A seamless pipe core rod special high temperature resistant submerged arc wear-resistant flux-cored wire

Abstract

The present application belongs to the technical field of flux-cored wire, and relates to a seamless pipe core rod special high-temperature-resistant submerged arc wear-resistant flux-cored wire. The flux core comprises the following components in mass fraction: micro-carbon chromium iron 16-30 parts, metallic chromium 10-30 parts, zirconium sand 1-3 parts, cobalt powder 5-12 parts, nickel powder 10-20 parts, molybdenum powder 6-20 parts, rare earth ferrosilicon alloy 1-4 parts, niobium iron 2-6 parts, low-carbon manganese iron 4-8 parts, vanadium iron 2-6 parts, titanium iron 1-4 parts, chromium nitride 1.0-2.2 parts, and the rest is atomized iron powder. The filling ratio is 30-40%. The flux core of the present application replaces C with N to inhibit the formation of ferrite and improve the cold and hot fatigue resistance. At the same time, the chromium, molybdenum, cobalt, vanadium and other elements in the alloy form stable nitrides, which are dispersed in the deposited metal, thereby improving the high-temperature wear resistance, corrosion resistance and high-temperature hardness of the welding material, and the number of pipe penetrations is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of flux-cored welding wire technology and relates to a high-temperature resistant, submerged arc, and wear-resistant flux-cored welding wire for seamless mandrels. Background Technology

[0002] The mandrel is an essential tool for determining the pipe diameter and wall height in the rolling of seamless steel pipes, and it is also a major consumable component in continuous rolling mills. The mandrel operates under extremely harsh conditions during service, enduring frictional heat generated during rolling, thermal shock from the billet exceeding 1200°C, and the irritation of hot and cold water circulation. It also withstands significant radial rolling forces, as well as longitudinal tensile forces and surface friction forces generated by the relative movement between the billet and the mandrel along the length rolling direction. Therefore, the mandrel is prone to wear, cracking, and bending deformation during use. Once worn, the mandrel must be replaced to ensure the quality of the seamless pipe and the safety of the rolling mill.

[0003] Over 50% of the production and maintenance costs of continuous rolling mill equipment are spent on the consumption and replacement of mandrels, resulting in extremely high costs. Replaced mandrels can only be reused after being downsized or electroplated with hard chrome and repaired by welding, with welding repair currently being the most common method. Currently, the wear-resistant welding wire used for welding repair on the market is mainly solid 0Cr13Ni4Mo, with fewer types of flux-cored welding wires, and their alloy series are similar to those of solid welding wires. This alloy-based wear-resistant welding wire has a low tube insertion capacity; for example, for a 1000mm diameter mandrel, the insertion capacity is less than 1200. The reason for this is that ordinary wear-resistant welding wires have low high-temperature hardness, poor high-temperature wear resistance, and poor resistance to thermal cracking, making them unsuitable for welding repair of mandrels used in continuous rolling mill equipment. Therefore, developing a wear-resistant flux-cored welding wire with good high-temperature wear resistance and strong resistance to thermal cracking, specifically suitable for seamless tube mandrel repair and capable of significantly increasing the insertion capacity, is an urgent technical problem to be solved. Summary of the Invention

[0004] This invention addresses the problems existing in the mandrel surfacing process of traditional continuous rolling mill equipment by proposing a novel high-temperature resistant submerged arc wear-resistant flux-cored welding wire specifically for seamless tube mandrels.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] This invention provides a high-temperature resistant, submerged arc, and wear-resistant flux-cored welding wire specifically for seamless mandrels. Using this wire, the number of mandrels that can be threaded through a 1000mm diameter mandrel can reach over 2800. The flux core of this welding wire comprises the following components in parts by weight: 16-30 parts micro-carbon ferrochrome, 10-30 parts metallic chromium, 1-3 parts zircon sand, 5-12 parts cobalt powder, 10-20 parts nickel powder, 6-20 parts molybdenum powder, 1-4 parts rare earth ferrosilicon alloy, 2-6 parts ferroniobium, 4-8 parts low-carbon ferromanganese, 2-6 parts ferrovanadium, 1-4 parts ferrotitanium, 1.0-2.2 parts chromium nitride, with the balance being atomized iron powder, and a filling ratio of 30-40%. The outer sheath is made of low-carbon steel strip, model HS1 (technical parameters are as follows: C: <0.04%, Mn: 0.1-0.45%, Si: <0.04%, S: <0.02%, P: <0.022%, yield strength: 140-180Mpa, tensile strength: 280-360Mpa), with a thickness of 0.5-0.8mm and a width of 14-16mm. As the outer coating of the welding wire, after degreasing and drying, it is rolled into a U-shaped groove by rollers. At the same time, the uniformly mixed flux core is filled with a certain filling coefficient of 30-40%, and then rolled into an O-shape. After multiple drawing processes, it is made into a finished submerged arc wear-resistant flux-cored welding wire with a diameter of 2.4-4.0mm.

