A plasma surfacing flux-cored wire resistant to abrasive wear and a method of manufacturing the same

Abstract

The present application relates to a kind of anti-abrasion plasma surfacing flux-cored wire and its preparation method, including sheath and core;The core includes C:1.6%~3.8%, Si:0.4%~1.0%, Mn:0.4%~1.2%, B:2.10%~4.1%, Cr:15.0%~24.0%, Nb:4.1%~7.2%, W:4.3%~7.7%, La:0.1%~0.5%, the rest is Fe by weight percentage;The sheath is cold-rolled carbon steel strip.The advantage is: using the flux-cored wire to carry out plasma surfacing obtains the weld layer metal and presents high comprehensive mechanical property, hardness can reach HRC65 after surfacing 2~3mm, is used for the protection of the easily worn place of agricultural implement, greatly improves the service life of agricultural implement.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of welding materials, and particularly relates to a plasma surfacing flux-cored wire resistant to abrasive wear and a preparation method thereof. BACKGROUND

[0002] Severe working conditions make agricultural machines often contact with soil, sand, crop straw, root blocks and the like during field work, and are subjected to severe abrasive wear and a small amount of impact wear. The quality of agricultural machines directly affects the working efficiency and reliability of the whole machine.

[0003] In order to obtain agricultural machines with high wear resistance and long service life, most foreign high-end agricultural equipment manufacturers adopt surface engineering technology to prepare a wear-resistant layer containing hard phases on the cutting edge of agricultural machines. The surfacing green feed knife alloy layer produced by John Deere Company using surfacing technology has a hardness of HRC60-HRC65, and good results have been achieved in actual use. The green storage machine and green feed harvesting machine produced by Belotta, New Holland and Lely Storm adopt cladding technology to form a WC hard alloy layer on the cutting blade edge. The application provides a plasma surfacing flux-cored wire resistant to abrasive wear and a preparation method thereof. The flux-cored wire can be used to form an iron-based surfacing layer containing WC, NbC, Fe2B and the like on the surface of agricultural machines or parts with rapid wear, so that the surfacing layer has excellent abrasive wear resistance and certain resistance to low stress impact. SUMMARY

[0004] The application aims to provide a plasma surfacing flux-cored wire resistant to abrasive wear and a preparation method thereof, improve the wear resistance of the surfacing layer, and reduce the wear resistance of the surfacing layer due to micro-peeling when the formed plasma surfacing layer is subjected to external abrasive wear and rolling. The flux-cored wire can be used to form an iron-based surfacing layer containing WC, NbC, Fe2B and the like on the surface of agricultural machines or parts with rapid wear, so that the surfacing layer has excellent abrasive wear resistance and certain resistance to low stress impact.

[0005] To achieve the above-mentioned purpose, the application realizes the following technical scheme:

[0006] A plasma surfacing flux-cored wire resistant to abrasive wear comprises an outer skin and a core.

[0007] The core comprises the following components in percentage by weight:

[0008] C: 1.6%-3.8%, Si: 0.4%-1.0%, Mn: 0.4%-1.2%, B: 2.10%-4.1%, Cr: 15.0%-24.0%, Nb: 4.1%-7.2%, W: 4.3%-7.7%, La: 0.1%-0.5%, and the rest is Fe.

[0009] The outer skin is a cold-rolled carbon steel strip.

[0010] In the drug core, C comes from one or more of graphite, micro-carbon chromium iron, high-carbon chromium iron, chromium carbide, and cold-rolled carbon steel strip; Si comes from ferrosilicon FeSi75; Mn comes from electrolytic manganese; Cr comes from one or more of high-carbon chromium iron FeCr68C8, micro-carbon chromium iron, and chromium carbide; Nb comes from niobium iron powder; W comes from tungsten carbide; B comes from boron iron; La comes from nano La2O3 powder;

[0011] The C content in the graphite is greater than 99.0wt%; the Si content in the ferrosilicon FeSi75 is 72.0wt%-78.0wt%; the Mn content in the electrolytic manganese is greater than 99.9wt%;

[0012] The Cr content in the high-carbon chromium iron FeCr68C8 is 65.0wt%-69.0wt%, and the C content is 8.0wt%-9.0wt%; the Cr content in the micro-carbon chromium iron is 65.0wt%-69.0wt%, and the C content is 0.01wt%-0.05wt%; the Cr content in the chromium carbide is 88.0wt%-92.0wt%, and the C content is 9.0wt%-11.0wt%;

[0013] The Nb content in the niobium iron powder is greater than 65.0wt%; the W content in the tungsten carbide is greater than 95.0wt%; the B content in the boron iron is greater than 19.3wt%; and the La2O3 content in the nano La2O3 powder is greater than 99.9wt%.

