CN110878413A - High-hardness iron-based powder for ultra-high-speed laser cladding and preparation method thereof - Google Patents

Abstract

The invention discloses high-hardness iron-based powder for ultrahigh-speed laser cladding, which consists of the following components in percentage by mass: 0.6-1.0% of C powder, 3-7% of Cr powder, 4-8% of Mo powder, 4-8% of W powder, 1-3% of V powder, 0.5-1.5% of Si powder, and CeO₂0.4-0.8% of powder and the balance of Fe. The preparation method comprises the following steps: mixing C powder, Cr powder, Mo powder, W powder, V powder,Silicon iron and CeO₂Mixing the powders, vacuum melting, and pulverizing by gas atomization method, wherein N is used₂The atomizing pressure is 6MPa as atomizing gas, and the superheat degree of the melt is kept between 100 and 150 ℃ in the atomizing process. Then screening out a certain size, and carrying out vacuum packaging to obtain the product. The laser cladding layer obtained by the high-hardness iron-based powder for ultrahigh-speed laser cladding has excellent hardness; when the high-hardness iron-based powder for ultrahigh-speed laser cladding is used for laser cladding, the material utilization rate is high, and the cost is low.

Description

High-hardness iron-based powder for ultra-high-speed laser cladding and preparation method thereof

technical field

The invention belongs to the technical field of metal materials, in particular to a high-hardness iron-based powder for ultra-high-speed laser cladding, and relates to a preparation method for the high-hardness iron-based powder for ultra-high-speed laser cladding.

Background technique

Laser cladding is a surface modification technology. It adds a cladding material on the surface of the substrate, and uses a high-energy density laser beam to fuse it with the thin layer on the surface of the substrate, forming a metallurgical metallurgy on the surface of the substrate. combined cladding.

The ultra-high-speed laser cladding technology changes the relative position of the laser spot and the powder spot, and uses a laser with a small spot and high power density to make the powder melt or semi-melt on the molten pool. cladding layer. Compared with traditional laser cladding, when cladding thin coatings, the cladding line speed and rate are greatly improved, the cladding layer has good finish and high hardness, and has a wide range of applications in the field of shaft parts repair or surface modification to replace electroplating. application space.

Compared with ordinary laser cladding technology, ultra-high-speed laser cladding has small spot density and large cladding line speed, which makes the cladding layer in an extremely hot and cold state, resulting in large residual stress in the cladding layer. As the hardness of the cladding layer increases, the brittleness of the cladding layer increases, resulting in the cladding layer being easily cracked. The cracking problem of high-hardness and high-wear-resistant cladding layer limits the popularization and application of ultra-high-speed laser cladding, especially to replace the electroplating technology that pollutes the environment seriously.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a high-hardness iron-based powder for ultra-high-speed laser cladding, and a reasonable composition ratio enables the cladding layer to form iron with good toughness and high hardness under the condition of rapid heating and rapid cooling of ultra-high-speed laser cladding Base cladding layer, which can replace electroplating when thin layer cladding.

The second object of the present invention is to provide a preparation method of high-hardness iron-based powder for ultra-high-speed laser cladding.

The technical scheme adopted in the present invention is that a high-hardness iron-based powder for ultra-high-speed laser cladding is composed of the following raw material components according to mass percentage: C powder 0.6-1.0%, Cr powder 3-7%, Mo powder 4% ~8%, W powder 4~8%, V powder 1~3%, Si powder 0.5~1.5%, CeO ₂ powder 0.4~0.8%, the balance is Fe, and the sum of the weight percentages of the above components is 100%.

The present invention is also characterized in that,

The purity of the alloy powder of each raw material component is all ≥99%.

The second technical solution adopted by the present invention is a preparation method of high-hardness iron-based powder for ultra-high-speed laser cladding, and the specific steps are as follows:

Step 1: Weigh out C powder 0.6-1.0%, Cr powder 3-7%, Mo powder 4-8%, W powder 4-8%, V powder 1-3%, Si powder 0.5-1.5% by mass percentage , CeO ₂ powder is 0.4-0.8%, the balance is Fe, and the sum of the weight percentages of the above components is 100%;

Step 2: Mix the raw material alloy powders in Step 1, vacuum smelting, and use the gas atomization method to make powder;

Step 3: Perform particle size sieving on the atomized alloy powder, so that the sieved alloy powder is within a certain particle size range.