[0007] Preferably, the core contains the following components in parts by weight: 16-26 parts micro-carbon ferrochrome, 15-25 parts metallic chromium, 1-3 parts zircon sand, 7-11 parts cobalt powder, 14-18 parts nickel powder, 6-11 parts molybdenum powder, 2-3 parts rare earth ferrosilicon alloy, 2-5 parts ferroniobium, 5-7 parts low-carbon ferromanganese, 2-5 parts ferrovanadium, 1.5-3 parts ferrotitanium, 1-2 parts chromium nitride, and the balance being atomized iron powder, with a filling ratio of 38-39%.

[0008] Preferably, the core contains the following components in parts by weight: 26 parts micro-carbon ferrochrome, 15 parts metallic chromium, 1 part zircon sand, 7 parts cobalt powder, 18 parts nickel powder, 11 parts molybdenum powder, 2 parts rare earth ferrosilicon alloy, 3 parts niobium iron, 7 parts low-carbon ferromanganese, 5 parts vanadium iron, 2 parts titanium iron, 1 part chromium nitride, and 2 parts atomized iron powder, with a filling ratio of 38±0.5%.

[0009] Testing revealed that the weld wire provided by this invention has a Rockwell hardness of HRC 44-50 and an impact toughness of >75J. It exhibits strong wear resistance, crack resistance, and thermal fatigue resistance, significantly improving the service life of the mandrel, reducing downtime, lowering consumption, and increasing the operating rate of the rolling mill and the quality of the products.

[0010] The function of the alloy system powder core is as follows:

[0011] Chromium: An important component in martensite formation, it can improve the hardenability of weld metal and produce solid solution strengthening. The product of this invention uses N to replace C, and the microstructure of the weld metal is a very uniform and fine hexagonal Cr2N structure with a small amount of low-carbon martensitic carbides, which has good wear resistance. At the same time, chromium has the effect of promoting secondary hardening, forming a fine and dispersed precipitate phase, which can improve the hardness and tensile strength of the weld metal.

[0012] Molybdenum: It can improve the hardenability and hot strength of weld metal, refine grains, increase the red hardness of weld metal, prevent temper brittleness, and improve the strength and toughness of weld metal.

[0013] Nickel: Nickel is an austenite-forming element with high resistance to corrosion from acids and alkalis, and it exhibits rust prevention and heat resistance at high temperatures. It can prevent ferrite grains from coarsening and improve the low-temperature impact toughness of weld metal.

[0014] Vanadium: Vanadium is a strong ferrite-forming element and has a strong affinity for nitrogen (N), forming stable compounds that enhance resistance to hydrogen corrosion under high temperature and pressure. Trace amounts of vanadium can refine the grain structure, improving strength and toughness.

[0015] Cobalt: Cobalt is a rare and precious metal that can enhance the heat resistance of weld metal.

[0016] Rare earth ferrosilicon: can change the composition, morphology, distribution and properties of inclusions in weld metal, and improve the toughness and wear resistance of weld metal.

[0017] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0018] This specialized wear-resistant flux-cored welding wire is based on a Cr-Ni-Mo-Co-N alloy system, further refined with V-Ti-rare earth Si micro-alloying. The substitution of N for C not only inhibits ferrite formation and improves resistance to thermal fatigue, but also forms stable nitrides with chromium, molybdenum, cobalt, vanadium, and other elements in the alloy. These nitrides dispersed in the weld metal significantly enhance the high-temperature wear resistance, corrosion resistance, and high-temperature hardness of the welding material, resulting in a marked increase in the number of tubes that can be inserted. Detailed Implementation

[0019] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0020] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0021] Example 1

[0022] A high-temperature resistant submerged arc wear-resistant flux-cored welding wire for seamless mandrels, the flux core containing the following components in parts by weight: 26 parts micro-carbon ferrochrome, 15 parts metallic chromium, 1 part zircon sand, 7 parts cobalt powder, 18 parts nickel powder, 11 parts molybdenum powder, 2 parts rare earth ferrosilicon alloy, 3 parts niobium ferrometallurgical, 7 parts low-carbon ferromanganese, 5 parts ferrovanadium, 2 parts ferrotitanium, 1 part chromium nitride, and 2 parts atomized iron powder.

