A new type of laser cladding high wear-resistant self-lubricating high chromium iron-based alloy and preparation method

Abstract

The present invention discloses a novel laser cladding high wear-resistant and self-lubricating high chromium iron-based alloy and a preparation method thereof. The method mainly forms a novel composite alloy powder by adding optimized contents of WS2 and Ti powder to the gas atomized 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder. Under the optimized laser cladding process parameters, the composite alloy powder has excellent laser formability, and the microstructure mainly consists of fine-grained martensite M, austenite A, alloy carbide M7C3, M 23 C6 and in-situ generated TiS self-lubricating phase and the like. The average hardness of the alloy sample reaches 666HV 0.2 , and the friction coefficient reaches 0.3 under the high-temperature friction condition of 400°C. The synergistic effect of the multiphase wear-resistant microstructure and the TiS solid lubricating phase enables the prepared alloy sample to have good high-temperature wear resistance and self-lubricating performance, and has important application prospects in the field of laser additive manufacturing and remanufacturing of parts under the high-temperature service conditions in the metallurgical industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and specifically relates to a laser-clad highly wear-resistant self-lubricating high-chromium iron-based new alloy and a preparation method thereof. Background Art

[0002] my country is a major iron and steel metallurgical producer. In the steel rolling or heat treatment industry, rollers (furnace bottom rollers) are key components of hot rolling, continuous casting, heat treatment and other process transmission equipment. They are in direct contact with the steel billets on the production line. Their use characteristics directly affect the output of rolling or heat treatment and the quality of steel, which not only affects the production cost, but also determines the stability of the entire production process. Because these parts are generally affected by complex factors such as high temperature (400-900℃), friction, wear, corrosion, fatigue, oxidation, etc. under the complex working conditions of "heat-force-flow", their service life is often short and they need to be constantly replaced or repaired and remanufactured to meet production needs. The market economy is about 10 billion yuan. In response to this demand, people mainly use surface strengthening technology for remanufacturing to extend the service life.

[0003] Laser cladding technology is an advanced green manufacturing process. Since its alloy preparation process is characterized by non-equilibrium metallurgy, the alloy strengthening layer prepared by it often has the characteristics of special organizational structure and metallurgical combination of strengthening layer interface, which makes the strengthening layer show high wear resistance, corrosion resistance, fatigue resistance, oxidation resistance and other high performance. It has achieved fruitful results in the field of surface remanufacturing of key parts in the fields of metallurgy, petrochemical, aerospace, transportation, etc., and has obtained huge economic, environmental and social benefits.

[0004] However, there are still deficiencies and difficulties in the laser repair and remanufacturing engineering technology for these key parts in the metallurgical industry. The main reasons are: (1) The parts have harsh service conditions and the dynamic damage behavior and failure mechanism of the components are complex under the coupling of heat, force and flow fields, resulting in the lack of design criteria for the composition of high-quality and efficient remanufacturing strengthening layer alloy materials; (2) The existing commercial alloy powders cannot meet the needs of high-performance repair and remanufacturing technology under complex and harsh working conditions, and there is a lack of high-performance special alloy powders; (3) The strength and toughness matching of the repair and remanufacturing strengthening layer is poor, the crack defects caused by the cladding structure and stress are difficult to eliminate, and the fatigue performance cannot meet the requirements; (4) The large stress and deformation in the laser cladding engineering of large-size parts are the key technical bottlenecks that restrict the engineering application of high-performance strengthening layers. Therefore, focusing on the urgent need for advanced remanufacturing technology in the metallurgical industry and the above-mentioned scientific and technological bottlenecks that still exist in laser cladding remanufacturing, further research on high-wear-resistant and self-lubricating alloys and preparation methods for laser cladding of parts surfaces that meet the complex working conditions of "heat, force and flow" not only has important scientific research significance, but also has broad practical application prospects. Although there have been studies on high wear-resistant and self-lubricating laser cladding technology in China, there have been no reports on research and patents on laser cladding of high-wear-resistant self-lubricating alloys and preparation methods for parts in service under high-temperature and complex "heat-force-flow" service conditions in the metallurgical industry. Summary of the invention

[0005] In order to overcome the defects of the above-mentioned prior art, the present invention is guided by the idea of ​​studying and preparing alloys with high wear resistance and self-lubricating properties. On the basis of preparing high chromium iron-based wear-resistant alloy powder, WS is added. 2 Ti powder is added to form a new composite powder, which is processed by laser non-equilibrium metallurgy process WS 2 The reaction between laser cladding and Ti can generate TiS solid lubricating phase with high-temperature self-lubrication in situ in the cladding alloy, forming a synergistic match between multiphase wear-resistant and self-lubricating structures. A new type of laser cladding high-wear-resistant and self-lubricating high-chromium iron-based alloy and its preparation method have been studied, providing an important reference for the application and development of manufacturing and remanufacturing technology of related parts in the metallurgical industry.

