High-hardness and high-toughness laser cladding flux-cored wire and application thereof

Abstract

The application relates to the technical field of welding materials, and discloses a high-hardness and high-toughness laser cladding flux-cored wire and application thereof. The high-hardness and high-toughness laser cladding flux-cored wire comprises a core and an outer skin coated on the surface of the core, and the core is composed of the following components: C, Cr, Nb, W, V, Mo, Ni, N, Si, Mn, Ti, rare earth elements, a deoxidizing agent, and the balance of iron and inevitable impurities; wherein the mass content of V, W and Mo is in a relationship of (W+1.5V) / Mo=1.5-4.5. Through the technical scheme, the problem of poor high-temperature hardness of a laser cladding layer in the related art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding materials, in particular to a high-hardness and high-toughness laser cladding flux-cored wire and application thereof. BACKGROUND

[0002] Laminar flow roller is the core component of the steel hot-rolled laminar flow cooling system, which can support and guide high-temperature steel plates, and cooperate with high-pressure water spraying to realize rapid and uniform cooling of the steel plates. The laminar flow roller needs to withstand high-temperature baking, high-humidity water vapor erosion, and severe alternating thermal stress for a long time, and mechanical collision in the process of steel plate conveying. The working environment is very harsh. In order to effectively resist high-temperature oxidation, thermal corrosion and erosion wear, and avoid premature failure of the roller surface, the roller surface must have strong high-temperature hardness to adapt to complex working conditions.

[0003] Laser cladding technology, as an advanced roller surface modification and repair method, is an ideal choice to improve the performance of the laminar flow roller surface. However, the existing mainstream ordinary iron-based alloy laser cladding flux-cored wire has poor high-temperature hardness, which is difficult to continuously resist erosion wear and high-temperature corrosion, and cannot meet the core needs of long-term stable use of the laminar flow roller, limiting the application effect of laser cladding technology in the strengthening and repair of the laminar flow roller. SUMMARY

[0004] The present application provides a high-hardness and high-toughness laser cladding flux-cored wire and application thereof, which solves the problem of poor high-temperature hardness of the laser cladding layer in the related art.

[0005] The technical scheme of the present application is as follows:

[0006] A high-hardness and high-toughness laser cladding flux-cored wire, comprising a core and an outer skin covering the surface of the core, wherein the core is composed of the following components in mass percentage: C 0.15%~0.5%, Cr 16%~19%, Nb 0.5%~1.2%, W 1.5%~2.5%, V 0.8%~1.4%, Mo 0.8%~2.1%, Ni 2.5%~3.5%, N 0.1%~0.2%, Si 0.4%~0.8%, Mn 0.8%~1.2%, Ti 0.3%~0.6%, rare earth elements 0.1%~0.2%, deoxidizing agent 1%~2%, and the balance is iron and unavoidable impurities.

[0007] The mass content of V, W and Mo satisfies the relationship (W+1.5V) / Mo=1.5~4.5.

[0008] As a further technical scheme, the mass content of V and W satisfies the relationship W / V=1.5~2.5, preferably 2.

[0009] As a further technical solution, the total mass content of the four elements Nb, V, W and Mo in the core is 4.5% to 6.6%, preferably 5%.

[0010] The high-hardness and high-toughness laser cladding core wire can ensure that the four elements form sufficient and not excessive carbides in the cladding layer, wherein Nb can generate stable NbC, produce grain boundary pinning effect, effectively prevent grain growth and carbide coarsening at high temperature; W and Mo cooperatively form stable carbides, and jointly improve high-temperature strength; V generates high-hardness and dispersedly distributed VC, which can refine grains and improve toughness, and the four elements cooperatively form stable and dispersedly distributed carbide strengthening phase network with C and Cr, avoiding insufficient carbides and high-temperature hardness due to too low element content.

[0011] As a further technical solution, the rare earth elements include Ce and La.

[0012] Ce and La and other rare earth elements have excellent deoxidizing and desulfurizing capacity, can purify grain boundaries, and make inclusions spheroidized, thereby improving high-temperature oxidation resistance and fatigue resistance of the cladding layer.

[0013] As a further technical solution, the mass content relationship of Ce and La is: Ce / La=3 to 5, preferably 4.

