阅读说明：本技术 适用于全位置焊接的超低温高锰钢用药芯焊丝及其应用 (Flux-cored wire for ultralow-temperature high manganese steel suitable for all-position welding and application thereof ) 是由 陈成 汪昌红 包润新 汪涛 于 2021-07-20 设计创作，主要内容包括：本发明涉及焊接材料技术领域,尤其涉及一种适用于全位置焊接的超低温高锰钢用药芯焊丝及其应用；该药芯焊丝包括碳钢钢带和药芯,碳钢钢带为SPCC钢带,药芯中各组分及其在药芯中所占的质量百分比含量为：大理石2～6％,钛酸钾2～6％,氟化钠0.5～2.5％,金属锰60～70％,金属铬6～8％,氮化铬铁4～8％,镍粉8～12％,钼粉2～6％,钒铁1～2％,铜粉1～2％,氧化铋0.2～0.4％,石墨0.5～1.5％,余量为铁粉,药芯焊丝在焊接时的保护气体为：80％Ar+20％CO-(2)的混合气。本发明提供的药芯焊丝,采用低成本的C-Mn-Cr-Ni-N合金体系设计,在-196℃及更低温度下力学性能优异,能显著降低成本,且能实现全位置焊接,焊接接头综合性能好。(The invention relates to the technical field of welding materials, in particular to a flux-cored wire for ultralow-temperature high-manganese steel suitable for all-position welding and application thereof; the flux-cored wire comprises a carbon steel strip and a flux core, wherein the carbon steel strip is an SPCC steel strip, and the flux core comprises the following components in percentage by mass: 2-6% of marble, 2-6% of potassium titanate, 0.5-2.5% of sodium fluoride, 60-70% of manganese metal, 6-8% of chromium metal, 4-8% of chromium nitride, 8-12% of nickel powder, 2-6% of molybdenum powder, 1-2% of ferrovanadium, 1-2% of copper powder, 0.2-0.4% of bismuth oxide, 0.5-1.5% of graphite and the balance of iron powder, wherein the protective gas of the flux-cored wire during welding is as follows: 80% Ar + 20% CO 2 The mixed gas of (1). The flux-cored wire provided by the invention adopts a low-cost C-Mn-Cr-Ni-N alloy system design, has excellent mechanical property at the temperature of-196 ℃ and lower, can obviously reduce the cost, can realize all-position welding, and is a welding joint healdThe combination property is good.)

1. The flux-cored wire for the ultralow-temperature high-manganese steel suitable for all-position welding comprises a carbon steel strip and a flux core, and is characterized in that the flux core comprises the following components in percentage by mass: 2-6% of marble, 2-6% of potassium titanate, 0.5-2.5% of sodium fluoride, 60-70% of manganese metal, 6-8% of chromium metal, 4-8% of ferrochromium nitride, 8-12% of nickel powder, 2-6% of molybdenum powder, 1-2% of ferrovanadium, 1-2% of copper powder, 0.2-0.4% of bismuth oxide, 0.5-1.5% of graphite and the balance of iron powder.

2. The flux-cored welding wire for the ultralow-temperature high-manganese steel suitable for all-position welding according to claim 1, wherein the mass of the flux core accounts for 35-45% of the total mass of the flux-cored welding wire.

3. The flux-cored welding wire for ultra-low temperature high manganese steel suitable for all-position welding of claim 1, wherein TiO in potassium titanate₂Is 50-60% by mass, K₂The mass percent of O is 17-19%.

4. The flux-cored welding wire for ultra-low temperature high manganese steel suitable for all-position welding of claim 1, wherein the mass percent of Cr in the ferrochromium nitride is more than 60%, and the mass percent of N is more than 5%.

5. The flux-cored welding wire for ultra-low temperature high manganese steel suitable for all-position welding of claim 1, wherein the mass percentage of V in the ferrovanadium is more than 50%.

6. The flux-cored welding wire for ultra-low temperature high manganese steel suitable for all-position welding of claim 1, wherein the carbon steel strip is an SPCC steel strip.

7. The method for applying the flux-cored wire for the ultralow-temperature high manganese steel suitable for all-position welding in any one of claims 1 to 6, wherein the shielding gas of the flux-cored wire during welding is 80% Ar and 20% CO₂The mixed gas of (1).

8. The application method of the flux-cored wire for the ultralow-temperature high manganese steel suitable for all-position welding according to claim 7, characterized in that the flux-cored wire has a welding current of 200-220A and a welding voltage of 28-30V when welding at a flat welding position.