[0006] In order to achieve the above-mentioned invention object, the present invention provides a laser cladding high wear-resistant self-lubricating high chromium iron-based new alloy and a preparation method thereof, wherein the preparation method comprises the following steps:

[0007] ①Preparation of 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder by vacuum induction atomization;

[0008] ② Preparation of new high-chromium iron-based composite alloy powder: by adding optimized content of WS to the 20CrNiMoBSi high-chromium iron-based wear-resistant alloy powder prepared by gas atomization 2 +Ti powder, and then mixed powder treatment in ball mill;

[0009] ③ Substrate pretreatment: after the treatment, 1mm high chromium iron-based composite alloy powder is pre-paved on the substrate;

[0010] ④ The laser cladding process is used to prepare a highly wear-resistant, self-lubricating high-chromium iron-based alloy coating by two layers of cladding.

[0011] In the above technical scheme, further, in step ①, the chemical composition mass percentage of the 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder is C: 0.18-0.20%, Cr: 16.80-17.00%, Ni: 1.5-2.0%, Mo: 1.9-2.1%, B: 1.1-1.2%, Si: 0.8-0.9%, and the balance is Fe.

[0012] Firstly, 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder was prepared by gas atomization. The iron-based alloy samples prepared under optimized laser cladding process parameters had no crack or porosity defects, good laser formability and high hardness.

[0013] Furthermore, the sphericity of the 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder in step ① is 98%, the fluidity is 16g / 50g, and the bulk density is 4.56g / cm 3 , particle size is 10~150μm.

[0014] Furthermore, in step ②, the WS 2 and Ti powder in a mass ratio of 5:2. After mixing, WS 2 The mass of +Ti powder accounts for 5-11wt.% of the high chromium iron-based wear-resistant alloy powder.

[0015] Furthermore, the ball mill mixing powder processing method in step ② is: putting the configured iron-based composite alloy powder into a mixing bottle equipped with steel balls, with a ball-to-material ratio of 3:1, and then putting it on a roller ball mill to mix for 8 hours, and then putting it in a drying oven for drying for standby use; the process parameters of the roller ball mill are: speed 360r / min, power 370W, and input voltage 220V.

[0016] Furthermore, the substrate pre-treated in step ③ is made of Q235 steel with a size of 200 mm×100 mm×10 mm. Before the experiment, the surface of the Q235 steel needs to be pre-treated, the surface of the substrate needs to be polished flat, and then alcohol is used to remove impurities and oil stains.

[0017] Furthermore, the laser cladding equipment in step ④ is a semiconductor laser, and its spot size is 4×4 mm 2 ; Laser energy density is 138J / cm 3The specific parameters are: laser power (P) is 2200W, defocus is 304mm, scanning speed (V) is 4mm / s, pre-paved powder layer thickness (t) is 1mm, scanning spacing (d) is 2.4mm, overlap rate is 40%, scanning mode is unidirectional scanning, and argon protection is used.

[0018] After the first layer of wear-resistant self-lubricating high-chromium iron-based alloy layer is cooled, 1 mm of high-chromium iron-based composite alloy powder is pre-paved on the surface of the first layer of alloy layer; then the second layer of wear-resistant self-lubricating high-chromium iron-based alloy layer is prepared using the laser process parameters described in step ④; the final alloy layer thickness is about 1.8 mm.

[0019] The new composite alloy sample prepared under the optimized laser cladding process parameters has no crack pore defects, has good laser formability, and has a high wear-resistant structure and in-situ self-lubrication matching relationship. The cladding alloy structure is mainly composed of fine-grained martensite (M), austenite (A), alloy carbide M 7 C 3 、M 23 C 6 The average hardness of the alloy sample prepared by optimizing the parameters reached 666HV. 0.2 The friction coefficient at 400℃ is 0.3. The synergistic effect of multiphase wear-resistant structure and TiS solid lubricating phase makes the alloy sample have good high-temperature wear resistance and self-lubricating properties. 2 The alloy prepared by forming a new composite alloy powder with Ti has further improved hardness and friction performance. The alloy and preparation method of the invention have important application prospects in the field of laser additive manufacturing and remanufacturing of parts under high-temperature service conditions in the metallurgical industry.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] ① The high chromium iron-based wear-resistant self-lubricating new alloy prepared by the present invention has a new composition, and the average hardness of the optimized alloy sample reaches 666HV 0.2 The friction coefficient reaches 0.3 at 400°C, which has both good wear resistance and self-lubricating properties.

