Nickel-based cored welding wire

Abstract

The application discloses a nickel-based powder core welding wire, which comprises an outer skin and a powder core, wherein the outer skin is wrapped around the powder core; the outer skin is a nickel-chromium alloy strip; and the powder core is composed of the following components: 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 titanium-iron powder, 0-3% of vanadium-iron powder, <2% of silicon-iron powder, 3-8% of niobium-iron powder, 2-6% of fluorite, 1-3% of rutile, 1-3% of quartz, 3-8% of marble, <3% of feldspar, and the balance of metal nickel powder. The nickel-based powder core welding wire is suitable for welding under high stress conditions, and the welding seam obtained thereby is not prone to cracking and has high plasticity and toughness.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding technology, in particular to a nickel-based flux-cored wire for welding under high stress conditions. BACKGROUND

[0002] The production time of large heavy equipment is generally 2-6 years, and the price is high. If new equipment is used to replace old equipment, the end user will face very high costs and will generally not choose to replace new equipment, so maintenance and prolongation of service life are the only choice to extend the service life of old equipment.

[0003] Large heavy equipment is basically made of steel (iron-based alloy) materials, and 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. In the repair process, the high stress working condition puts high requirements on the performance of the weld. If iron-based alloy welding material is 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 DEG C before welding, and the welding process needs to be maintained in this temperature range. The working environment of the welder is very poor. In addition, many times are high-altitude operations, the labor intensity is high, and the risk of accidents is high. Using high crack resistance nickel-based alloy repair can be constructed almost without preheating, and the weld does not crack, which can meet the repair strength requirements. This is because the crystal structure of nickel-based alloy is only one form of face-centered cubic, which will not change phase during welding, forming a hard and brittle phase, avoiding the cracking of most iron-based alloy welding. In addition, the nickel-based alloy with solid solution strengthening has multiple slip systems and high deformation capacity under high stress, and will not crack due to high stress.

[0004] Most existing nickel-based alloy wires are solid wires, which are difficult to form and prone to defects when performing all-position welding by gas shielded arc welding. By adding mineral powder to the flux-cored wire, an effective slag shell is formed on the surface of the molten pool, which not only improves the forming, but also reduces the defects. In addition, the composition of the solid wire is fixed and cannot completely adapt to the repair of different component metals. Especially when the S element content in the base metal is high, the nickel-based alloy weld is prone to defects. The alloy elements provided by the present application are adjusted according to the composition of the repaired metal, and the content of Mn and Mo elements is increased to reduce the influence of harmful elements such as S, so that the welding wire is 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

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

[0007] To solve the above technical problems, the present application provides 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 strip, and the composition of the powder core comprises: 1-8% of metal chromium powder, 8-20% of metal manganese, 2-20% of metal molybdenum, 35-50% of metal iron powder, 0-2% of titanium-iron powder, 0-3% of vanadium-iron powder, <2% of silicon-iron powder, 3-8% of niobium-iron powder, 2-6% of fluorite, 1-3% of rutile, 2-7% of quartz, 3-8% of marble, <3% of feldspar, and the balance of metal nickel powder.

[0008] The embodiment of the present application can weld under high stress conditions, and the weld strength is high and the plasticity and toughness are strong. DETAILED DESCRIPTION

[0009] The nickel-based powder core welding wire of the embodiment of the present application comprises an outer skin and a powder core, and 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 (19-21%) and Ni (67-81%), wherein the impurity content is <2%, and the above percentages are weight percentages.

[0010] The composition of the powder core is: 1-8% of metal chromium powder, 8-20% of metal manganese, 2-20% of metal molybdenum, 35-50% of metal iron powder, 0-2% of titanium-iron powder (Ti, 30-50%; Fe, balance), 0-3% of vanadium-iron powder (V, 50%; Fe, balance), <2% of silicon-iron powder (S, 70%; Fe, balance), 3-8% of niobium-iron powder (Nb, 30-50%; Fe, balance), 2-6% of fluorite, 1-3% of rutile, 2-7% of quartz, 3-8% of marble, <3% of feldspar, and the balance of metal nickel powder. The weight coefficient of the powder core is 24-33%. 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] The metal molybdenum can be added in the form of metal molybdenum powder; the metal molybdenum powder can also be replaced or partially replaced by molybdenum-iron powder, and if the molybdenum-iron powder is added to the powder core, the iron powder is correspondingly reduced. The metal manganese can be added in the form of metal manganese powder. The purity of the metal chromium powder, the metal nickel powder, the metal manganese powder, the metal molybdenum powder, and the metal iron powder is higher than 99.5%; the purity of the alloy components in the molybdenum-iron powder, the titanium-iron powder, the vanadium-iron powder, the silicon-iron powder, and the niobium-iron powder is higher than 97%.