[0014] As a further technical solution, the material of the sheath is low-carbon steel, and the low-carbon steel consists of the following components in mass percentage: C 0.04% to 0.07%, Mn 0.35% to 0.65%, Si 0.02% to 0.05%, Cr 0.28% to 0.45%, S≤0.012%, P≤0.015%, and the balance is iron and unavoidable impurities.

[0015] As a further technical solution, the deoxidizer includes sodium fluozirconate and cesium fluoroaluminate.

[0016] The present application can improve the impact toughness of the cladding layer through the synergistic effect of sodium fluozirconate and cesium fluoroaluminate as the core deoxidizer of the core wire: zirconium in sodium fluozirconate can form fine oxynitride, making the cladding metal organization uniform and the grain refined; cesium fluoroaluminate can capture residual oxygen and nitrogen, inhibit the formation of oxidized inclusions, and improve the wettability and density of the cladding layer metal; the two synergistically enhance the impact toughness of the cladding layer through multiple effects such as grain refinement, deoxidization and nitrogen reduction, improved wettability and inhibited harmful oxide inclusions.

[0017] As a further technical solution, the mass ratio of sodium fluozirconate and cesium fluoroaluminate is 2 to 5:4.

[0018] As a further technical solution, the high-hardness and high-toughness laser cladding flux-cored wire has a diameter of 2-3 mm.

[0019] The application further provides application of the high-hardness and high-toughness laser cladding flux-cored wire in repair or manufacturing of laminar flow rollers.

[0020] The working principle and advantages of the application are as follows:

[0021] The high-hardness and high-toughness laser cladding flux-cored wire limits the mass content relationship of V, W and Mo in the core to satisfy the value of (W+1.5V) / Mo being 1.5-4.5, so as to improve the high-temperature hardness of the flux-cored wire. When the value of (W+1.5V) / Mo is 1.5-4.5, the synergistic effect of carbides of W, V and Mo can be optimized, the high-temperature stability contributed by W and Mo and the dispersion strengthening and grain refinement effect contributed by V are balanced, the cladding layer can have sufficient and stable carbide support hardness in a high-temperature environment, and the high-temperature performance short board caused by excessive or insufficient single element can be avoided through reasonable element matching, and finally the high-temperature hardness of the flux-cored wire cladding layer is improved. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor also fall within the protection scope of the application.

[0023] Embodiment 1

[0024] A high-hardness and high-toughness laser cladding flux-cored wire has a diameter of 2.5 mm and comprises a core and an outer skin covering the surface of the core.

[0025] The core is composed of the following components in terms of mass percentage: C 0.15%, Cr 16%, Nb 1%, W 1.5%, V 1%, Mo 1.5%, Ni 2.5%, N 0.1%, Si 0.4%, Mn 0.8%, Ti 0.3%, rare earth elements 0.1%, deoxidizer 1%, and the balance being iron and inevitable impurities. The total mass content of the four elements of Nb, V, W and Mo is 5%, the mass content relationship of V, W and Mo satisfies the value of (W+1.5V) / Mo being 2, the mass content relationship of V and W satisfies the value of W / V being 1.5, the rare earth elements are composed of Ce and La in a mass ratio of 4:1, and the deoxidizer is cesium fluoroaluminate.

[0026] The material of the sheath is low carbon steel, and the low carbon steel is composed of the following components in percentage by mass: C 0.04%, Mn 0.35%, Si 0.02%, Cr 0.28%, S 0.008%, P 0.01%, and the balance of iron and inevitable impurities.

[0027] Example 2

[0028] A high-hardness and high-toughness laser cladding flux-cored wire has a diameter of 2.5 mm and comprises a core and a sheath coated on the surface of the core;

[0029] The core is composed of the following components in percentage by mass: C 0.5%, Cr 19%, Nb 1%, W 1.5%, V 1%, Mo 1.5%, Ni 3.5%, N 0.2%, Si 0.8%, Mn 1.2%, Ti 0.6%, rare earth elements 0.2%, and deoxidizer 2%, and the balance of iron and inevitable impurities; wherein the total mass content of the four elements of Nb, V, W and Mo is 5%; the mass content relationship of V, W and Mo is that the value of (W+1.5V) / Mo is 2; the mass content relationship of V and W is that the value of W / V is 1.5; the rare earth elements are composed of Ce and La in a mass ratio of 4:1; and the deoxidizer is cesium fluoroaluminate.

