Nickel-based powder-cored wire

Abstract

The invention discloses a nickel-based powder core welding wire which comprises an outer skin and a powder core, and the outer skin wraps the powder core. The outer skin is a nickel-chromium alloy belt, and the powder core comprises 1%-8% of metal chromium powder, 8%-20% of metal manganese powder, 2%-20% of metal molybdenum powder, 35%-50% of metal iron powder, 0%-2% of ferrotitanium powder, 0%-3% of ferrovanadium powder and ferrosilicon powder lt. 2% of ferrocolumbium powder, 2%-6% of fluorite, 1%-3% of rutile, 1%-3% of quartz, 3%-8% of marble and 1t of feldspar; 3%, and the balance of metal nickel powder. The nickel-based powder-cored wire is suitable for welding under the high-stress condition, and an obtained welding seam is not prone to cracking and high in plasticity and toughness.

Description

Technical Field

[0001] The invention relates to the technical field of welding, in particular to a nickel-based powder cored welding wire used for welding under high stress conditions. Background Art

[0002] The production time of large and heavy equipment is generally 2 to 6 years and the price is high. If new equipment is used to replace old equipment, the cost faced by end users is very high and they generally do not choose to replace new equipment. Therefore, maintenance and life extension become the only option to extend the service life of old equipment.

[0003] Large and heavy equipment is basically made of steel (iron-based alloy) materials. Surface wear and cracking are important forms of failure. Due to high stress and direct contact with the outside world, it is easy to fail during service. During the repair process, high stress conditions put forward very high requirements on the performance of the weld. If iron-based alloy welding materials are used for welding, in order to reduce the formation of cracks in the weld area, the repair area needs to be heated to 150-300°C before welding, and the temperature must be maintained in this range during the welding process. The working environment of the welder is very harsh. In addition, many times it is high-altitude work, the labor intensity is high, and the risk of accidents is high. Repair with high crack resistance nickel-based alloy can be constructed with almost no preheating, and the weld will not crack, which can meet the repair strength requirements. This is because the crystal structure of nickel-based alloys has only one form of face-centered cubic, and will not undergo phase change during welding to form a hard and brittle phase, avoiding the situation that most iron-based alloys are prone to form brittle and hard phases and cracking during welding. In addition, the solid solution-strengthened nickel-based alloy has many slip systems, strong deformation ability under high stress, and will not crack due to high stress.

[0004] Most existing nickel-based alloy wires are solid wires, which have poor forming and are prone to defects when used in all-position welding with metal arc welding. By adding mineral powder to the powder core wire, an effective slag shell is formed on the surface of the molten pool to protect the forming, which not only improves the forming but also reduces the defects. In addition, the composition of the solid wire is fixed and cannot fully adapt to the repair of metals with different components. Especially when the S content in the base metal is high, the nickel-based alloy weld is prone to defects. The alloy elements provided by this patent are adjusted according to the composition of the metal to be repaired, and the influence of harmful elements such as S is reduced by increasing the content of Mn and Mo elements, making the welding wire more suitable for the repair of different metals.

[0005] Therefore, it is necessary to provide a nickel-based welding wire with high strength, good plasticity and toughness, and strong crack resistance, which is suitable for crack repair of iron-based materials under high stress conditions. Summary of the invention

[0006] The main technical problem solved by the present invention is to provide a nickel-based powder cored welding wire which can be welded under high stress conditions, and the weld obtained by welding has high strength and strong deformation resistance.

[0007] In order to solve the above technical problems, the present invention provides a nickel-based powder cored welding wire, comprising an outer skin and a powder core, wherein the outer skin wraps the powder core; the outer skin is a nickel-chromium alloy strip, and the composition of the powder core comprises: 1% to 8% metal chromium powder, 8% to 20% metal manganese, 2% to 20% metal molybdenum, 35% to 50% metal iron powder, 0% to 2% ferrotitanium powder, 0% to 3% ferrovanadium powder, <2% ferrosilicon powder, 3% to 8% ferroniobium powder, 2% to 6% fluorite, 1% to 3% rutile, 2% to 7% quartz, 3% to 8% marble, <3% feldspar, and the balance is metal nickel powder.