[0022] ② The present invention adds WS in the gas atomization preparation of 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder. 2 With Ti powder, WS 2 Reacts with Ti powder in the laser molten pool, Ti replaces WS 2 The S in the alloy forms the lubricating phase TiS, and the in-situ generated lubricating phase TiS makes the composite alloy have high-temperature self-lubricating properties.

[0023] ③ The high chromium iron-based new alloy prepared by the laser cladding process of the present invention mainly consists of fine-grained martensite (M), austenite (A), alloy carbide M 7 C 3 、M 23 C 6 It is composed of TiS self-lubricating phase and has the characteristics of multiphase synergistic organization of wear-resistant phase and self-lubricating phase.

[0024] ④ The highly wear-resistant and self-lubricating high-chromium iron-based composite alloy powder designed in the present invention is suitable for laser additive manufacturing and remanufacturing of key parts in metallurgical high-temperature (400-800°C) service conditions, and provides useful theoretical and technical references for the design of laser cladding components with both high wear resistance and in-situ self-lubrication matching and the preparation of high-performance parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 SEM photos of the powders used in the present invention: (a) 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder, (b) high chromium iron-based composite alloy powder (WS 2 +Ti powder accounts for 9wt.% of the mixed powder, and the remainder is high chromium iron-based alloy powder);

[0026] Figure 2 It is a schematic diagram of the laser cladding process of the present invention;

[0027] Figure 3 The sample was prepared from the 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder used in Example 1, and the laser energy density was 138 J / mm 3 Metallographic photographs;

[0028] Figure 4 This is the XRD diagram of the laser cladding Fe-based alloy in Example 1;

[0029] Figure 5 This is a SEM photo of the laser cladding iron-based alloy sample of Example 1;

[0030] Figure 6 This is the surface scanning spectrum result of the laser cladding iron-based alloy sample in Example 1;

[0031] Figure 7 This is a hardness curve of the laser cladding iron-based alloy sample in Example 1 (the measurement direction of microhardness is perpendicular to the laser scanning direction, and the measurement is made from the cladding layer to the inside of the substrate);

[0032] Figure 8 The friction and wear test results of the iron-based alloy sample prepared in Example 1 under high temperature friction conditions of 400°C;

[0033] Fig. 9This is a laser confocal photograph of the friction and wear surface of the laser cladding iron-based alloy sample of Example 1 under high temperature friction conditions of 400°C;

[0034] Fig.10 This is a SEM photograph of the friction and wear surface of the laser cladding iron-based alloy sample of Example 1 under high temperature friction conditions of 400°C;

[0035] Fig.11 For Example 2, a sample (WS 2 +Ti powder accounts for 5wt.% of the mixed powder, and the balance is high chromium iron-based alloy powder), and the laser energy density is 138J / mm 3 Metallographic photographs at that time;

[0036] Fig.12 This is the XRD diagram of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 2;

[0037] Fig.13 This is a SEM photo of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 2;

[0038] Fig.14 This is the surface scanning energy spectrum result of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample in Example 2;

[0039] Fig.15 This is a hardness curve of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample in Example 2 (the measurement direction of microhardness is perpendicular to the laser scanning direction, and the measurement is made from the cladding layer to the inside of the substrate);

[0040] Fig.16 The friction and wear test results of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy under high-temperature friction conditions of 400°C in Example 2;

[0041] Fig.17 This is a laser confocal photograph of the friction and wear surface of the laser-clad wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 2 under high-temperature friction conditions of 400°C;

[0042] Fig.18 This is a SEM photograph of the friction and wear surface of the laser-clad wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 2 under high-temperature friction conditions of 400°C;

[0043] Fig.19 For Example 3, a sample (WS 2 +Ti powder accounts for 11wt.% of the mixed powder mass percentage, and the balance is high chromium iron-based alloy powder), and the laser energy density is 138J / mm 3 Metallographic photographs at that time;

[0044] Fig. 20 This is the XRD diagram of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 3;

[0045] Fig.21 This is a SEM photo of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 3;