[0014] The particle size of the micro-carbon chromium iron, high-carbon chromium iron, and chromium carbide powder is less than 380um; the particle size of the electrolytic manganese, boron iron, niobium iron, ferrosilicon FeSi75, and micro-carbon chromium iron powder is less than 250um.

[0015] The diameter of the flux-cored wire is 1.2-2.8mm.

[0016] A preparation method of a plasma surfacing flux-cored wire resistant to abrasive wear, comprising the following steps:

[0017] 1) Mix the raw material powders uniformly in a powder mixer, and then place them in a vacuum heating furnace for heating and drying to obtain mixed flux core powder;

[0018] 2) Roll the cold-rolled carbon steel strip into a U-shaped groove, and then add 26%-50% of the mixed flux core powder to the U-shaped groove based on the total weight of the flux-cored wire; close the U-shaped groove to wrap the flux core therein, and then perform draw-drawing and diameter reduction to finally obtain a flux-cored wire with a diameter of 1.2-2.8mm.

[0019] Compared with the prior art, the flux-cored wire has the following beneficial effects:

[0020] 1. The method of the present application produces a plurality of wear particle reinforced plasma surfacing flux-cored wires, under the action of high temperature of plasma surfacing, a plurality of carbides are formed by Cr, W, B, Nb and other alloying elements and carbon elements in the core, generating a network distribution of M7C3 type carbides and dispersed fine MC carbides, fully playing the role of dispersion strengthening and fine grain strengthening; boron elements and alloying elements can form M2B, Fe3(C, B) and other granular or lath-shaped boron-containing strengthening phases, playing the role of precipitation strengthening. Carbides, borides and carborides synergistically play a role to improve the wear resistance of the surfacing layer. Rare earth oxide La2O3 promotes heterogeneous nucleation, refines the primary M7C3 type carbides, so that the micro-peeling and reduced wear resistance are not easy to occur when the organizational structure is subjected to external abrasive wear and rolling.

[0021] 2. The sheath of the flux-cored wire is a cold-rolled carbon steel strip coated with powder. In order to achieve the composition of the final target metal coating, different compositions of the core and the sheath are used, so that the finally prepared coating can meet the design requirements, and the composition adjustment is convenient. The powder used in the present application is a mechanically ground powder, which is low in price and high in economy.

[0022] 3. The surfacing layer metal obtained by using the flux-cored wire for plasma surfacing has high comprehensive mechanical properties, and the hardness can reach above HRC65 after surfacing 4mm. The weight loss of the wear-resistant layer is not more than 0.02g after ASTM-G65 dry sand rubber wheel abrasive wear test, which is used for protection of the easily-worn parts of agricultural machinery, greatly improving the service life of the agricultural machinery. And during the soil entering operation, the single-sided surfacing protection is carried out on the agricultural machinery, the unprotected surface wears fast, and self-sharpening phenomenon occurs, further improving the performance of the agricultural machinery. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the microstructure diagram of the flux-cored wire after plasma surfacing of example 1.

[0024] Figure 2 is the microstructure diagram of the flux-cored wire after plasma surfacing of example 2.

[0025] Figure 3 is the microstructure diagram of the flux-cored wire after plasma surfacing of example 3. DETAILED DESCRIPTION

[0026] The present application will be described in detail below in conjunction with the drawings of the specification, but it should be pointed out that the implementation of the present application is not limited to the following embodiments.

[0027] The anti-abrasive grit wear plasma surfacing flux-cored wire comprises an outer skin and a core; the core comprises, in percentage by mass, C: 3.6%-5.4%, Si: 0.9%-1.2%, Mn: 1.0%-1.8%, B: 2.10%-4.1%, Cr: 40.0%-52.0%, Nb: 4.1%-7.2%, W: 4.3%-7.7%, La: 0.1%-0.5%, and the rest is Fe. The outer skin is an SPCC steel strip. The diameter of the flux-cored wire is 1.2-2.8 mm.