Step 4: The prepared powder is vacuum-packed for use.

The present invention is also characterized in that,

In step 2, vacuum smelting equipment is used, N ₂ is used as the atomizing gas, the atomizing pressure is 6 MPa, and the degree of superheat of the melt is maintained between 100 and 150° C. during the atomizing process.

In step 3, the particle size range of the sieved alloy powder is 25-53 μm, that is, 270-500 mesh.

The fluidity requirement of the sieved alloy powder is 25-40s/100g.

The beneficial effects of the present invention are:

(1) The present invention proposes a preparation method of high-hardness iron-based powder for ultra-high-speed laser cladding, and designs iron-based high-hardness powder for ultra-high-speed laser cladding process.

(2) The reasonable composition ratio in the method of the present invention enables the cladding layer to form an iron-based cladding layer with good toughness and high hardness under the condition of fast heating and rapid cooling by ultra-high-speed laser cladding, which can be replaced in thin-layer cladding plating.

(3) In the method of the present invention, the particle size of the powder is selected to be 25-53 μm (270-500 mesh). When the powder particle size is large, its fluidity is good, but it is difficult to melt, and it is easy to block the powder feeding nozzle; when the powder particle size is small, the fluidity is poor, and it is easily disturbed by the protective gas and splashes on the protective lens. After comprehensive tests, the present invention selects powder with a particle size of 25-53 μm.

(4) In the method of the present invention, by designing a reasonable composition ratio and cooperating with the characteristics of rapid heating and rapid cooling of ultra-high-speed laser cladding, the structure of the obtained cladding layer is mainly martensite, and different types of carbides are formed in situ reinforced particle phase. By adding more strong carbide forming elements Mo, W, and V to the powder, high melting point carbides are formed. These high melting point carbides act as nucleating agents to promote the spheroidization of carbides. In addition, different elements generate different types of carbides in situ in the cladding layer. Under extremely cold conditions, the carbides exist in the form of fine and dispersed, which is beneficial to improve the hardness and wear resistance of the cladding layer material.

Description of drawings

Fig. 1 is the low magnification metallographic structure and morphology of the cladding layer obtained when the high-hardness iron-based powder for high-speed laser cladding prepared in Example 2 of the present invention performs laser cladding on 45 steel;

FIG. 2 is a metallographic morphology diagram of the cladding layer, the 45 steel, and the cladding layer obtained when the high-hardness iron-based powder for high-speed laser cladding prepared in Example 2 of the present invention is laser clad on 45 steel.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention provides a high-hardness iron-based powder for ultra-high-speed laser cladding, which is composed of the following raw material components by mass percentage: C powder 0.6-1.0%, Cr powder 3-7%, Mo powder 4-8%, W Powder 4-8%, V powder 1-3%, Si powder 0.5-1.5%, CeO ₂ powder 0.4-0.8%, the balance is Fe, and the sum of the weight percentages of the above components is 100%.

As mentioned above, the purity of the alloy powder of each raw material component is all ≥99%.

The roles and functions of the main alloy components in the iron-based powder are as follows:

CeO ₂ rare earth element can purify grain boundaries, improve carbide distribution, and can also be used as a nucleating agent to refine grains.

Si element can improve the wettability between the iron-based cladding metal and the substrate, which is beneficial to the formation of the cladding layer. However, the Si content should not be too high, otherwise a hard phase of Si will be formed, which will significantly reduce the toughness of the cladding layer.

Cr element can react with C to form hard compounds such as Cr ₂₃ C ₆ and Cr ₇ C ₃ , which can improve the hardness and wear resistance of the cladding metal;

Mo, W, and V elements can form high-melting carbides in the cladding layer. These high-melting carbides act as nucleating agents to promote the spheroidization of carbides.

The present invention also provides a method for preparing the above-mentioned high-hardness iron-based powder for ultra-high-speed laser cladding. The specific steps are as follows:

Step 1: Weigh out C powder 0.6-1.0%, Cr powder 3-7%, Mo powder 4-8%, W powder 4-8%, V powder 1-3%, Si powder 0.5-1.5% by mass percentage , CeO ₂ powder is 0.4-0.8%, the balance is Fe, and the sum of the weight percentages of the above components is 100%;

Step 2: After the above-mentioned raw materials are fully mixed, vacuum melting equipment is used, _N2 is used as the atomization gas, the atomization pressure is 6MPa, and the superheat degree of the melt is maintained between 100 and 150°C during the atomization process.