[0046] Fig. 22 This is the surface scanning energy spectrum result of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample in Example 3;

[0047] Fig.23 This is a hardness curve of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample in Example 3 (the measurement direction of microhardness is perpendicular to the laser scanning direction, and the measurement is made from the cladding layer to the inside of the substrate);

[0048] Fig.24 The friction and wear test results of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy under high-temperature friction conditions of 400°C in Example 3;

[0049] Fig.25 This is a laser confocal photograph of the friction and wear surface of the laser-clad wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 3 under high-temperature friction conditions of 400°C;

[0050] Fig.26 This is a SEM photograph of the friction and wear surface of the laser-clad wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 3 under high-temperature friction conditions of 400°C;

[0051] Fig. 27 For Example 4, a sample (WS 2 +Ti powder accounts for 9wt.% of the mixed powder, and the balance is high chromium iron-based alloy powder), and the laser energy density is 138J / mm 3 Metallographic photographs at that time;

[0052] Fig.28 This is the XRD diagram of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 4;

[0053] Fig.29 This is a SEM photo of the laser-clad wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 4;

[0054] Fig.30 This is the surface scanning energy spectrum result of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample in Example 4;

[0055] Fig.31 This is a hardness curve of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample in Example 4 (the measurement direction of microhardness is perpendicular to the laser scanning direction, and the measurement is made from the cladding layer to the inside of the substrate);

[0056] Fig.32 The friction and wear test results of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy in Example 4 under high-temperature friction conditions of 400°C;

[0057] Fig.33 This is a laser confocal photograph of the friction and wear surface of the laser-clad wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 4 under high-temperature friction conditions of 400°C;

[0058] Fig.34 This is a SEM photograph of the friction and wear surface of the laser-clad wear-resistant self-lubricating high-chromium iron-based alloy sample of Example 4 under high-temperature friction conditions of 400°C;

[0059] Fig.35 This is a histogram of the wear of samples of Examples 1, 2, 3, and 4 of the present invention under high-temperature friction conditions of 400°C. DETAILED DESCRIPTION

[0060] The present invention is further described below in conjunction with specific examples, but the present invention is not limited in any way. To avoid redundant description, the raw materials in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified. Figure 2 shown.

[0061] Example 1

[0062] A laser cladding high wear-resistant self-lubricating high chromium iron-based new alloy and a preparation method thereof, the preparation method comprising the following steps:

[0063] ① Preparation of 20CrNiMoBSi high chromium iron-based alloy powder by gas atomization. The chemical composition of the obtained 20CrNiMoBSi high chromium iron-based alloy powder is C: 0.18%, Cr: 17.0%, Ni: 1.8%, Mo: 2.0%, B: 1.1%, Si: 0.9%, and the balance is Fe; the SEM photo of the alloy powder is as follows Figure 1 As shown in (a), the characteristics are that the sphericity reaches 98%, the fluidity is 16g / 50g, and the bulk density is 4.56g / cm 3 , the main particle size is 10~150μm.

[0064] ② Substrate pretreatment. The substrate is made of Q235 steel with a size of 200mm×100mm×10mm. The surface of Q235 steel needs to be pretreated before the experiment. The surface of the substrate is polished flat, and then alcohol is used to remove impurities and oil stains. 1mm high-chromium iron-based alloy powder is pre-paved on the substrate.

[0065] ③ The high chromium iron-based alloy coating was prepared by laser cladding process. The equipment used for laser cladding was FL-Dlight02-3000 W semiconductor laser (spot size was 4×4 mm 2 ). When the laser energy density is 138J / mm 3 Printing was carried out under the laser process parameters, where the laser power (P) was 2200 W, the defocus was 304 mm, the scanning speed (V) was 4 mm / s, the pre-laid powder layer thickness (t) was 1 mm, the scanning spacing (d) was 2.4 mm (the overlap rate was 40%), the scanning mode was unidirectional scanning, and argon protection was used.

[0066] ④ The second layer of high chromium iron-based alloy coating is prepared by laser cladding process. After the first layer of high chromium iron-based alloy coating is cooled, 1mm iron-based alloy powder is prefabricated on the surface of the first layer of coating to increase the thickness of the wear-resistant coating. The second layer of high chromium iron-based alloy coating is prepared by the process parameters of step ③. The final coating thickness is about 1.8mm.