[0028] In the core, C is from one or more of graphite, micro-carbon chromium iron, high-carbon chromium iron and chromium carbide; Si is from silicon iron FeSi75; Mn is from electrolytic manganese; Cr is from one or more of high-carbon chromium iron FeCr68C8, micro-carbon chromium iron and chromium carbide; Nb is from niobium iron powder; W is from tungsten carbide; B is from boron iron; and La is from nano La2O3 powder.

[0029] The content of C in the graphite is greater than 99.0%; the content of Si in the silicon iron FeSi75 is 72.0%-78.0%; the content of Mn in the electrolytic manganese is greater than 99.9%. The content of Cr in the high-carbon chromium iron FeCr68C8 is 65.0%-69.0%, and the content of C is 8.0%-9.0%; the content of Cr in the micro-carbon chromium iron is 65.0%-69.0%, and the content of C is 0.01-0.05%; the content of Cr in the chromium carbide is 88.0%-92.0%, and the content of C is 9.0-11.0%. The content of Nb in the niobium iron powder is greater than 65.0%; the content of W in the tungsten carbide is greater than 95.0wt%; the content of B in the boron iron is greater than 19.3%; and the content of La2O3 in the nano La2O3 powder is greater than 99.9%.

[0030] The micro-carbon chromium iron, the high-carbon chromium iron, the chromium carbide and the reduced iron powder are passed through a 40-mesh sieve, and the powder particle size is ≤380um. The metallic chromium, the FeSi75, the silicon carbide, the electrolytic manganese, the niobium iron and the boron carbide are passed through a 60-mesh sieve, and the powder particle size is ≤250um. The particle size of the tungsten carbide and the graphite is ≤75um. The particle size of the lanthanum oxide is ≤500nm.

[0031] A preparation method of the anti-abrasive grit wear plasma surfacing flux-cored wire comprises the following steps:

[0032] 1) The raw material powders are uniformly mixed in a powder mixer (the powder mixing time is 30-120min), and then are placed in a vacuum heating furnace for heating and drying (the heating temperature is 200-400℃, and the time is 60-180min) to obtain a mixed core powder;

[0033] 2) the cold-rolled carbon steel strip is rolled into a U-shaped groove, and 26% to 50% of the mixed core powder in the total weight of the flux-cored wire is added into the U-shaped groove; the U-shaped groove is closed to wrap the core therein, and through progressive drawing and diameter reduction, the flux-cored wire with a diameter of 1.2 to 2.8 mm is finally obtained.

[0034] In the plasma surfacing process using the flux-cored wire, argon protection is adopted, the surfacing current is 155 to 165 A, the welding gun walking speed is 100 to 150 mm / min, and the ion gas flow is 1.5 to 2 L / min.

[0035] The flux-cored wire can be used for plasma surfacing and laser cladding, and has wide application and strong applicability. The flux-cored wire is resistant to abrasive wear and can resist low stress impact.

[0036] Example 1

[0037] See Figure 1 The preparation method of the flux-cored wire for plasma surfacing resistant to abrasive wear comprises the following steps:

[0038] Step 1: weigh the powder, 3.6 g of micro-carbon chromium iron, 76.4 g of high-carbon chromium iron, 50 g of chromium carbide, 90 g of metallic chromium, 0.4 g of FeSi75, 4.6 g of silicon carbide, 5 g of electrolytic manganese, 76 g of niobium iron, 30 g of boron carbide, 60 g of tungsten carbide, 1 g of graphite, and 3 g of lanthanum oxide, and a total of 400 g of the above components.

[0039] Step 2: mix the powder, and mix the powder in the powder mixer for 30 min.

[0040] Step 3: dry the powder, place the weighed powder in the heating furnace and heat to 300℃ for 120 min to remove the water in the powder.

[0041] Step 4: fill the powder, select a cold-rolled carbon steel strip (such as SPCC steel strip) with a thickness of 0.3 mm and a width of 10 mm as the outer skin, remove the grease on the surface of the outer skin with alcohol, and bend the outer skin into a U shape, fill the powder obtained in step 3 into the outer skin, the powder filling amount is 40%, and then close the outer skin.