[0012] The mineral powder of fluorite, rutile, quartz, marble, and feldspar is used to form a slag protection welding layer, improve the welding layer performance and the welding performance at various positions, and only part of the alloy elements is transferred to the weld in the welding operation, and most of them form a slag shell 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 are correspondingly reduced to make the alloy element content in the weld reach the optimal range. By increasing the Ni content in the welding wire, the plasticity and crack resistance of the weld are improved. If the part has a high S content, the Mn and fluorite contents in the welding wire are increased to eliminate hot cracking caused by S. If the workpiece is mainly repaired by flat welding, the addition amount of mineral powder can be appropriately reduced, the metal powder ratio is increased, and the deposition efficiency is improved. Otherwise, the mineral powder is normally added to ensure the welding quality.

[0014] The alloy system of the flux-cored wire is a solid solution strengthening alloy, and large-sized hard particles (precipitates) are avoided in the alloy. The effects of the added powder in the welding process and in the weld performance are 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 and can also improve the strength of the Ni-based alloy with a small decrease in toughness.

[0016] Fe improves the strength of the Ni-based alloy, reduces the use amount of Ni, and reduces the cost, but too much addition reduces the toughness.

[0017] Mo improves the strength of the Ni-based alloy and enhances the corrosion resistance of the alloy, but excessive addition easily forms harmful precipitates, so it is not suitable to be added too much.

[0018] Nb improves the strength of the Ni-based alloy, but easily forms carbides with C, which reduces the toughness, so the addition amount needs to be controlled.

[0019] Mn and Si improve the strength of the Ni-based alloy. Both of them form complex oxides with oxygen, which reduces the oxygen content in the weld and reduces the oxide inclusions, thereby improving the toughness of the alloy. Mn and S can form compounds to reduce the cracking tendency caused by S and improve the strength and toughness of the alloy.

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

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

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

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

[0024] Marble is mainly CaCO3, which is used for slagging and gas making, and brings slag-gas combined protection to the welding layer. CaO is decomposed by heat, which adjusts the acid-base property of the slag and improves the slag detachability.

[0025] Quartz is mainly SiO2, which is used for slagging, adjusting the acid-base property of the slag, improving the protection property and the slag detachability of the slag.

[0026] Feldspar has components of SiO2, Al2O3, K2O and Na2O, which plays a role in stabilizing arc and slagging.

[0027] In the preparation of the powder core, the powder is mixed uniformly and then placed in an environment of 120-130℃ for 3-5 hours before the processing of the wire. The particle size of the powder is more than 90% between 60-325 mesh.

[0028] The mass ratio of the powder core to the whole powder core welding wire becomes the weight coefficient, which is 24%-33% in the embodiment of the present application, and the diameter of the powder core welding wire is 1.2mm-1.6mm.

[0029] The powder core welding wire is welded by the way of gas protection melting electrode, and the protection gas can be pure Ar (purity 99.9%), or the mixed gas of Ar and CO2, or the mixed gas of Ar and O2, wherein the volume ratio of CO2 or O2 in the mixed gas is 2%.

[0030] Since the damage position of the steel member is not fixed, the all-position welding is often encountered. In order to meet this requirement, the slag shell must be formed when the weld is formed for protecting the weld, reducing the flow of the liquid molten pool, improving the weld forming in vertical welding, horizontal welding and overhead welding, and reducing defects. The viscosity of the slag shell is larger than that of the molten pool, which restricts the liquid form and prevents it from flowing away under the action of gravity, so that a continuous and full weld is formed.