Step 3: Perform particle size screening on the atomized alloy powder, and screen metal powder with a particle size range of 25-53 μm (270-500 mesh), and the fluidity of the powder is required to be 25-40s/100g.

Step 4: The prepared powder is vacuum-packed for use.

Example 1

Step 1: Weigh out C powder 0.6%, Cr powder 3%, Mo powder 4%, W powder 4%, V powder 1%, Si powder 0.5%, CeO ₂ powder 0.4% by mass percentage, and the balance is Fe, The sum of the weight percentages of the above components is 100%.

Step 2: After fully mixing the above raw materials, vacuum melting equipment is used, _N2 is used as the atomizing gas, the atomization pressure is 6MPa, and the superheat degree of the melt is maintained at 100°C during the atomization process.

Step 3: Perform particle size screening on the atomized alloy powder, screen metal powder with a particle size of 25 μm, and the fluidity of the powder is required to be 25s/100g.

Step 4: The prepared powder is vacuum-packed for use.

The ultra-high-speed laser cladding was performed on the 45 steel substrate with the high-hardness iron-based powder for ultra-high-speed laser cladding prepared in Example 1, and the specific steps were as follows:

(1) Machining the surface of the substrate and removing surface stains with alcohol or acetone;

(2) Preheating the prepared powder, the preheating temperature is 120°C, the preheating time is 1 hour, sieved (-270 mesh ~ +500 mesh) and then loaded into the powder feeder;

(3) Adjust the relative position of the equipment and the workpiece, and set the cladding path;

(4) Use flame heating to preheat the area of the base material that has just begun to clad, and the preheating temperature is 200°C to 300°C to reduce the temperature gradient in this area and reduce the cracking susceptibility;

(5) Laser cladding, set the laser cladding power to 6kW, the laser spot diameter of 3mm, the powder feeding speed of 100g/min, and the cladding layer overlap rate of 85%; the protective gas is argon, and the cladding line speed is 50m/min. After cladding, wrap the final cladding area with thermal insulation cotton to achieve slow cooling of the cladding layer and avoid cracks.

After testing, the Rockwell hardness of the cladding metal is 52HRC.

Example 2

Step 1: Weigh out C powder 1.0%, Cr powder 7%, Mo powder 8%, W powder 8%, V powder 3%, Si powder 1.5%, CeO ₂ powder 0.8% by mass percentage, and the balance is Fe, The sum of the weight percentages of the above components is 100%;

Step 2: After fully mixing the above raw materials, vacuum melting equipment is used, _N2 is used as the atomization gas, the atomization pressure is 6MPa, and the superheat degree of the melt is maintained at 150°C during the atomization process.

Step 3: Perform particle size screening on the atomized alloy powder, and screen metal powder with a particle size of 53 μm, and the fluidity of the powder is required to be 40s/100g.

Step 4: The prepared powder is vacuum-packed for use.

The ultra-high-speed laser cladding was performed on the 45 steel substrate with the high-hardness iron-based powder for ultra-high-speed laser cladding prepared in Example 1, and the specific steps were as follows:

(1) Machining the surface of the substrate and removing surface stains with alcohol or acetone;

(2) Preheating the prepared powder, the preheating temperature is 120°C, the preheating time is 1 hour, sieved (-270 mesh ~ +500 mesh) and then loaded into the powder feeder;

(3) Adjust the relative position of the equipment and the workpiece, and set the cladding path;

(4) Use flame heating to preheat the area of the base material that has just begun to clad, and the preheating temperature is 200°C to 300°C to reduce the temperature gradient in this area and reduce the cracking susceptibility;

(5) Laser cladding, set the laser cladding power to 6kW, the laser spot diameter of 3mm, the powder feeding speed of 100g/min, and the cladding layer overlap rate of 85%; the protective gas is argon, and the cladding line speed is 50m/min. After cladding, wrap the final cladding area with thermal insulation cotton to achieve slow cooling of the cladding layer and avoid cracks.

After testing, the Rockwell hardness of the cladding metal is 63HRC.

