particle size of the metal powder and the graphite powder is 60 microns; the metal Cr powder and the rare earth powder are ball milled for 2.5 hours.

(2) Powder feeding and mixing

The powder feeding process is completed by a multi-hopper screw powder feeding mixing system. The Ti and rare earth mixed powder is put into the first hopper, the graphite powder is placed in the second hopper, and the Al powder is placed in the third hopper; 3 screws The powder feeder feeds powder at the same time, and adjusts the content of TiC in the forming part through the screw speed.

(3) Laser forming

The powder in the multi-hopper is air-carried to the laser head with 3 pipelines for laser forming. The laser head for laser forming uses 3 tubes of coaxial discontinuous nozzles to realize the powder injection around the laser melting pool, so that the laser melting The components of the pool are evenly distributed. Slicing the digital graphics data of the design parts using layering software, and establishing the best laser scanning path for layers and the connection between layers, setting the thickness of each layer to 0.26mm, and then performing laser layering on a four-axis digital processing machine tool Forming: control the powder feeding composition and laser scanning route, and carry out laser forming of the inner and outer layered structures of the composite parts, that is, the outer layer of the structural part is wear-resistant TiC-Al-Gr composite material, and the inner part is metal matrix material. Laser processing uses a fiber laser with an output power of 400W, a spot diameter of 0.35mm, an overlap rate of 60%, an Ar gas flow of the laser head of 4.2L/min, an Ar gas flow of the powder feeder of 6.8L/min, and a scanning speed of the laser head of 30mm/s. . The laser processing environment is an argon protective atmosphere, and the pressure is 1 atmosphere.

The inside of the formed part has the toughness of metal materials, and the surface layer has the functions of wear resistance and high temperature oxidation resistance, and the overall fracture toughness of the part is more than 60% of similar metal parts.

Embodiment Three

A TiC-Al-Gr composite bearing bush laser forming method, comprising the following processes:

(1) Raw material formula and pretreatment

The raw material formula is: graphite 6.13wt.%, Ti41.43wt.%, mixed rare earth 0.67wt.%, Al balance. The raw materials are in the form of powder, and the particle size of the metal powder and the graphite powder is 100 microns; the metal Cr powder and the rare earth powder are ball milled for 1.5 hours.

(2) Powder feeding and mixing

The powder feeding process is completed by a multi-hopper screw powder feeding mixing system. The Ti and rare earth mixed powder is put into the first hopper, the graphite powder is placed in the second hopper, and the Al powder is placed in the third hopper; 3 screws The powder feeder feeds powder at the same time, and adjusts the content of TiC in the forming part through the screw speed.

(3) Laser forming

The powder in the multi-hopper is air-carried to the laser head with 3 pipelines for laser forming. The laser head for laser forming uses 3 tubes of coaxial discontinuous nozzles to realize the powder injection around the laser melting pool, so that the laser melting The components of the pool are evenly distributed. Slicing the digital graphics data of the design parts using layering software, and establishing the best laser scanning path for layers and the connection between layers, setting the thickness of each layer to 0.18mm, and then performing laser layering on a four-axis digital processing machine tool Forming: control the powder feeding composition and laser scanning route, and carry out laser forming of the inner and outer layered structures of the composite parts, that is, the outer layer of the structural part is wear-resistant TiC-Al-Gr composite material, and the inner part is metal matrix material. Laser processing uses a fiber laser with an output power of 1000W, a spot diameter of 0.32mm, an overlap rate of 70%, an Ar gas flow rate of the laser head of 7.3L/min, an Ar gas flow rate of the powder feeder of 8.8L/min, and a scanning speed of the laser head of 10mm/s. . The laser processing environment is an argon protective atmosphere, and the pressure is 1 atmosphere.

Claims (3)

1. a laser forming method for TiC-Al-Gr composite element, is characterized in that comprising the steps:

(1) composition of raw materials and pretreatment

Composition of raw materials is: graphite 5.67 ~ 6.35wt.%, Ti40.54 ~ 44.43wt.%, mishmetal 0.47 ~ 0.67wt.%, Al surplus, and raw material adopts powder, metal dust and graphite powder size 60 ~ 200 microns; By Metal Cr powder and rare earth powder ball milling 0.5 ~ 6 hour;

(2) powder feeding and batch mixing

Many hoppers spiral powder feeding hybrid system is adopted to carry out powder feeding and mixing in time, described many hoppers spiral powder feeding hybrid system is connected to form respectively by powder feeding pipe and a common laser head by three powder feeders, Ti and rare earth mixed-powder are put into the 1st hopper, graphite powder is placed in the 2nd hopper, and Al powder is placed in the 3rd hopper; 3 screw rod powder feeder powder feedings simultaneously, and the ratio of powder is controlled by adjustment screw speed;

(3) laser forming

The laser head of laser forming adopts the coaxial discontinuous nozzle of 3 pipe, realizes encircling powder jetting to laser molten pool, makes each uniform composition distribution of laser molten pool; Utilize delamination software to cut into slices the digital figure of design part, and set up laser beam scan path and interlayer connection cooperation thereof, arranging every layer thickness is 0.05 ~ 0.4mm, then carries out laser forming at four number of axle word machining tool higher slices; Control powder feeding composition and laser scanning route, make the wild phase TiC ratio distribution gradient that local generates, namely structural member skin is wear-resisting TiC-Al-Gr composite, and inside is metal matrix material, and the raw material of final utilization meets the proportion requirement of step (1).

2. laser forming method according to claim 1, is characterized in that, in step (3), adopts optical fiber/CO ₂laser instrument, power output 100 ~ 3000W, spot diameter 0.2 ~ 4mm, overlapping rate 10 ~ 80%, laser head Ar throughput 0.2 ~ 12L/min, powder feeder Ar throughput 0.5 ~ 125L/min, laser head sweep speed 3 ~ 125mm/s.

3. laser forming method according to claim 1, is characterized in that, described powder feeder is made up of hopper, screw rod and Fluidizer, and screw rod is promoted by DC stepper motor.