[0031] In the embodiment one, 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 adopts NiCr20 strip. The composition of the powder core includes: metal chromium powder 8%, metal manganese powder 15%, metal molybdenum powder 20%, metal Fe powder 38%, titanium-iron powder 1%, vanadium-iron powder 3%, silicon-iron powder 1.8%, niobium-iron powder 7%, fluorite 5%, rutile 3%, quartz 3%, marble 3%, feldspar 2%, and the rest is metal nickel powder. In the welding operation of the powder core welding wire in the embodiment, the welding is carried out by the way of gas protection melting electrode, and the protection gas is the mixed gas of Ar and CO2. The weld obtained by the above welding has good slag detachability, good forming, good anti-cracking performance, and is suitable for all-position welding.

[0032] When welding, the slag shell adheres to the surface of the weld, reduces the content of O and H in the weld, can significantly reduce the generation of pores and cracks, is beneficial to improve the strength and toughness of the weld, and in addition, because the viscosity of the slag shell is lower than that of the liquid metal, under the covering of the slag shell, the liquid metal will not flow everywhere when vertical welding or overhead welding, and the weld is well formed. The tensile strength at room temperature of the weld obtained by welding the flux-cored wire of the embodiment is 600-650 MPa, the yield strength is 400-470 MPa, and the elongation after fracture is >45%. For example, the material of the general ball mill shell is generally steel of type Q235C, the tensile strength at room temperature is 370-500 MPa, the yield strength is 185-235 MPa, and the elongation after fracture is 21%-26%, and when the flux-cored wire of the embodiment is used to repair the cracks of the ball mill shell, the mechanical properties of the weld obtained are better than those of the base material, and even in the case of high stress, the mechanical properties of the weld are also sufficient.

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

[0034] Example 2: The weight coefficient of the powder core in the flux-cored wire is 30%, the diameter of the flux-cored wire is 1.6 mm, and the outer skin of the flux-cored wire is a NiCr20 strip. The composition of the powder core includes: 6% of metal chromium powder, 10% of metal manganese powder, 15% of metal molybdenum powder, 32% of metal iron powder, 1.5% of titanium-iron powder, 2.5% of vanadium-iron powder, 1.5% of silicon-iron powder, 5% of niobium-iron powder, 3% of fluorite, 1.5% of rutile, and the balance is metal nickel powder. When welding the flux-cored wire of the embodiment, the gas shielded metal arc welding method is used, and the protective gas is a mixture of Ar and CO2. The weld obtained by welding the flux-cored wire of the embodiment has only a small amount of slag, is suitable for flat welding, is well formed, has good anti-cracking performance, and has a higher deposition efficiency than 1.2 mm welding wire.

[0035] The tensile strength at room temperature of the weld obtained by the flux-cored wire of the embodiment is 570-630 MPa, the yield strength is 380-450 MPa, and the elongation after fracture is >30%.

[0036] The above only describes the embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the present application specification, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A nickel-based flux-cored welding wire comprising a sheath and a core, the sheath surrounding the core; the sheath being a nickel-chromium alloy strip, characterized in that, The composition of the core includes: 1-8% of metal chromium powder, 8-20% of metal manganese, 2-20% of metal molybdenum, 35-50% of metal iron powder, 1-2% of titanium iron powder, 3% of vanadium iron powder, 1.8%≤ silicon iron powder<2%, 3-8% of niobium iron powder, 2-6% of fluorite, 1-3% of rutile, 1-3% of quartz, 3-8% of marble, 2%≤ feldspar<3%, and the rest is metal nickel powder.

2. The nickel-based powder core welding wire of claim 1, wherein: The composition of the sheath includes 19-21% of chromium and 67-81% of nickel.

3. The nickel-based powder core welding wire of claim 1, wherein: The composition of the titanium iron powder is: Ti, 30-50%; Fe, the rest.

4. The nickel-based powder core welding wire of claim 1, wherein: The composition of the vanadium iron powder is: V, 50%; Fe, the rest.

5. The nickel-based powder core welding wire of claim 1, wherein: The composition of the silicon iron powder is: Si, 70%; Fe, the rest.

6. The nickel-based powder core welding wire of claim 1, wherein: The composition of the niobium iron powder is: Nb, 30-50%; Fe, the rest.

7. The nickel-based powder core welding wire of claim 1, wherein: The particle size of the powder in the core is 90% or more between 60-325 mesh.

8. The nickel-based powder core welding wire of claim 1, wherein: In the nickel-based core welding wire, the weight coefficient of the core is 24-33%.

9. The nickel-based powder core welding wire of claim 1, wherein: The diameter of the nickel-based core welding wire is 1.2-1.6 mm.