9. The application method of the flux-cored wire for the ultralow-temperature high manganese steel suitable for all-position welding according to claim 7, characterized in that the flux-cored wire has a welding current of 160-180A and a welding voltage of 26-28V when welding at a transverse welding position.

10. The application method of the flux-cored wire for the ultralow-temperature high manganese steel suitable for all-position welding according to claim 7, characterized in that the flux-cored wire has a welding current of 120-140A and a welding voltage of 22-24V when welding is carried out at a vertical welding position and an overhead welding position.

Technical Field

The invention relates to the technical field of welding materials, in particular to a flux-cored wire for ultralow-temperature high-manganese steel suitable for all-position welding and application thereof.

Background

With the development of modern industry, the world energy consumption is more and more concentrated on gaseous energy, particularly natural gas which is clean, convenient and efficient advanced energy, the working temperature of the low-temperature steel for storing and transporting Liquefied Natural Gas (LNG) is-196 ℃, the largest amount of used steel is 9Ni steel, and the smelting and using cost of the 9Ni steel is greatly increased due to the high price of nickel element.

The ultralow-temperature high-manganese steel and the 9Ni steel have the same physical metallurgical characteristics, have the advantages of high performance (excellent crack resistance) and low cost, are the best competitive materials for the steel for the LNG storage tank instead of the 9Ni steel in the future, and have become research hotspots in various countries in the world. In the face of the huge market demand of the ultralow-temperature high-manganese steel, the welding material which can be matched with the ultralow-temperature high-manganese steel and has good welding process performance, mechanical performance and service performance has a very good market prospect, the welding positions most applied in the manufacturing process of the LNG storage tank are 3G (vertical welding) positions and 4G (overhead welding) positions, and the welding material required to be used is suitable for all-position welding. At present, flux-cored wires for ultralow-temperature high-manganese steel suitable for all-position welding are not seen in the market, and the flux-cored wires are one of the bottlenecks in realizing high-efficiency welding of the ultralow-temperature high-manganese steel.

Disclosure of Invention

In order to solve the problems, the invention provides a flux-cored wire for ultralow-temperature high manganese steel suitable for all-position welding, which comprises a carbon steel strip and a flux core, wherein the flux core comprises the following components in percentage by mass: 2-6% of marble, 2-6% of potassium titanate, 0.5-2.5% of sodium fluoride, 60-70% of manganese metal, 6-8% of chromium metal, 4-8% of ferrochromium nitride, 8-12% of nickel powder, 2-6% of molybdenum powder, 1-2% of ferrovanadium, 1-2% of copper powder, 0.2-0.4% of bismuth oxide, 0.5-1.5% of graphite and the balance of iron powder.

Preferably, the mass of the flux core accounts for 35-45% of the total mass of the flux-cored wire.

Preferably, TiO in the potassium titanate₂Is 50-60% by mass, K₂The mass percent of O is 17-19%.

Preferably, the mass percent of Cr in the ferrochrome nitride is more than 60%, and the mass percent of N is more than 5%.

Preferably, the mass percentage of V in the ferrovanadium is more than 50%.

Preferably, the carbon steel strip is an SPCC steel strip.

The flux-cored wire for ultralow-temperature high manganese steel suitable for all-position welding provided by the invention is worthy of being manufactured by adopting a conventional flux-cored wire manufacturing process.

The invention also provides a method for applying the flux-cored wire for the ultralow-temperature high manganese steel suitable for all-position welding, and the protective gas of the flux-cored wire during welding is 80% Ar and 20% CO₂The mixed gas of (1).

Further, when the flux-cored wire is used for welding at a flat welding position, the welding current is 200-220A, and the welding voltage is 28-30V.

Furthermore, when the flux-cored wire is used for welding at a transverse welding position, the welding current is 160-180A, and the welding voltage is 26-28V.

Further, the welding current of the flux-cored wire is 120-140A when the flux-cored wire is used for welding at the vertical welding position and the overhead welding position, and the welding voltage is 22-24V.

The design principle of the flux-cored wire for ultralow-temperature high manganese steel suitable for all-position welding is as follows: through the design of a low-cost C-Mn-Cr-Ni-N component system and the transition of metal powder core alloy, the Mn content in the formed weld metal is 20-25%, and the mechanical property is excellent at the temperature of-196 ℃ and lower. The invention contains proper amount of potassium titanate, which can ensure the stability of welding electric arc and has good all-position welding process applicability; the austenite structure is further stabilized by adding a proper amount of Ni and N, so that the strength and the low-temperature impact toughness of the weld metal are improved; cr and Mo can form carbide or nitride to improve the strength of welding seams, and Mo can also reduce a solid-liquid coexisting region and effectively inhibit the generation of thermal cracks; by adding trace alloying elements such as V, Cu, the grains of weld metal can be refined, so that the strength and toughness of weld metal can be improved, and the crack resistance of weld metal can be improved.