[0067] The microstructure and properties of the samples prepared under this process are mainly as follows: Figure 3 The metallographic photograph of the laser cladding iron-based alloy sample shows that the laser cladding sample has no crack or porosity defects and has good formability. Figure 4 The XRD analysis diagram shown, Figure 5 The SEM images and Figure 6 The surface scanning spectrum results shown in the figure show that the laser cladding iron-based alloy structure is mainly composed of fine-grained martensite (M), austenite (A), alloy carbide M 7 C 3 、M 23 C 6 The average hardness of the tested samples is 622HV 0.2 ,like Figure 7 The hardness curve of the laser cladding iron-based alloy sample is shown in the figure. The friction coefficient is 0.69 ( Figure 8 ),like Fig. 9 Laser confocal photographs of the friction and wear surfaces shown Fig.10 The SEM photo of the friction and wear surface shows that the wear loss is 17.42 mg ( Fig.35 ).

[0068] Example 2

[0069] A laser cladding high wear-resistant self-lubricating high chromium iron-based new alloy and preparation method, the main difference from Example 1 is that 5wt.% WS is added in the gas atomization preparation of 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder 2Form a new composite alloy powder with Ti powder; laser cladding to prepare a new alloy with high wear-resistant structure and in-situ self-lubricating phase. The preparation method includes the following steps:

[0070] Step 1: Prepare 20CrNiMoBSi high chromium iron-based alloy powder by gas atomization. The chemical composition of the obtained 20CrNiMoBSi high chromium iron-based alloy powder is C: 0.2%, Cr: 16.8%, Ni: 1.5%, Mo: 1.9%, B: 1.2%, Si: 0.8%, and the balance is Fe. It is characterized by a sphericity of 98%, a fluidity of 16g / 50g, and a bulk density of 4.56g / cm 3 , the main particle size is 10~150μm.

[0071] Step 2: Preparation of high chromium iron-based composite alloy powder. Add WS to the 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder prepared by gas atomization. 2 +Ti powder. Self-lubricating particles WS 2 The mass ratio of WS and Ti powder according to the reaction equation 2 :Ti=5:2, and then add 5wt.% of mass percentage to high chromium iron-based wear-resistant alloy powder to form a composite powder. The prepared powder needs to be put into a mixing bottle equipped with steel balls, with a ball-to-material ratio of 3:1. After tightening the bottle cap, wrap it with insulating tape, and then put it on a roller ball mill to mix for 8 hours, and then put it in a drying oven for drying. The process parameters of the roller ball mill are: speed 360r / min, power 370W, input voltage 220V.

[0072] Step 3: Substrate pretreatment. The substrate is made of Q235 steel with a size of 200mm×100mm×10mm. The surface of Q235 steel needs to be pretreated before the experiment. The surface of the substrate is polished and smoothed, and then alcohol is used to remove impurities and oil stains. 1mm high-chromium iron-based composite alloy powder is pre-paved on the substrate.

[0073] Step 4: Use laser cladding process to prepare wear-resistant self-lubricating high-chromium iron-based alloy coating. The equipment used for laser cladding is FL-Dlight02-3000 W semiconductor laser (spot size is 4×4mm 2 ). When the laser energy density is 138J / mm 3 Printing was carried out under the laser process parameters, where the laser power (P) was 2200 W, the defocus was 304 mm, the scanning speed (V) was 4 mm / s, the pre-laid powder layer thickness (t) was 1 mm, the scanning spacing (d) was 2.4 mm (the overlap rate was 40%), the scanning mode was unidirectional scanning, and argon protection was used.

[0074] Step 5: Prepare the second layer of wear-resistant self-lubricating high-chromium iron-based alloy coating by laser cladding process. After the first layer of wear-resistant self-lubricating high-chromium iron-based alloy coating is cooled, pre-lay 1mm of high-chromium iron-based composite alloy powder on the surface of the first layer of coating to increase the thickness of the wear-resistant self-lubricating coating. Prepare the wear-resistant self-lubricating high-chromium iron-based alloy coating by using the process parameters of step 4. The final coating thickness is about 1.8mm.