The high-hardness iron-based powder for ultra-high-speed laser cladding prepared in Example 2 was clad on 45 steel. The low-magnification metallographic structure of the weld of the cladding layer is shown in Figure 1, and Figure 2 is the cladding layer and 45 steel. Matrix metallographic structure. It can be seen from the metallographic pictures that the cladding layer and the 45 steel substrate are separated by a fusion line, the fusion line is clear, and no common defects such as cracks and pores are found near the fusion line. The cladding layer is mainly composed of cellular dendrites. The crystals are smaller.

Example 3

Step 1: Weigh out C powder 0.7%, Cr powder 4%, Mo powder 5%, W powder 5%, V powder 2%, Si powder 0.8%, CeO ₂ powder 0.5% by mass percentage, and the balance is Fe, The sum of the weight percentages of the above components is 100%;

Step 2: After fully mixing the above raw materials, vacuum melting equipment is used, _N2 is used as the atomization gas, the atomization pressure is 6MPa, and the superheat degree of the melt is maintained at 120°C during the atomization process.

Step 3: Perform particle size screening on the atomized alloy powder, screen metal powder with a particle size of 30 μm, and the fluidity of the powder is required to be 30s/100g.

Step 4: The prepared powder is vacuum-packed for use.

The ultra-high-speed laser cladding was performed on the 45 steel substrate with the high-hardness iron-based powder for ultra-high-speed laser cladding prepared in Example 3, and the specific steps were as follows:

(1) Machining the surface of the substrate and removing surface stains with alcohol or acetone;

(2) Preheating the prepared powder, the preheating temperature is 120°C, the preheating time is 1 hour, sieved (-270 mesh ~ +500 mesh) and then loaded into the powder feeder;

(3) Adjust the relative position of the equipment and the workpiece, and set the cladding path;

(4) Use flame heating to preheat the area of the base material that has just begun to clad, and the preheating temperature is 200°C to 300°C to reduce the temperature gradient in this area and reduce the cracking susceptibility;

(5) Laser cladding, set the laser cladding power to 6kW, the laser spot diameter of 3mm, the powder feeding speed of 100g/min, and the cladding layer overlap rate of 85%; the protective gas is argon, and the cladding line speed is 50m/min. After cladding, wrap the final cladding area with thermal insulation cotton to achieve slow cooling of the cladding layer and avoid cracks.

After testing, the Rockwell hardness of the cladding metal is 55HRC.

Example 4

Step 1: Weigh out C powder 0.8%, Cr powder 5%, Mo powder 6%, W powder 6%, V powder 2.5%, Si powder 1.0%, CeO ₂ powder 0.6% by mass percentage, and the balance is Fe, The sum of the weight percentages of the above components is 100%;

Step 2: After fully mixing the above raw materials, vacuum melting equipment is used, _N2 is used as the atomizing gas, the atomization pressure is 6MPa, and the superheat degree of the melt is maintained at 110°C during the atomization process.

Step 3: Perform particle size screening on the atomized alloy powder, screen metal powder with a particle size of 52 μm, and the fluidity of the powder is required to be 25s/100g.

Step 4: The prepared powder is vacuum-packed for use.

The ultra-high-speed laser cladding was performed on the 45 steel substrate with the high-hardness iron-based powder for ultra-high-speed laser cladding prepared in Example 4, and the specific steps were as follows:

(1) Machining the surface of the substrate and removing surface stains with alcohol or acetone;

(2) Preheating the prepared powder, the preheating temperature is 120°C, the preheating time is 1 hour, sieved (-270 mesh ~ +500 mesh) and then loaded into the powder feeder;

(3) Adjust the relative position of the equipment and the workpiece, and set the cladding path;

(4) Use flame heating to preheat the area of the base material that has just begun to clad, and the preheating temperature is 200°C to 300°C to reduce the temperature gradient in this area and reduce the cracking susceptibility;

(5) Laser cladding, set the laser cladding power to 6kW, the laser spot diameter of 3mm, the powder feeding speed of 100g/min, and the cladding layer overlap rate of 85%; the protective gas is argon, and the cladding line speed is 50m/min. After cladding, wrap the final cladding area with thermal insulation cotton to achieve slow cooling of the cladding layer and avoid cracks.

After testing, the Rockwell hardness of the cladding metal is 57HRC.