The main component of marble is CaCO₃The main function of the welding arc welding device is to improve the welding arc stiffness, greatly reduce the dispersion degree of the arc during argon-rich gas shielded welding and improve the welding penetration and the fusion of base metal; the addition amount of the traditional Chinese medicine core is less than 2% of the total amount of the components is about 6%, the welding arc is dispersed, the penetration depth is shallow, poor fusion between the weld joint and the base metal is easy to cause, and the spatter is increased.

The main component of potassium titanate is TiO₂And K₂O, plays a role in slagging and arc stabilization, reduces welding spatter, improves slag fluidity and coverage, and is beneficial to the all-position welding process of the welding wire; the addition amount of potassium titanate is preferably 2-6%, and the addition amount is too low, so that the welding arc stability and the all-position welding manufacturability are poor.

The sodium fluoride has a lower melting point, can reduce the eutectic point of the slag, reduce the viscosity and the surface tension of the slag, and is favorable for improving the slag detachability of the welding seam and the surface forming of the welding seam; the sodium fluoride is decomposed at high temperature to generate HF gas, so that the effects of removing hydrogen from a welding seam and improving the indentation resistance are achieved, when the addition amount is more than 2.5%, welding spatter is increased, molten slag becomes thin, and the all-position welding process of the welding wire is poor; when the addition amount is less than 0.5%, the dehydrogenation ability is insufficient and pore indentation is likely to occur.

Mn in the metal manganese is an element for expanding an austenite region and stabilizing an austenite structure, when the content of Mn in the weld metal is more than 20 percent, a complete austenite structure can be formed, the low-temperature brittle transition temperature disappears, and the low-temperature impact toughness of the weld metal is improved; the manganese metal can also participate in deoxidation and is used for reducing the oxygen content of weld metal and increasing the strength and crack resistance of the weld metal, and the optimal addition amount of the manganese metal is 60-70%.

Cr in the metal chromium and the chromium nitride iron can form carbide with C, so that dispersion strengthening and solid solution strengthening effects are achieved, and the metal strength of the welding line is improved; n is an element for expanding an austenite region and stabilizing an austenite structure, and can improve the low-temperature impact toughness of the weld metal; meanwhile, as a solid solution strengthening element, the metal can form nitrides with Cr, Mo and V, so that the strength of the weld metal can be improved without obviously damaging the plasticity and toughness of the weld metal; the addition amount of the metal chromium is preferably 6-8%, and the addition amount of the chromium iron nitride is preferably 4-8%.

Ni in the nickel powder is an element for forming and stabilizing an austenite structure, so that the brittle transition temperature can be reduced, and the strength and the low-temperature impact toughness of weld metal can be improved.

Mo in the molybdenum powder can form carbide or nitride to improve the strength of a welding seam, and the Mo can also reduce a solid-liquid coexisting interval and can effectively inhibit the occurrence of thermal cracks.

V is a strong carbide forming element, can form special carbide, refines austenite grains and improves the metal strength and toughness of the welding seam.

Cu is a solid solution strengthening and precipitation strengthening element, and can improve the strength of weld metal; when the amount of the copper powder is more than 2%, the cracking resistance is not good, and the amount of the copper powder is preferably 1 to 2%.

The bismuth oxide has the function of improving slag detachability, and the addition amount of the bismuth oxide is preferably 0.2-0.4%.

C is an austenitizing element, and simultaneously can form carbide with Cr, Mo and V to improve the strength of the austenitic weld metal.

The ultralow-temperature high manganese steel deposited metal welded by the method comprises the following chemical components: c: 0.3-0.45%, Si is less than or equal to 0.5%, Mn: 20-25%, Cr: 2-6%, Ni: 2-6%, Mo: 0.5-2.0%, Cu: 0.1-0.2%, N: 0.1-0.2%, V is less than or equal to 0.2%, S is less than or equal to 0.015%, and P is less than or equal to 0.015%.