[0075] The microstructure and properties of the samples prepared under this process are mainly as follows: Fig.11 The metallographic photograph of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample shown in the figure shows that the laser cladding sample has no cracks or pores, and the composite alloy powder has excellent laser formability under the optimized laser cladding process parameters. Fig.12 The XRD analysis diagram shown, Fig.13 The SEM images and Fig.14 The surface scanning spectrum results shown in the figure show that the laser cladding wear-resistant self-lubricating high chromium iron-based alloy structure is mainly composed of fine-grained martensite (M), austenite (A), alloy carbide M 7 C 3 、M 23 C 6 The composition is the same as that of the in-situ generated TiS self-lubricating alloy, wherein the content of TiS is 2.0wt.%. The average hardness of the alloy sample is 618HV. 0.2 ,like Fig.15 The hardness curve of the laser cladding wear-resistant self-lubricating high chromium iron-based alloy sample is shown in the figure. The friction coefficient is 0.54 ( Fig.16 ),like Fig.17 Laser confocal photographs of the friction and wear surfaces shown Fig.18 The SEM photo of the friction and wear surface shows that the wear loss is 9.42 mg ( Fig.35 ).

[0076] Example 3

[0077] A laser cladding high wear-resistant self-lubricating high chromium iron-based new alloy and preparation method, the main difference from Example 1 is that 11wt.% WS is added in the gas atomization preparation of 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder 2 Form a new composite alloy powder with Ti powder; laser cladding to prepare a new alloy with high wear-resistant structure and in-situ self-lubricating phase. The preparation method includes the following steps:

[0078] Step 1: Prepare 20CrNiMoBSi high chromium iron-based alloy powder by gas atomization. The chemical composition of the obtained 20CrNiMoBSi high chromium iron-based alloy powder is C: 0.19%, Cr: 16.9%, Ni: 2.0%, Mo: 2.1%, B: 1.1%, Si: 0.9%, and the balance is Fe. It is characterized by a sphericity of 98%, a fluidity of 16g / 50g, and a bulk density of 4.56g / cm 3 , the main particle size is 10~150μm.

[0079] Step 2: Preparation of high chromium iron-based composite alloy powder. Add WS to the 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder prepared by gas atomization. 2 +Ti powder. Self-lubricating particles WS 2 The mass ratio of WS and Ti powder according to the reaction equation 2 :Ti=5:2, and then add 11wt.% of mass percentage to high chromium iron-based wear-resistant alloy powder to form a composite powder. The prepared powder needs to be put into a mixing bottle equipped with steel balls, with a ball-to-material ratio of 3:1. After tightening the bottle cap, wrap it with insulating tape, and then put it on a roller ball mill to mix for 8 hours, and then put it in a drying oven for drying. The process parameters of the roller ball mill are: speed 360r / min, power 370W, input voltage 220V.

[0080] Step 3: Substrate pretreatment. The substrate is made of Q235 steel with a size of 200mm×100mm×10mm. The surface of Q235 steel needs to be pretreated before the experiment. The surface of the substrate is polished and smoothed, and then alcohol is used to remove impurities and oil stains. 1mm high-chromium iron-based composite alloy powder is pre-paved on the substrate.

[0081] Step 4: Use laser cladding process to prepare wear-resistant self-lubricating high-chromium iron-based alloy coating. The equipment used for laser cladding is FL-Dlight02-3000 W semiconductor laser (spot size is 4×4mm 2 ). When the laser energy density is 138J / mm 3 Printing was carried out under the laser process parameters, where the laser power (P) was 2200 W, the defocus was 304 mm, the scanning speed (V) was 4 mm / s, the pre-laid powder layer thickness (t) was 1 mm, the scanning spacing (d) was 2.4 mm (the overlap rate was 40%), the scanning mode was unidirectional scanning, and argon protection was used.

[0082] Step 5: Prepare the second layer of wear-resistant self-lubricating high-chromium iron-based alloy coating by laser cladding process. After the first layer of wear-resistant self-lubricating high-chromium iron-based alloy coating is cooled, pre-lay 1mm of high-chromium iron-based composite alloy powder on the surface of the first layer of coating to increase the thickness of the wear-resistant self-lubricating coating. Prepare the wear-resistant self-lubricating high-chromium iron-based alloy coating by using the process parameters of step 4. The final coating thickness is about 1.8mm.

[0083] The microstructure and properties of the samples prepared under this process are mainly as follows: Fig.19 The metallographic photograph of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample shown in the figure shows that the laser cladding sample has no cracks or pores, and the composite alloy powder has excellent laser formability under the optimized laser cladding process parameters. Fig. 20 The XRD analysis diagram shown, Fig.21 The SEM images and Fig. 22 The surface scanning spectrum results shown in the figure show that the laser cladding wear-resistant self-lubricating high chromium iron-based alloy structure is mainly composed of fine-grained martensite (M), austenite (A), alloy carbide M 7 C 3 、M 23 C 6 The composition is the same as that of the in-situ generated TiS self-lubricating alloy, wherein the content of TiS is 4.6wt.%. The average hardness of the alloy sample after testing reaches 604HV 0.2 ,like Fig.23 The hardness curve of the laser cladding wear-resistant self-lubricating high chromium iron-based alloy sample is shown in the figure. The friction coefficient is 0.55 ( Fig.24 ),like Fig.25 Laser confocal photographs of the friction and wear surfaces shown Fig.26 The SEM photo of the friction and wear surface shows that the wear loss is 11.34 mg ( Fig.35 ).