[0023] The preparation process is as follows: Low-carbon steel strip outer sheath, model HS1 (technical parameters are as follows: C: <0.04%, Mn: 0.1-0.45%, Si: <0.04%, S: <0.02%, P: <0.022%, yield strength: 140-180Mpa, tensile strength: 280-360Mpa), thickness 0.8mm, width 15mm, is used as the outer sheath of the welding wire. After degreasing and drying, it is rolled into a U-shaped groove by rollers. At the same time, the uniformly mixed flux core is filled with a filling coefficient of 30±0.5%, and then rolled into an O-shape. After multiple drawing processes, a finished submerged arc wear-resistant flux-cored welding wire with a diameter of 2.8mm is produced.

[0024] Example 2

[0025] A high-temperature resistant, wear-resistant flux-cored welding wire for seamless mandrels, the flux core comprising the following components in parts by weight: 22 parts micro-carbon ferrochrome, 18 parts metallic chromium, 1 part zircon sand, 8.6 parts cobalt powder, 18 parts nickel powder, 10 parts molybdenum powder, 2 parts rare earth ferrosilicon alloy, 2 parts niobium ferrometallurgical, 7 parts low-carbon ferromanganese, 3 parts vanadium ferrometallurgical, 1.5 parts ferrotitanium ferrometallurgical, 1.4 parts chromium nitride, and 5.5 parts atomized iron powder.

[0026] The preparation process is as follows: Low-carbon steel strip outer sheath, model HS1 (technical parameters are as follows: C: <0.04%, Mn: 0.1-0.45%, Si: <0.04%, S: <0.02%, P: <0.022%, yield strength: 140-180Mpa, tensile strength: 280-360Mpa), thickness 0.5mm, width 16mm, is used as the outer sheath of the welding wire. After degreasing and drying, it is rolled into a U-shaped groove by rollers. At the same time, the uniformly mixed flux core is filled with a filling coefficient of 38±0.5%, and then rolled into an O-shape. After multiple drawing passes, a finished submerged arc wear-resistant flux-cored welding wire with a diameter of 3.2mm is produced.

[0027] Example 3

[0028] A high-temperature resistant, wear-resistant flux-cored welding wire for seamless mandrels, the flux core comprising the following components in parts by weight: 20 parts micro-carbon ferrochrome, 20 parts metallic chromium, 2 parts zircon sand, 9 parts cobalt powder, 16 parts nickel powder, 9 parts molybdenum powder, 2.5 parts rare earth ferrosilicon alloy, 4 parts niobium ferrometallurgical, 5 parts low-carbon ferromanganese, 4 parts ferrovanadium, 3 parts ferrotitanium, 1.8 parts chromium nitride, and 3.7 parts atomized iron powder.

[0029] The preparation process is as follows: Low-carbon steel strip outer sheath, model HS1 (technical parameters are as follows: C: <0.04%, Mn: 0.1-0.45%, Si: <0.04%, S: <0.02%, P: <0.022%, yield strength: 140-180Mpa, tensile strength: 280-360Mpa), thickness 0.8mm, width 14mm, is used as the outer sheath of the welding wire. After degreasing and drying, it is rolled into a U-shaped groove by rollers. At the same time, the uniformly mixed flux core is filled with a filling coefficient of 40±0.5%, and then rolled into an O-shape. After multiple drawing passes, a finished submerged arc wear-resistant flux-cored welding wire with a diameter of 4.0mm is produced.

[0030] Example 4

[0031] A high-temperature resistant, wear-resistant flux-cored welding wire for seamless mandrels, the flux core comprising the following components in parts by weight: 22 parts micro-carbon ferrochrome, 22 parts metallic chromium, 3 parts zircon sand, 10 parts cobalt powder, 16 parts nickel powder, 6 parts molybdenum powder, 2.2 parts rare earth ferrosilicon alloy, 4 parts niobium ferrometallurgical, 5 parts low-carbon ferromanganese, 5 parts vanadium ferrometallurgical, 3 parts ferrotitanium ferrometallurgical, 1.8 parts chromium nitride, and 0 parts atomized iron powder.

[0032] The preparation process is as follows: Low-carbon steel strip outer sheath, model HS1 (technical parameters are as follows: C: <0.04%, Mn: 0.1-0.45%, Si: <0.04%, S: <0.02%, P: <0.022%, yield strength: 140-180Mpa, tensile strength: 280-360Mpa), thickness 0.6mm, width 15mm, is used as the outer sheath of the welding wire. After degreasing and drying, it is rolled into a U-shaped groove by rollers. At the same time, the uniformly mixed flux core is filled with a filling coefficient of 37±0.5%, and then rolled into an O-shape. After multiple drawing passes, a finished submerged arc wear-resistant flux-cored welding wire with a diameter of 3.2mm is produced.