When the content of C in deposited metal is less than 0.3%, the strength of the welding seam cannot meet the requirement; when the content of C in the deposited metal is more than 0.45%, cracks may occur during welding and the impact toughness may be lowered.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following beneficial effects:

1) the flux-cored wire provided by the invention adopts a low-cost C-Mn-Cr-Ni-N alloy system design and uses metal powder-core alloy for transition, the Mn content in the formed weld metal is 20-25%, the mechanical property is excellent at minus 196 ℃ and lower temperature, the Ni content of the matched welding material is obviously reduced, and the use cost is greatly reduced;

2) the flux-cored wire provided by the invention has good comprehensive performance of deposited metal and a welding joint, and the tensile strength is more than or equal to 700 MPa; the yield strength is more than or equal to 500 MPa; the elongation is more than or equal to 30 percent; under the condition of-196 ℃, Akv is more than or equal to 80J;

3) the flux-cored wire provided by the invention has excellent welding process performance, is suitable for all-position welding, and has wide applicability.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, belong to the scope of protection of the present invention.

The invention provides a flux-cored wire for ultralow-temperature high-manganese steel suitable for all-position welding, which comprises a carbon steel strip and a flux core, wherein the carbon steel strip is preferably an SPCC steel strip, the mass of the flux core is 35-45% of the total mass of the flux-cored wire, and the flux core comprises the following components in percentage by mass: 2-6% of marble, 2-6% of potassium titanate, 0.5-2.5% of sodium fluoride, 60-70% of manganese metal, 6-8% of chromium metal, 4-8% of ferrochromium nitride, 8-12% of nickel powder, 2-6% of molybdenum powder, 1-2% of ferrovanadium, 1-2% of copper powder, 0.2-0.4% of bismuth oxide, 0.5-1.5% of graphite and the balance of iron powder.

Further, TiO in the potassium titanate₂Is 50-60% by mass, K₂The mass percent of O is 17-19%.

Further, the mass percent of Cr in the ferrochrome nitride is more than 60%, and the mass percent of N is more than 5%.

Further, the mass percent of V in the ferrovanadium is more than 50%.

The flux-cored wire for ultralow-temperature high manganese steel suitable for all-position welding provided by the invention is worthy of being manufactured by adopting a conventional flux-cored wire manufacturing process.

The welding method using the flux-cored wire comprises the following steps of adopting 80% Ar and 20% CO₂The mixed gas is protective gas, when welding is carried out at a flat welding position, the welding current is 200-220A, and the welding voltage is 28-30V; when welding is carried out at the transverse welding position, the welding current is 160-180A, and the welding voltage is 26-28V; the welding current is 120-140A and the welding voltage is 22-24V when welding is carried out at the vertical welding position and the overhead welding position.

The invention is further illustrated by specific examples:

examples 1 to 3 are flux-cored wires with different formulas in 3, the numbers are No. 1, No. 2 and No. 3, Table 1 is the evaluation of flux-cored formulas and welding process performance, Table 2 is the mechanical property of deposited metal of the flux-cored wires, and Table 3 is the chemical composition table of the deposited metal.

TABLE 1 flux core formulation (mass percent) and welding process performance

Example numbering	1#	2#	3#
				Marble	4	4	3
Potassium titanate	5	4	2
				Sodium fluoride	0.5	1	1.3
Manganese metal	63	60	65
				Metallic chromium	6.5	7	6
Chromium iron nitride	4.5	6	7
				Nickel powder	9	11	8
Molybdenum powder	3	2	4
				Vanadium iron	1.5	1	1.5
Copper powder	1.5	2	1
				Bismuth oxide	0.3	0.4	0.2
Graphite	0.6	1.2	1
				Iron powder	0.6	0.4	0
Filling rate of the drug core	40	38	42
				Evaluation of welding Process Properties	Good effect	Good effect	In general

TABLE 2 mechanical Properties of deposited metals

TABLE 3 chemical composition of deposited metal

As can be seen from tables 1, 2 and 3, the flux-cored wire for all-position welded ultra-low temperature high manganese steel according to the present invention has the following comprehensive properties: the tensile strength is more than or equal to 700 MPa; the yield strength is more than or equal to 500 MPa; the elongation is more than or equal to 30 percent; under the condition of-196 ℃, Akv is more than or equal to 80J; the all-position welding process has excellent performance, and can completely meet the mechanical property requirement and the welding position requirement of the ultralow-temperature high-manganese steel.

It should be understood by those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Although an embodiment of the present invention has been described, it is to be understood that the present invention should not be limited to this embodiment, and variations and modifications can be made by those skilled in the art within the spirit and scope of the present invention as defined in the appended claims.