[0084] Example 4

[0085] A laser cladding high wear-resistant self-lubricating high chromium iron-based new alloy and preparation method, the main difference from Example 1 is that 9wt.% WS is added in the gas atomization preparation of 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder 2 Form a new composite alloy powder with Ti powder; laser cladding to prepare a new alloy with high wear-resistant structure and in-situ self-lubricating phase. The preparation method includes the following steps:

[0086] Step 1: Prepare 20CrNiMoBSi high chromium iron-based alloy powder by gas atomization. The chemical composition of the obtained 20CrNiMoBSi high chromium iron-based alloy powder is C: 0.19%, Cr: 16.8%, Ni: 1.8%, Mo: 2.0%, B: 1.1%, Si: 0.9%, and the balance is Fe. It is characterized by a sphericity of 98%, a fluidity of 16g / 50g, and a bulk density of 4.56g / cm 3 , the main particle size is 10~150μm.

[0087] Step 2: Preparation of high chromium iron-based composite alloy powder. Add WS to the 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder prepared by gas atomization. 2 +Ti powder. Self-lubricating particles WS 2 The mass ratio of WS and Ti powder according to the reaction equation 2 The powder is prepared in a ratio of 5:2, and then added to the high chromium iron-based wear-resistant alloy powder according to a mass percentage of 9wt.% to form a composite powder. The prepared powder needs to be placed in a mixing bottle equipped with steel balls, with a ball-to-material ratio of 3:1, and the bottle cap is tightened and wrapped with insulating tape, and then placed on a roller ball mill for mixing for 8 hours, and then placed in a drying oven for drying. Figure 1 (b) is high chromium iron-based composite alloy powder (WS 2 +Ti powder accounts for 9wt.% of the mixed powder mass percentage, and the balance is high chromium iron-based alloy powder. The process parameters of the roller ball mill are: speed 360r / min, power 370W, input voltage 220V.

[0088] Step 3: Substrate pretreatment. The substrate is made of Q235 steel with a size of 200mm×100mm×10mm. The surface of Q235 steel needs to be pretreated before the experiment. The surface of the substrate is polished and smoothed, and then alcohol is used to remove impurities and oil stains. 1mm high-chromium iron-based composite alloy powder is pre-paved on the substrate.

[0089] Step 4: Use laser cladding process to prepare wear-resistant self-lubricating high-chromium iron-based alloy coating. The equipment used for laser cladding is FL-Dlight02-3000 W semiconductor laser (spot size is 4×4mm 2 ). When the laser energy density is 138J / mm 3 Printing was carried out under the laser process parameters, where the laser power (P) was 2200 W, the defocus was 304 mm, the scanning speed (V) was 4 mm / s, the pre-laid powder layer thickness (t) was 1 mm, the scanning spacing (d) was 2.4 mm (the overlap rate was 40%), the scanning mode was unidirectional scanning, and argon protection was used.

[0090] Step 5: Prepare the second layer of wear-resistant self-lubricating high-chromium iron-based alloy coating by laser cladding process. After the first layer of wear-resistant self-lubricating high-chromium iron-based alloy coating is cooled, pre-lay 1mm of high-chromium iron-based composite alloy powder on the surface of the first layer of coating to increase the thickness of the wear-resistant self-lubricating coating. Prepare the wear-resistant self-lubricating high-chromium iron-based alloy coating by using the process parameters of step 4. The final coating thickness is about 1.8mm.