[0042] Step 5: draw the wire, and the drawing process is adopted to produce the wire product, and the abrasive-resistant flux-cored wire produced has a diameter of 2.4 mm.

[0043] Step 6: use the prepared ø2.4 mm flux-cored wire to perform plasma surfacing on a Q235 steel plate with a thickness of >4 mm, and air cool to room temperature.

[0044] The hardness of the cladding layer is 65.3 HRC. A friction and wear test is performed by using an ASTM G65 dry sand rubber wheel tester. The contact form of the friction pair is linear contact. The rubber wheel has a diameter of 178 mm and a width of 10 mm, and a hardness of 60 Shore. The load is 130 N, the rotation speed of the rubber wheel is 200 r / min (linear speed is 1.68 m / s), and the abrasive flow is 340-360 g / min. The test time is 3000 revolutions of the rubber wheel. The mass loss of the sample before and after wear is measured by using an analytical balance with a precision of 0.1 mg. The wear loss of the cladding layer is 0.0169 g.

[0045] Example 2

[0046] See Figure 2 The preparation method of the plasma cladding flux-cored wire for resisting abrasive wear includes the following steps:

[0047] Step 1: weigh the powder, 67.1 g of micro-carbon chromium iron, 108.5 g of high-carbon chromium iron, 54.6 g of chromium carbide, 63 g of metallic chromium, 1.6 g of FeSi75, 1.2 g of silicon carbide, 4.0 g of electrolytic manganese, 74 g of niobium iron, 53 g of boron carbide, 68 g of tungsten carbide, 3.0 g of graphite, and 2.0 g of lanthanum oxide, a total of 500 g of the above components.

[0048] Step 2: mix the powder, place the powder in a powder mixer and mix for 30 min.

[0049] Step 3: dry the powder, place the weighed powder in a heating furnace and heat to 300°C for 120 min to remove the water in the powder.

[0050] Step 4: fill the powder, select a cold-rolled carbon steel strip with a thickness of 0.3 mm and a width of 10 mm as the outer skin, remove the grease on the surface of the outer skin with alcohol, bend the outer skin into a U shape, fill the powder obtained in step 3 into the outer skin at a filling amount of 50%, and then close the mouth of the outer skin.

[0051] Step 5: draw the wire, use a drawing process to make the finished product of the wear-resistant flux-cored wire, and the diameter of the wear-resistant flux-cored wire is 2.8 mm.

[0052] Step 6: use the prepared ø2.8 mm flux-cored wire to perform cladding on a Q235 steel plate by using a plasma cladding machine, the thickness is >4 mm, and air cooling to room temperature.

[0053] Example 3

[0054] See Figure 3 The preparation method of the plasma cladding flux-cored wire for resisting abrasive wear includes the following steps:

[0055] Step 1: Take the powder, micro-carbon chromium iron 42g, high-carbon chromium iron 77g, chromium carbide 25g, metallic chromium 40g, FeSi75 2.0g, silicon carbide 1.0g, electrolytic manganese 2.3g, niobium iron 66g, boron carbide 44g, tungsten carbide 48g, graphite 1.0g, lanthanum oxide 1.7g, the above components are 350g.

[0056] Step 2: Mix the powder, put the powder in the powder mixer and mix for 30 minutes.

[0057] Step 3: Dry the powder, put the weighed powder into the heating furnace and heat to 300℃ for 120 minutes to remove the moisture in the powder.

[0058] Step 4: Fill the powder, choose a cold-rolled carbon steel strip with a thickness of 0.3mm and a width of 10mm as the outer skin, use alcohol to remove the grease on the surface of the outer skin, and bend the outer skin into a U shape, fill the powder obtained in step 3 into the outer skin, the powder filling amount is 35%, and then close the outer skin.

[0059] Step 5: Draw the welding wire, use the drawing process to make the welding wire product, the wear-resistant flux-cored welding wire made has a diameter of 1.6mm.

[0060] Step 6: Stack the prepared ø1.6mm flux-cored welding wire on the Q235 steel plate with a plasma stacker, the thickness is >4mm, and air cool to room temperature.