[0030] The material of the sheath is low carbon steel, and the low carbon steel is composed of the following components in percentage by mass: C 0.05%, Mn 0.5%, Si 0.04%, Cr 0.35%, S 0.01%, P 0.013%, and the balance of iron and inevitable impurities.

[0031] Example 3

[0032] A high-hardness and high-toughness laser cladding flux-cored wire has a diameter of 2.5 mm and comprises a core and a sheath coated on the surface of the core;

[0033] The core is composed of the following components in percentage by mass: C 0.5%, Cr 19%, Nb 1%, W 1.5%, V 1%, Mo 1.5%, Ni 3.5%, N 0.2%, Si 0.8%, Mn 1.2%, Ti 0.6%, rare earth elements 0.2%, and deoxidizer 2%, and the balance of iron and inevitable impurities; wherein the total mass content of the four elements of Nb, V, W and Mo is 5%; the mass content relationship of V, W and Mo is that the value of (W+1.5V) / Mo is 2; the mass content relationship of V and W is that the value of W / V is 1.5; the rare earth elements are composed of Ce and La in a mass ratio of 4:1; and the deoxidizer is cesium fluoroaluminate.

[0034] The material of the outer skin is low carbon steel, which consists of the following components in mass percentage: C 0.07%, Mn 0.65%, Si 0.05%, Cr 0.45%, S 0.012%, P 0.015%, and the balance of iron and inevitable impurities.

[0035] Example 4

[0036] Compared with Example 2, the difference of Example 4 is that the core in this example consists of the following components in mass percentage: C 0.35%, Cr 17.5%, Nb 1.2%, W 1.6%, V 0.8%, Mo 1.4%, Ni 3%, N 0.15%, Si 0.6%, Mn 1%, Ti 0.5%, rare earth elements 0.15%, deoxidizing agent 1.5%, and the balance of iron and inevitable impurities; wherein the total mass content of the four elements of Nb, V, W and Mo is 5%; the mass content relationship of V, W and Mo is that the value of (W+1.5V) / Mo is 2; the mass content relationship of V and W is that the value of W / V is 2.

[0037] Example 5

[0038] Compared with Example 2, the difference of Example 5 is that the core in this example consists of the following components in mass percentage: C 0.35%, Cr 17.5%, Nb 0.6%, W 2%, V 0.8%, Mo 1.6%, Ni 3%, N 0.15%, Si 0.6%, Mn 1%, Ti 0.5%, rare earth elements 0.15%, deoxidizing agent 1.5%, and the balance of iron and inevitable impurities; wherein the total mass content of the four elements of Nb, V, W and Mo is 5%; the mass content relationship of V, W and Mo is that the value of (W+1.5V) / Mo is 2; the mass content relationship of V and W is that the value of W / V is 2.5.

[0039] Example 6

[0040] Compared with Example 2, the difference of Example 6 is that the core in this example consists of the following components in mass percentage: C 0.35%, Cr 17.5%, Nb 1%, W 2%, V 1%, Mo 1%, Ni 3%, N 0.15%, Si 0.6%, Mn 1%, Ti 0.5%, rare earth elements 0.15%, deoxidizing agent 1.5%, and the balance of iron and inevitable impurities; wherein the total mass content of the four elements of Nb, V, W and Mo is 5%; the mass content relationship of V, W and Mo is that the value of (W+1.5V) / Mo is 3.5; the mass content relationship of V and W is that the value of W / V is 2.

[0041] Example 7

[0042] The difference between example 7 and example 2 is that, in the present example, the core wire consists of the following components by mass percentage: C 0.35%, Cr 17.5%, Nb 0.92%, W 2.16%, V 1.08%, Mo 0.84%, Ni 3%, N 0.15%, Si 0.6%, Mn 1%, Ti 0.5%, rare earth elements 0.15%, deoxidizing agent 1.5%, and the balance being iron and unavoidable impurities; wherein the total mass content of the four elements Nb, V, W and Mo is 5%; the mass content relationship of V, W and Mo is that the value of (W+1.5V) / Mo is 4.5; and the mass content relationship of V and W is that the value of W / V is 2.