[0091] The microstructure and properties of the samples prepared under this process are mainly as follows: Fig. 27 The metallographic photograph of the laser cladding wear-resistant self-lubricating high-chromium iron-based alloy sample shown in the figure shows that the laser cladding sample has no cracks or pores, and the composite alloy powder has excellent laser formability under the optimized laser cladding process parameters. Fig.28 The XRD analysis diagram shown, Fig.29 The SEM images and Fig.30 The surface scanning spectrum results shown in the figure show that the laser cladding wear-resistant self-lubricating high chromium iron-based alloy structure is mainly composed of fine-grained martensite (M), austenite (A), alloy carbide M 7 C 3 、M 23 C 6 The composition is the same as that of the in-situ generated TiS self-lubricating alloy, wherein the content of TiS is 3.3wt.%. The average hardness of the alloy sample after testing reaches 666HV 0.2 ,like Fig.31 The hardness curve of the laser cladding wear-resistant self-lubricating high chromium iron-based alloy sample is shown in the figure. The friction coefficient is 0.3 ( Fig.32 ),like Fig.33 Laser confocal photographs of the friction and wear surfaces shown Fig.34 The SEM photo of the friction and wear surface shows that the wear amount is 7.92 mg ( Fig.35 ).

[0092] Therefore, according to Fig.35 The wear bar graphs of Example 1, Example 2, Example 3, and Example 4 under 400°C high temperature friction conditions show that the wear of Example 1 laser cladding iron-based alloy is 17.42 mg, and the wear of Example 2 laser cladding wear-resistant self-lubricating high chromium iron-based alloy (5wt.%) is 9.42 mg, and the wear is reduced by 46%. The wear of Example 3 laser cladding wear-resistant self-lubricating high chromium iron-based alloy (11wt.%) is 11.34 mg, and the wear is reduced by 35%. The wear of Example 4 laser cladding wear-resistant self-lubricating high chromium iron-based alloy (9wt.%) is 7.92 mg, and the wear is reduced by 55%. That is, the 9wt.% WS 2+Ti composite alloy powder laser cladding alloy sample has the best wear resistance, the lowest friction coefficient under 400℃ high temperature friction conditions, and the best high temperature wear resistance and self-lubricating properties, providing a new method for laser cladding preparation of metallurgical "heat-force-flow" working condition friction parts.

[0093] For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a new type of high-wear-resistant self-lubricating high-chromium iron-based alloy by laser cladding, characterized in that: The preparation method comprises the following steps: ①Preparation of 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder by vacuum induction atomization; The chemical composition of the 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder is C: 0.18% to 0.20%, Cr: 16.80% to 17.00%, Ni: 1.5% to 1.8%, Mo: 1.9% to 2.1%, B: 1.1% to 1.2%, Si: 0.8% to 0.9%, and the balance is Fe; ② Preparation of high chromium iron-based composite alloy powder: Add WS2+Ti powder to the 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder prepared by gas atomization, and then mix the powder in a ball mill; WS2 and Ti powders are mixed in a mass ratio of 5:2, and after mixing, the mass of WS2+Ti powder accounts for 5-11wt.% of the high chromium iron-based wear-resistant alloy powder; ③ Pretreatment of the substrate, after which 1 mm of the high chromium iron-based composite alloy powder is pre-paved on the substrate; ④ Using laser cladding technology, two layers of cladding are used to prepare highly wear-resistant, self-lubricating high-chromium iron-based alloy coatings; The high wear-resistant self-lubricating high chromium iron-based new alloy prepared by the above method has a structure mainly composed of fine-grained martensite, austenite, alloy carbides M7C3, M 23 The alloy consists of C6 and TiS self-lubricating phases; the content of TiS in the alloy structure is 2.0-4.6wt.%; the average hardness of the alloy sample reaches 666HV 0.2 , the friction coefficient at 400℃ reaches 0.3, and the multiphase wear-resistant structure and TiS solid lubrication phase work synergistically; The TiS self-lubricating phase is in-situ generated by metallurgical reaction of WS2 and Ti powder in a laser molten pool.

2. The preparation method according to claim 1, characterized in that: Step ① The sphericity of the 20CrNiMoBSi high chromium iron-based wear-resistant alloy powder reaches 98%, the fluidity is 16s / 50g, and the bulk density is 4.56g / cm 3 , particle size is 10~150μm.

3. The preparation method according to claim 1, characterized in that: Step ② The ball mill powder mixing treatment method is: put the configured iron-based composite alloy powder into a mixing bottle equipped with steel balls, with a ball-to-material ratio of 3:1, and then put it on a roller ball mill for mixing for 8 hours, and then put it in a drying oven for drying for use; the process parameters of the roller ball mill are: speed 360r / min, power 370W, input voltage 220V.

4. The preparation method according to claim 1, characterized in that: Step ④ The laser cladding equipment is a semiconductor laser with a spot size of 4×4mm 2 ; Laser energy density is 138J / cm 3 , overlap rate is 40%, scanning mode is unidirectional scanning, and argon gas protection is used.

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