[0061] Example 4

[0062] The preparation method of the plasma surfacing flux-cored welding wire for resisting abrasive wear includes the following steps:

[0063] Step 1: Take the powder, micro-carbon chromium iron 68g, high-carbon chromium iron 55.8g, chromium carbide 145g, metallic chromium 21g, FeSi75 2.0g, silicon carbide 1.5g, electrolytic manganese 4.4g, niobium iron 72g, boron carbide 28g, tungsten carbide 76g, graphite 3.5g, lanthanum oxide 2.8g, the above components are 480g.

[0064] Step 2: Mix the powder, put the powder in the powder mixer and mix for 30 minutes.

[0065] Step 3: Dry the powder, put the weighed powder into the heating furnace and heat to 300℃ for 120 minutes to remove the moisture in the powder.

[0066] Step 4: Fill the powder, choose a cold-rolled carbon steel strip with a thickness of 0.3mm and a width of 10mm as the outer skin, use alcohol to remove the grease on the surface of the outer skin, and bend the outer skin into a U shape, fill the powder obtained in step 3 into the outer skin, the powder filling amount is 48%, and then close the outer skin.

[0067] Step 5: Drawing the welding wire, using a drawing process to make the welding wire finished product, the wear-resistant flux-cored wire made has a diameter of 2.8 mm.

[0068] Step 6: The prepared ø2.8 mm flux-cored wire is surfacing on a Q235 steel plate using a plasma surfacing machine, with a thickness of >4 mm, and air cooling to room temperature.

[0069] Example 5

[0070] The preparation method of the plasma surfacing flux-cored wire resistant to abrasive wear includes the following steps:

[0071] Step 1: Weigh the powder, 126.5 g of micro-carbon chromium iron, 42 g of high-carbon chromium iron, 34 g of chromium carbide, 18 g of metallic chromium, 1.8 g of FeSi75, 1.5 g of silicon carbide, 5.0 g of electrolytic manganese, 92 g of niobium iron, 53.5 g of boron carbide, 81.5 g of tungsten carbide, 2.0 g of graphite, and 2.2 g of lanthanum oxide, a total of 460 g of the above components.

[0072] Step 2: Mix the powder, place the powder in the powder mixer and mix for 30 minutes.

[0073] Step 3: Dry the powder, place the weighed powder in a heating furnace and heat to 300°C for 120 minutes to remove the moisture in the powder.

[0074] Step 4: Fill the powder, select a cold-rolled carbon steel strip with a thickness of 0.3 mm and a width of 10 mm as the outer skin, use alcohol to remove the grease on the surface of the outer skin, and bend the outer skin into a U shape, fill the powder obtained in step 3 into the outer skin, the powder filling amount is 46%, and then close the outer skin.

[0075] Step 5: Draw the welding wire, use a drawing process to make the welding wire finished product, the wear-resistant flux-cored wire made has a diameter of 2.8 mm.

[0076] Step 6: The prepared ø2.8 mm flux-cored wire is surfacing on a Q235 steel plate using a plasma surfacing machine, with a thickness of >4 mm, and air cooling to room temperature.

[0077] Example 6

[0078] The preparation method of the plasma surfacing flux-cored wire resistant to abrasive wear includes the following steps:

[0079] Step 1: Weigh the powder, 220 g of micro-carbon chromium iron, 59 g of high-carbon chromium iron, 35.4 g of chromium carbide, 15 g of metallic chromium, 2.1 g of FeSi75, 1.5 g of silicon carbide, 5.0 g of electrolytic manganese, 68 g of niobium iron, 32 g of boron carbide, 48 g of tungsten carbide, 2.0 g of graphite, and 2.0 g of lanthanum oxide, a total of 490 g of the above components.

[0080] Step 2: mixing the medicine powder, the medicine powder is placed in a powder mixer for 30 minutes.

[0081] Step 3: drying the medicine powder, the weighed medicine powder is placed in a heating furnace and heated to 300 DEG C for 120 minutes to remove the water in the medicine powder.