[0033] Example 5

[0034] A high-temperature resistant submerged arc wear-resistant flux-cored welding wire for seamless mandrels, the flux core containing the following components in parts by weight: 16 parts micro-carbon ferrochrome, 24 parts metallic chromium, 2 parts zircon sand, 11 parts cobalt powder, 14 parts nickel powder, 8 parts molybdenum powder, 3 parts rare earth ferrosilicon alloy, 5 parts niobium ferrometallurgical, 6 parts low-carbon ferromanganese, 2 parts ferrovanadium, 2 parts ferrotitanium, 2 parts chromium nitride, and 5 parts atomized iron powder.

[0035] The preparation process is as follows: Low-carbon steel strip outer sheath, model HS1 (technical parameters are as follows: C: <0.04%, Mn: 0.1-0.45%, Si: <0.04%, S: <0.02%, P: <0.022%, yield strength: 140-180Mpa, tensile strength: 280-360Mpa), thickness 0.6mm, width 15mm, is used as the outer sheath of the welding wire. After degreasing and drying, it is rolled into a U-shaped groove by rollers. At the same time, the uniformly mixed flux core is filled with a filling coefficient of 33±0.5%, and then rolled into an O-shape. After multiple drawing passes, a finished submerged arc wear-resistant flux-cored welding wire with a diameter of 2.8mm is produced.

[0036] Example 6

[0037] A high-temperature resistant, wear-resistant flux-cored welding wire for seamless mandrels, the flux core comprising the following components in parts by weight: 16 parts micro-carbon ferrochrome, 25 parts metallic chromium, 3 parts zircon sand, 10 parts cobalt powder, 14 parts nickel powder, 8 parts molybdenum powder, 3 parts rare earth ferrosilicon alloy, 5 parts niobium ferroalloy, 6 parts low-carbon ferromanganese, 3 parts ferrovanadium, 2.5 parts ferrotitanium, 2 parts chromium nitride, and 2.5 parts atomized iron powder.

[0038] The preparation process is as follows: Low-carbon steel strip outer sheath, model HS1 (technical parameters are as follows: C: <0.04%, Mn: 0.1-0.45%, Si: <0.04%, S: <0.02%, P: <0.022%, yield strength: 140-180Mpa, tensile strength: 280-360Mpa), thickness 0.5mm, width 16mm, is used as the outer sheath of the welding wire. After degreasing and drying, it is rolled into a U-shaped groove by rollers. At the same time, the uniformly mixed flux core is filled with a filling coefficient of 30±0.5%, and then rolled into an O-shape. After multiple drawing processes, a finished submerged arc wear-resistant flux-cored welding wire with a diameter of 2.4mm is produced.

[0039] The properties of the deposited metal in each embodiment are shown in Table 1 below.

[0040] Table 1. Performance of deposited metal in each embodiment

[0041]

[0042] The hardness of the deposited metal is HRC: 44-50, and the impact toughness is >75J (the impact block is not notched).

[0043] The wear resistance test results for each embodiment are shown in Table 2 below.

[0044] Table 2. Wear resistance of welds in each embodiment

[0045]

[0046] Comparative Example 1

[0047] The difference between this comparative example and Example 1 is that the chromium nitride content in the core is 3% of the total core mass, while the remaining content and preparation process are the same as in Example 1. Testing revealed that increased chromium nitride content resulted in porosity at the weld joints.

[0048] Comparative Example 2

[0049] The difference between this comparative example and Example 1 is that the chromium nitride content in the flux core is 0.5% of the total flux core mass, while the remaining content and preparation process are the same as in Example 1. The wear resistance coefficient of the weld was tested to be 0.17.

[0050] Therefore, the chromium nitride content in this invention has a significant impact on the performance of the flux-cored welding wire. Excessive chromium nitride content will result in welding defects and porosity; insufficient chromium nitride content will lead to a reduction in the amount of nitride produced during welding and a decrease in the wear resistance of the material.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A high-temperature resistant, wear-resistant, flux-cored welding wire for seamless mandrels, comprising an outer sheath and a flux core, characterized in that... The core contains the following components in parts by weight: 26 parts micro-carbon ferrochrome, 15 parts metallic chromium, 1 part zircon sand, 7 parts cobalt powder, 18 parts nickel powder, 11 parts molybdenum powder, 2 parts rare earth ferrosilicon alloy, 3 parts niobium iron, 7 parts low-carbon ferromanganese, 5 parts vanadium iron, 2 parts titanium iron, 1 part chromium nitride, and 2 parts atomized iron powder, with a filling ratio of 38±0.5%.

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