[0043] Example 8

[0044] A high-hardness and high-toughness laser cladding flux-cored wire, having a diameter of 2.5 mm, comprises a core and an outer sheath covering the surface of the core;

[0045] The core consists of the following components by mass percentage: C 0.35%, Cr 16.5%, Nb 0.85%, W 1.6%, V 0.85%, Mo 1.6%, Ni 2.7%, N 0.12%, Si 0.5%, Mn 0.9%, Ti 0.35%, rare earth elements 0.12%, deoxidizing agent 1%, and the balance being iron and unavoidable impurities; the rare earth elements consist of Ce and La in a mass ratio of 4:1; and the deoxidizing agent is cesium fluoroaluminate.

[0046] The material of the outer sheath is low-carbon steel, which consists of the following components by mass percentage: C 0.05%, Mn 0.5%, Si 0.04%, Cr 0.35%, S 0.01%, P 0.013%, and the balance being iron and unavoidable impurities.

[0047] Example 9

[0048] The difference between example 9 and example 8 is that, in the present example, the core wire consists of the following components by mass percentage: C 0.35%, Cr 17.5%, Nb 1%, W 2%, V 1%, Mo 1.75%, Ni 3%, N 0.15%, Si 0.6%, Mn 1%, Ti 0.45%, rare earth elements 0.15%, deoxidizing agent 1%, and the balance being iron and unavoidable impurities.

[0049] Example 10

[0050] The difference between example 10 and example 8 is that, in example 10, the core wire is composed of the following components in percentage by mass: C 0.5%, Cr 18.5%, Nb 1.15%, W 2.4%, V 1.1%, Mo 1.9%, Ni 3.3%, N 0.18%, Si 0.7%, Mn 1.1%, Ti 0.55%, rare earth elements 0.18%, deoxidizer 1%, and the balance of iron and inevitable impurities.

[0051] Example 11

[0052] The difference between example 11 and example 1 is that, in example 11, the core wire is composed of the following components in percentage by mass: C 0.15%, Cr 16%, Nb 0.5%, W 1.5%, V 1%, Mo 1.5%, Ni 2.5%, N 0.1%, Si 0.4%, Mn 0.8%, Ti 0.3%, rare earth elements 0.1%, deoxidizer 1%, and the balance of iron and inevitable impurities; wherein the total mass content of the four elements of Nb, V, W and Mo is 4.5%; the mass content relationship of V, W and Mo is that the value of (W+1.5V) / Mo is 2; the mass content relationship of V and W is that the value of W / V is 1.5; the rare earth elements are composed of Ce and La in a mass ratio of 4:1; and the deoxidizer is cesium fluoroaluminate.

[0053] Example 12

[0054] The difference between example 12 and example 1 is that, in example 12, the core wire is composed of the following components in percentage by mass: C 0.15%, Cr 16%, Nb 1.2%, W 2.025%, V 1.35%, Mo 2.025%, Ni 2.5%, N 0.1%, Si 0.4%, Mn 0.8%, Ti 0.3%, rare earth elements 0.1%, deoxidizer 1%, and the balance of iron and inevitable impurities; wherein the total mass content of the four elements of Nb, V, W and Mo is 6.6%; the mass content relationship of V, W and Mo is that the value of (W+1.5V) / Mo is 2; the mass content relationship of V and W is that the value of W / V is 1.5; the rare earth elements are composed of Ce and La in a mass ratio of 4:1; and the deoxidizer is cesium fluoroaluminate.

[0055] Example 13

[0056] The difference between example 13 and example 6 is that, in example 13, the deoxidizer is composed of sodium fluozirconate and cesium fluoroaluminate in a mass ratio of 1:2.

[0057] Example 14

[0058] The difference between Example 14 and Example 6 is that the deoxidizer in this example is composed of sodium fluorozirconate and cesium fluoroaluminate with a mass ratio of 3:4.

[0059] Example 15

[0060] The difference between Example 15 and Example 6 is that the deoxidizer in this example is composed of sodium fluorozirconate and cesium fluoroaluminate with a mass ratio of 5:4.

[0061] Example 16

[0062] The difference between Example 16 and Example 6 is that the deoxidizer in this example is only sodium fluorozirconate.

[0063] Comparative Example 1

[0064] The difference between Comparative Example 1 and Example 1 is that the core in this comparative example does not contain Nb, and the total mass percentage of W, V and Mo is 4.5%, and the mass ratio of W, V and Mo is 3:2:3.