[0082] Step 4: filling the medicine powder, a cold-rolled carbon steel strip with a thickness of 0.3 mm and a width of 10 mm is selected as the outer skin, alcohol is used to remove the grease on the surface of the outer skin, the outer skin is bent into a U shape, the medicine powder obtained in step 3 is filled into the outer skin, the filling amount of the medicine powder is 49%, and the outer skin is closed.

[0083] Step 5: drawing the welding wire, a welding wire product is prepared by using a drawing process, and the prepared wear-resistant flux-cored welding wire has a diameter of 2.8 mm.

[0084] Step 6: the prepared ø2.8 mm flux-cored welding wire is stacked on a Q235 steel plate by using a plasma surfacing machine, the thickness is greater than 4 mm, and the air cooling is performed to room temperature.

[0085] The performance of the welding layer is shown in Table 1.

[0086] Table 1

[0087]

[0088] The prepared flux-cored welding wire has certain resistance to low stress impact, the surface of the agricultural implement is strengthened by using the plasma surfacing technology, the surfacing or cladding is performed on the fast-wearing part for reinforcement, and the prepared flux-cored welding wire has the advantages of low cost, good wear resistance, simple process and the like.

Claims

1. A plasma surfacing flux cored welding wire resistant to abrasive wear, characterized in that, The drug core comprises an outer skin and a drug core; The drug core comprises the following components in percentage by weight C: 1.6%~3.8%, Si: 0.4%~1.0%, Mn: 0.4%~1.2%, B: 2.10%~4.1%, Cr: 15.0%~24.0%, Nb: 4.1%~7.2%, W: 4.3%~7.7%, La: 0.1%~0.5%, and the rest is Fe; The outer skin is a cold-rolled carbon steel strip; In the drug core, C is from one or more of graphite, micro-carbon ferrochrome, high-carbon ferrochrome, chromium carbide, and cold-rolled carbon steel strip; Si is from ferrosilicon FeSi75; Mn is from electrolytic manganese; Cr is from one or more of high-carbon ferrochrome FeCr68C8, micro-carbon ferrochrome, and chromium carbide; Nb is from ferro-niobium powder; W is from tungsten carbide; B is from ferro-boron; and La is from nano La2O3 powder; The content of C in the graphite is greater than 99.0wt%; the content of Si in the ferrosilicon FeSi75 is 72.0wt%~78.0wt%; and the content of Mn in the electrolytic manganese is greater than 99.9wt%; In the high-carbon ferrochrome FeCr68C8, the content of Cr is 65.0wt%~69.0wt% and the content of C is 8.0wt%~9.0wt%; in the micro-carbon ferrochrome, the content of Cr is 65.0wt%~69.0wt% and the content of C is 0.01wt%~0.05wt%; and in the chromium carbide, the content of Cr is 88.0wt%~92.0wt% and the content of C is 9.0wt%~11.0wt%; In the ferro-niobium powder, the content of Nb is greater than 65.0wt%; in the tungsten carbide, the content of W is greater than 95.0wt%; in the ferro-boron, the content of B is greater than 19.3wt%; and in the nano La2O3 powder, the content of La2O3 is greater than 99.9wt%.

2. A plasma arc surfacing flux cored welding wire resistant to abrasive wear according to claim 1, characterized in that, The particle size of the micro-carbon ferrochrome, high-carbon ferrochrome, and chromium carbide powder is less than 380um; the particle size of the electrolytic manganese, ferro-boron, ferro-niobium, ferrosilicon FeSi75, and micro-carbon ferrochrome powder is less than 250um.

3. A plasma arc surfacing flux cored welding wire resistant to abrasive wear according to claim 1, wherein The diameter of the drug core welding wire is 1.2~2.8mm.

4. A method of making a plasma surfacing flux cored welding wire resistant to abrasive wear according to any one of claims 1-3, characterized in that, The method comprises the following steps: 1) uniformly mixing the powders of raw materials in a powder mixer, and then placing them in a vacuum heating furnace for heating and drying to obtain mixed drug core powder; 2) rolling the cold-rolled carbon steel strip into a U-shaped groove, adding 26%~50% of the total weight of the drug core welding wire into the U-shaped groove, and then closing the U-shaped groove to wrap the drug core therein, and finally obtaining the drug core welding wire with a diameter of 1.2~2.8mm through progressive drawing and reducing the diameter.

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