[0008] The beneficial effects of the present invention are as follows: the nickel-based powder-cored welding wire according to the embodiment of the present invention can be welded under high stress conditions, and the weld obtained by welding has high strength and strong plasticity and toughness. DETAILED DESCRIPTION

[0009] The nickel-based powder cored welding wire of the embodiment of the present invention comprises an outer skin and a powder core, wherein the outer skin wraps the powder core. The outer skin is a nickel-chromium alloy strip, and the composition of the outer skin is: Cr (19% to 21%) and Ni (67% to 81%), wherein the impurity content is less than 2%, and the above percentages are weight percentages.

[0010] The composition of the powder core is: 1% to 8% metal chromium powder, 8% to 20% metal manganese, 2% to 20% metal molybdenum, 35% to 50% metal iron powder, 0% to 2% ferrotitanium powder (Ti, 30% to 50%; Fe, balance), 0% to 3% ferrovanadium powder (V, 50%; Fe, balance), ferrosilicon powder <2% (S, 70%; Fe, balance), 3% to 8% ferroniobium powder (Nb, 30% to 50%; Fe, balance), 2% to 6% fluorite, 1% to 3% rutile, 2% to 7% quartz, 3% to 8% marble, <3% feldspar, balance is metal nickel powder. The weight coefficient of the powder core is 24% to 33%. Among them, the weight coefficient is also called the filling rate, which refers to the ratio of the weight of the powder core to the weight of the welding wire per unit length.

[0011] Among them, metal molybdenum can be added in the form of metal molybdenum powder; metal molybdenum powder can also be replaced or partially replaced by ferromolybdenum powder. If ferromolybdenum powder is added to the powder core, the added iron powder will be reduced accordingly. Metal manganese can be added in the form of metal manganese powder. The purity of metal chromium powder, metal nickel powder, metal manganese powder, metal molybdenum powder, metal iron powder, etc. is higher than 99.5%; the purity of the alloy components in ferromolybdenum powder, ferrotitanium powder, ferrovanadium powder, ferrosilicon powder, and ferroniobium powder is higher than 97%.

[0012] Mineral powders such as fluorite, rutile, quartz, marble, and feldspar are used to form slag to protect the welding layer, improve the performance of the welding layer and the welding performance at various positions. During the welding operation, only part of the alloy elements transition to the weld, and most of them form slag shells and fall off.

[0013] The alloy composition of the welding wire is related to the chemical composition of the repaired part and the welding position. If the part has a high Cr content and high strength, the Cr and Fe contents in the welding wire will be reduced accordingly, so that the alloy element content in the weld reaches the optimal range. By increasing the Ni content in the welding wire, the plasticity of the weld is improved and the crack resistance is improved. If the S content in the part is high, the Mn and fluorite content in the welding wire will be increased to eliminate the heat marks caused by S. For example, if a type of workpiece is mainly repaired by flat welding, the amount of mineral powder added can be appropriately reduced to increase the proportion of metal powder and improve the deposition efficiency. Otherwise, the mineral powder can be added normally to ensure the welding quality.

[0014] The alloy system of powder cored welding wire is a solid solution strengthened alloy, and large hard particles (precipitation phase) are avoided in the alloy. The role of adding powder in the welding process and weld performance is as follows:

[0015] Cr improves the corrosion resistance and oxidation resistance of the alloy. The oxide Cr2O3 formed by Cr can protect the alloy from further oxidation. At the same time, it can improve the strength of the Ni-based alloy with a small reduction in toughness.

[0016] Fe increases the strength of Ni-based alloys, reduces the amount of Ni used, and reduces costs, but adding too much reduces toughness.

[0017] Mo improves the strength of Ni-based alloys and enhances the corrosion resistance of the alloys. However, it is costly and excessive addition can easily form harmful precipitation phases. Therefore, it is not advisable to add too much.