Example 5

Step 1: Weigh out C powder 0.9%, Cr powder 6%, Mo powder 7%, W powder ₇ %, V powder 2.8%, Si powder 1.3%, CeO powder 0.7% by mass percentage, and the balance is Fe, The sum of the weight percentages of the above components is 100%;

Step 2: After fully mixing the above raw materials, vacuum melting equipment is used, _N2 is used as the atomizing gas, the atomization pressure is 6MPa, and the superheat degree of the melt is maintained at 100°C during the atomization process.

Step 3: Perform particle size screening on the atomized alloy powder, screen metal powder with a particle size of 33 μm, and the fluidity of the powder is required to be 35s/100g.

Step 4: The prepared powder is vacuum-packed for use.

The ultra-high-speed laser cladding was performed on the 45 steel substrate with the high-hardness iron-based powder for ultra-high-speed laser cladding prepared in Example 5, and the specific steps were as follows:

(1) Machining the surface of the substrate and removing surface stains with alcohol or acetone;

(2) Preheating the prepared powder, the preheating temperature is 120°C, the preheating time is 1 hour, sieved (-270 mesh ~ +500 mesh) and then loaded into the powder feeder;

(3) Adjust the relative position of the equipment and the workpiece, and set the cladding path;

(4) Use flame heating to preheat the area of the base material that has just begun to clad, and the preheating temperature is 200°C to 300°C to reduce the temperature gradient in this area and reduce the cracking susceptibility;

(5) Laser cladding, set the laser cladding power to 6kW, the laser spot diameter of 3mm, the powder feeding speed of 100g/min, and the cladding layer overlap rate of 85%; the protective gas is argon, and the cladding line speed is 50m/min. After cladding, wrap the final cladding area with thermal insulation cotton to achieve slow cooling of the cladding layer and avoid cracks.

After testing, the Rockwell hardness of the cladding metal is 59HRC.

The alloy powder is optimized to control the mass percentage of 1.0% C powder, 7% Cr powder, 8% Mo powder, 8% W powder, 3% V powder, 1.5% Si powder, 0.8% CeO ₂ powder, and the balance is Fe, high-speed laser cladding of 45 steel plate can be used to obtain a cladding layer with good forming effect, minimum defects and better mechanical properties.

Claims (6)

1. The high-hardness iron-based powder for ultrahigh-speed laser cladding is characterized by comprising the following raw material components in percentage by mass: 0.6-1.0% of C powder, 3-7% of Cr powder, 4-8% of Mo powder, 4-8% of W powder, 1-3% of V powder, 0.5-1.5% of Si powder, and CeO₂0.4-0.8% of powder and the balance of Fe, wherein the sum of the weight percentages of the components is 100%.

2. The high-hardness iron-based powder for high-speed laser cladding according to claim 1, wherein the purity of each raw material component alloy powder is not less than 99%.

3. A preparation method of high-hardness iron-based powder for ultrahigh-speed laser cladding is characterized by comprising the following specific steps:

step 1: respectively weighing 0.6-1.0% of C powder, 3-7% of Cr powder, 4-8% of Mo powder, 4-8% of W powder, 1-3% of V powder, 0.5-1.5% of Si powder, and CeO according to mass percentage₂0.4-0.8% of powder and the balance of Fe, wherein the sum of the weight percentages of the components is 100%;

step 2: mixing the raw material alloy powder obtained in the step 1, then carrying out vacuum melting, and adopting a gas atomization method to prepare powder;

and step 3: and (4) carrying out particle size screening on the atomized alloy powder to ensure that the screened alloy powder is in a certain particle size range.

And 4, step 4: and carrying out vacuum packaging on the prepared powder for later use.

4. The method for preparing a high-hardness iron-based powder for ultra-high speed laser cladding as claimed in claim 3, wherein in step 2, vacuum melting equipment is adopted, and N is used₂The atomizing pressure is 6MPa as atomizing gas, and the superheat degree of the melt is kept between 100 and 150 ℃ in the atomizing process.

5. The method for preparing a high-hardness iron-based powder for ultra-high speed laser cladding as claimed in claim 3, wherein in step 3, the particle size range of the sieved alloy powder is 25-53 μm, i.e. 270-500 mesh.

6. The method for preparing a high-hardness iron-based powder for ultra-high speed laser cladding as claimed in claim 5, wherein the fluidity requirement of the sieved alloy powder is 25-40 s/100 g.

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