[0065] Comparative Example 2

[0066] The difference between Comparative Example 2 and Example 1 is that the core in this comparative example does not contain W, and the total mass percentage of Nb, V and Mo is 4.5%, and the mass ratio of Nb, V and Mo is 1:2:3.

[0067] Comparative Example 3

[0068] The difference between Comparative Example 3 and Example 1 is that the core in this comparative example does not contain V, and the total mass percentage of Nb, W and Mo is 4.5%, and the mass ratio of Nb, W and Mo is 1:3:3.

[0069] Comparative Example 4

[0070] The difference between Comparative Example 4 and Example 1 is that the core in this comparative example does not contain Mo, and the total mass percentage of Nb, W and V is 4.5%, and the mass ratio of Nb, W and V is 1:3:2.

[0071] Comparative Example 5

[0072] The difference between Comparative Example 5 and Example 1 is that the core in this comparative example does not contain Nb and W, and the total mass percentage of V and Mo is 4.5%, and the mass ratio of V and Mo is 2:3.

[0073] Comparative Example 6

[0074] The difference of Comparative Example 6 compared to Example 1 is that the core of this comparative example does not contain Nb and V, and the total mass percentage of W and Mo is 4.5%, wherein the mass ratio of W to Mo is 1:1.

[0075] Comparative Example 7

[0076] The difference of Comparative Example 7 compared to Example 1 is that the core of this comparative example does not contain Nb and Mo, and the total mass percentage of W and V is 4.5%, wherein the mass ratio of W to V is 3:2.

[0077] Comparative Example 8

[0078] The difference of Comparative Example 8 compared to Example 1 is that the core of this comparative example does not contain W and V, and the total mass percentage of Nb and Mo is 4.5%, wherein the mass ratio of Nb to Mo is 1:3.

[0079] Comparative Example 9

[0080] The difference of Comparative Example 9 compared to Example 1 is that the core of this comparative example does not contain W and Mo, and the total mass percentage of Nb and V is 4.5%, wherein the mass ratio of Nb to V is 1:2.

[0081] Comparative Example 10

[0082] The difference of Comparative Example 10 compared to Example 1 is that the core of this comparative example does not contain V and Mo, and the total mass percentage of Nb and W is 4.5%, wherein the mass ratio of Nb to W is 1:3.

[0083] Comparative Example 11

[0084] The difference of Comparative Example 11 compared to Example 1 is that the core of this comparative example does not contain W, V and Mo, and the mass percentage of Nb is 4.5%.

[0085] Comparative Example 12

[0086] The difference of Comparative Example 12 compared to Example 1 is that the core of this comparative example does not contain Nb, V and Mo, and the mass percentage of W is 4.5%.

[0087] Comparative Example 13

[0088] The difference of Comparative Example 13 compared to Example 1 is that the core of this comparative example does not contain Nb, W and Mo, and the mass percentage of V is 4.5%.

[0089] Comparative Example 14

[0090] The difference between Comparative Example 14 and Example 1 is that the core of the present comparative example does not contain Nb, W, V, and the mass percentage of Mo is 4.5%.

[0091] Comparative Example 15

[0092] The difference between Comparative Example 15 and Example 1 is that the core of the present comparative example does not contain Nb, W, V, and Mo.

[0093] Comparative Example 16

[0094] The difference between Comparative Example 16 and Example 1 is that the core of the present comparative example consists of the following components by mass percentage: C 4.5%, Cr 28%, Mo 3.5%, Ni 1%, Si 1%, Mn 1%, and the balance of Fe and inevitable impurities.

[0095] After the low-carbon steel sheath of Examples 1-16 and Comparative Examples 1-16 is rolled into a U-shaped groove, the mixed and uniform core is added, sealed, reduced in diameter, and drawn into a laser cladding core wire;

[0096] Under the laser cladding process parameters of laser power 3.5kW, scanning speed 8mm / s, and overlap rate 40%, the laser cladding core wires prepared from Examples 1-16 and Comparative Examples 1-16 are used to prepare cladding layers on a 45 steel substrate under a nitrogen atmosphere, and the performance of the cladding layers is tested according to the following test methods;

[0097] 1. High temperature hardness: The high temperature hardness of the cladding layer is tested according to the test method specified in the standard T / CSTM 00650-2021 “Metallic Materials High Temperature Vickers Hardness Test Method”, and the test holding time is 10s;