[0018] Nb improves the strength of Ni-based alloys, but easily forms carbides with C, reducing toughness, and the amount of addition needs to be controlled.

[0019] Mn and Si increase the strength of Ni-based alloys. They form composite oxides with oxygen, reduce the oxygen content in the weld, reduce oxide inclusions, and improve the toughness of the alloy. Mn and S can form compounds, reduce the cracking tendency caused by S, and improve the strength and toughness of the alloy.

[0020] Ti, V and C form fine compound particles to prevent Cr and C from forming large-sized carbides, thereby improving the strength and maintaining the toughness of the alloy.

[0021] S and P are impurities, the less the better.

[0022] The main component of fluorite is CaF2, which is used to produce slag, reduce the viscosity of the slag, improve the slag removal, reduce the hydrogen in the weld, and improve the weld's resistance to hydrogen embrittlement and toughness.

[0023] The main component of rutile is TiO2, which plays the role of stabilizing the arc and forming slag.

[0024] Marble is mainly composed of CaCO3, which can form slag and gas, and bring slag-gas combined protection to the welding layer. It decomposes CaO when heated, adjusts the acidity and alkalinity of the slag, and improves the slag removal performance.

[0025] Quartz is mainly SiO2, which is used for slag making, adjusting the acidity and alkalinity of slag, and improving the protection and slag removal properties of slag.

[0026] The components of feldspar include SiO2, Al2O3, K2O, and Na2O, which play the role of stabilizing the arc and forming slag.

[0027] When preparing the powder core, the powder is mixed evenly and placed in an environment of 120-130° C. for 3-5 hours before processing the wire material. Among them, more than 90% of the particle size of the powder is between 60 and 325 meshes.

[0028] The mass ratio of the powder core to the entire powder core welding wire is called the weight coefficient. In the embodiment of the present invention, the weight coefficient of the powder core is 24% to 33%, and the diameter of the powder core welding wire is 1.2 mm to 1.6 mm.

[0029] The powder cored wire is welded by means of gas shielding the melting electrode, the shielding gas can be pure Ar (purity 99.9%), or a mixture of Ar and CO2 or a mixture of Ar and O2, wherein the volume ratio of CO2 or O2 in the mixture is 2%.

[0030] Since the damaged position of steel components is not fixed, welding in all positions is often encountered. To meet this demand, a slag shell must be formed when the weld is formed to protect the weld, reduce the flow of the liquid molten pool, improve the weld formation during vertical welding, horizontal welding and overhead welding, and reduce defects. The viscosity of the slag shell is greater than that of the molten pool, which constrains the liquid state and prevents it from flowing away under the action of gravity, thereby forming a continuous and full weld.

[0031] Embodiment 1: The weight coefficient of the powder core in the powder core welding wire is 27%, the diameter of the powder core welding wire is 1.2mm, and the outer skin of the powder core welding wire is NiCr20 strip. The composition of the powder core includes: 8% metal chromium powder, 15% metal manganese powder, 20% metal molybdenum powder, 38% metal Fe powder, 1% ferrotitanium powder, 3% ferrovanadium powder, 1.8% ferrosilicon powder, 7% ferroniobium powder, 5% fluorite, 3% rutile, 3% quartz, 3% marble, 2% feldspar, and the balance is metal nickel powder. When welding the powder core welding wire of this embodiment, gas shielding melting electrode is adopted for welding, and the shielding gas is a mixture of Ar and CO2. The weld obtained by welding in the above manner has good slag removal, good forming, good crack resistance, and is suitable for all-position welding.

[0032] During welding, the slag shell adheres to the surface of the weld, reducing the O and H content in the weld, which can significantly reduce the generation of pores and cracks, and is beneficial to improving the strength and toughness of the weld. In addition, since the viscosity of the slag shell is lower than that of the liquid metal, under the coating of the slag shell, the liquid metal will not flow everywhere during vertical welding or overhead welding, and the weld is well formed. The room temperature tensile strength of the weld obtained by welding with the powder cored welding wire of this embodiment reaches 600-650MPa, the yield strength is 400-470MPa, and the elongation after fracture is greater than 45%. For example, the general ball mill shell material is mostly Q235C steel, whose room temperature tensile strength is 370-500MPa, the yield strength is 185-235MPa, and the elongation after fracture is 21%-26%. When the powder cored welding wire of this embodiment is used to repair the cracks of the ball mill shell, the mechanical properties of the obtained weld are better than those of the base material, and even in the case of high stress, the mechanical properties of the weld are fully abundant.

[0033] If the slag shell powder is not formed properly, the mechanical properties of the weld cannot reach the above values, and it is not suitable for use under high stress conditions. In addition, the slag shell should not only have a good protective effect on the weld, but also be conducive to slag removal and easy to remove.

[0034] Embodiment 2: The weight coefficient of the powder core in the powder core welding wire is 30%, the diameter of the powder core welding wire is 1.6mm, and the outer skin of the powder core welding wire is NiCr20 strip. The composition of the powder core includes: 6% metal chromium powder, 10% metal manganese powder, 15% metal molybdenum powder, 32% metal iron powder, 1.5% ferrotitanium powder, 2.5% ferrovanadium powder, 1.5% ferrosilicon powder, 5% ferroniobium powder, 3% fluorite, 1.5% rutile, and the balance is metal nickel powder. When welding the powder core welding wire of this embodiment, gas shielding melting electrode is adopted, and the shielding gas is a mixture of Ar and CO2. The weld obtained by welding with the powder core welding wire of this embodiment has only a small amount of slag, is suitable for flat welding, has good forming, good crack resistance, and higher deposition efficiency than 1.2mm welding wire.

[0035] The room temperature tensile strength of the weld obtained by using the powder cored welding wire of this embodiment reaches 570-630 MPa, the yield strength reaches 380-450 MPa, and the elongation after fracture is greater than 30%.

[0036] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A nickel-based powder cored welding wire, comprising an outer sheath and a powder core, wherein the outer sheath wraps the powder core; the outer sheath is a nickel-chromium alloy strip, characterized in that: The composition of the powder core includes: 1% to 8% metal chromium powder, 8% to 20% metal manganese, 2% to 20% metal molybdenum, 35% to 50% metal iron powder, 0% to 2% ferrotitanium powder, 0% to 3% ferrovanadium powder, <2% ferrosilicon powder, 3% to 8% ferroniobium powder, 2% to 6% fluorite, 1% to 3% rutile, 1% to 3% quartz, 3% to 8% marble, <3% feldspar, and the balance is metal nickel powder.

2. The nickel-based powder cored welding wire according to claim 1, characterized in that: The composition of the outer skin includes 19% to 21% chromium and 67% to 81% nickel.

3. The nickel-based powder cored welding wire according to claim 1, characterized in that: The composition ratio of ferrotitanium powder is: Ti, 30-50%; Fe, the balance.

4. The nickel-based powder cored welding wire according to claim 1, characterized in that: The composition ratio of ferrovanadium powder is: V, 50%; Fe, the balance.

5. The nickel-based powder cored welding wire according to claim 1, characterized in that: The composition ratio of ferrosilicon powder is: S, 70%; Fe, the balance.

6. The nickel-based powder cored welding wire according to claim 1, characterized in that: The composition ratio of ferroniobium powder is: Nb, 30-50%; Fe, the balance.

7. The nickel-based powder cored welding wire according to claim 1, characterized in that: More than 90% of the particle sizes of the powder in the powder core are between 60 and 325 meshes.

8. The nickel-based powder cored welding wire according to claim 1, characterized in that: In nickel-based powder cored welding wire, the weight coefficient of the powder core is 24% to 33%.

9. The nickel-based powder cored welding wire according to claim 1, characterized in that: The diameter of nickel-based powder cored welding wire is 1.2mm to 1.6mm.