[0098] 2. Impact toughness: The impact toughness of the cladding layer is tested according to the test method specified in the standard GB / T 229-2020 “Metallic Materials Charpy Pendulum Impact Test Method”, the hammer edge curvature radius of the pendulum hammer is 2mm, and the sample type is a V-shaped notch sample;

[0099] 3. Room temperature hardness: The room temperature hardness of the cladding layer is tested according to the test method specified in the standard GB / T 230.1-2018 “Metallic Materials Rockwell Hardness Test Part 1: Test Method”, and the type of spherical indenter is tungsten carbide alloy;

[0100] 4. Thermal shock resistance: according to the thermal cycle resistance performance related test method specified in the standard GB / T 42259-2022 "Metal and other inorganic coating thermal barrier coating thermal cycle and thermal shock resistance test method", the thermal shock resistance of the cladding layer is tested; the single thermal cycle mode is to heat from 200℃ to 1100℃ for 10min and keep for 30min, then cool from 1100℃ to 200℃ by water cooling for 15min and keep for 5min; the number of thermal cycles until cracking is tested;

[0101] The test results are shown in Tables 1, 2 and 3.

[0102] Table 1 High temperature hardness test results of the cladding layer

[0103]

[0104] From the data in Table 1, it can be seen that the comparison of Examples 1-12 and Comparative Examples 1-16 shows that the addition of Nb, V, W and Mo can significantly improve the high temperature hardness of the cladding layer prepared by the laser cladding flux-cored wire of the present application.

[0105] Table 2 Impact toughness test results of the cladding layer

[0106]

[0107] From the data in Table 2, it can be seen that the comparison of Examples 6, 8-10, 13-16 and Comparative Example 16 shows that the addition of the deoxidizer composed of sodium fluorozirconate and cesium fluoroaluminate can significantly improve the impact toughness of the cladding layer prepared by the laser cladding flux-cored wire of the present application.

[0108] Table 3 Other performance test results of the cladding layer

[0109]

[0110] From the data in Table 3, it can be seen that the laser cladding flux-cored wire of the present application has a higher room temperature hardness and excellent thermal shock resistance.

[0111] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high hardness, high toughness laser clad cored wire, characterized by, The high-hardness and high-toughness laser cladding flux-cored wire comprises a core and a sheath covering the surface of the core, and the core is composed of the following components in percentage by mass: C 0.15%-0.5%, Cr 16%-19%, Nb 0.5%-1.2%, W 1.5%-2.5%, V 0.8%-1.4%, Mo 0.8%-2.1%, Ni 2.5%-3.5%, N 0.1%-0.2%, Si 0.4%-0.8%, Mn 0.8%-1.2%, Ti 0.3%-0.6%, rare earth elements 0.1%-0.2%, deoxidizing agent 1%-2%, and the balance being iron and inevitable impurities. The total mass content of the four elements Nb, V, W and Mo in the core is 4.5%-6.6%. The mass content relationship of V, W and Mo is (W+1.5V) / Mo=1.5-4.

5. The deoxidizing agent comprises sodium fluozirconate and cesium fluoroaluminate.

2. The high hardness, high toughness laser clad flux cored wire of claim 1, wherein, The mass content relationship of V and W is W / V=1.5-2.

5.

3. The high hardness, high toughness laser clad flux cored wire of claim 1, wherein, The rare earth elements comprise Ce and La.

4. The high hardness, high toughness laser clad flux cored wire of claim 3, wherein, The mass content relationship of Ce and La is Ce / La=3-5.

5. The high hardness, high toughness laser clad cored wire of claim 1, wherein, The material of the sheath is low-carbon steel, and the low-carbon steel is composed of the following components in percentage by mass: C 0.04%-0.07%, Mn 0.35%-0.65%, Si 0.02%-0.05%, Cr 0.28%-0.45%, S≤0.012%, P≤0.015%, and the balance being iron and inevitable impurities.

6. The high hardness, high toughness laser clad flux cored wire of claim 1, wherein, The mass ratio of the sodium fluozirconate and the cesium fluoroaluminate is 2-5:

4.

7. The high hardness, high toughness laser clad flux cored wire of claim 1, wherein, The diameter of the high-hardness and high-toughness laser cladding flux-cored wire is 2-3 mm.

8. The use of the high-hardness and high-toughness laser cladding flux-cored wire according to any one of claims 1-7 in the repair or manufacture of laminar flow rolls.

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