CN114769939B - Welding wire for low-cost ultra-high strength steel laser welding - Google Patents
Welding wire for low-cost ultra-high strength steel laser welding Download PDFInfo
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- CN114769939B CN114769939B CN202210452335.1A CN202210452335A CN114769939B CN 114769939 B CN114769939 B CN 114769939B CN 202210452335 A CN202210452335 A CN 202210452335A CN 114769939 B CN114769939 B CN 114769939B
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- 238000003466 welding Methods 0.000 title claims abstract description 99
- 229910000797 Ultra-high-strength steel Inorganic materials 0.000 title claims abstract description 10
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 29
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 5
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 5
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 11
- 239000000203 mixture Substances 0.000 abstract description 4
- 229910000831 Steel Inorganic materials 0.000 description 41
- 239000010959 steel Substances 0.000 description 41
- 229910052751 metal Inorganic materials 0.000 description 15
- 239000002184 metal Substances 0.000 description 15
- 238000000034 method Methods 0.000 description 11
- 230000000171 quenching effect Effects 0.000 description 10
- 238000010791 quenching Methods 0.000 description 9
- 229910045601 alloy Inorganic materials 0.000 description 7
- 239000000956 alloy Substances 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 7
- 238000003856 thermoforming Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 229910001563 bainite Inorganic materials 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000003723 Smelting Methods 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- 238000005491 wire drawing Methods 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 238000005429 filling process Methods 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
- B23K35/3053—Fe as the principal constituent
- B23K35/3073—Fe as the principal constituent with Mn as next major constituent
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Laser Beam Processing (AREA)
Abstract
The invention belongs to the technical field of welding wires, and particularly relates to a low-cost welding wire for ultrahigh-strength steel laser welding. The composition comprises the following components in percentage by weight: c:0.15 to 0.20 percent; si:0.20 to 0.40 percent; mn:1.20 to 1.70 percent; cr:0.20 to 0.40 percent; mo:0.40 to 0.60 percent; p: less than or equal to 0.020%; s: less than or equal to 0.015 percent, and the balance of Fe and unavoidable impurity elements, wherein C+Cr/5+Mo/5 is more than or equal to 0.30. May also contain the following components: v:0% -0.15%, 0% -0.15% of Ti, and B:0.002 to 0.005 percent of Nb 0 to 0.15 percent. The joint strength of the hot-formed cold-rolled sheet after welding is more than 800MPa, after heating to 900-950 ℃ and preserving heat for 3-6 min, cooling at a speed of more than 50 ℃/s, more than 95% of the weld joint structure is converted into a martensitic structure, the strength of the welded joint is more than 1500MPa, and the production cost is lower.
Description
Technical Field
The invention belongs to the technical field of welding wires, and particularly relates to a low-cost welding wire for ultrahigh-strength steel laser welding.
Background
In order to meet the requirements of forming, strength, weight reduction and the like of parts on an automobile body, steel plates with the same thickness or different thicknesses are welded together in a laser welding mode. The hot forming steel laser tailor welded blank is a hot steel plate of the current laser tailor welded blank. The hot forming laser welding plate is formed by performing laser welding on two or more hot forming cold rolled plates, then placing the cold rolled plates into a heating furnace for heating to austenitizing, then rapidly placing the steel plates into a hot forming die for press forming, and quenching the steel plates in the die.
The steel plate has low strength and good formability at high temperature, and the steel plate structure becomes a martensitic structure after quenching, has high strength, is not easy to deform and has higher safety. After the laser splice welding plate is subjected to thermoforming and quenching, the structures of the steel plate and the welding seam are converted into martensite structures, but the welding joint becomes the weakest link because the steel plate at the joint of the laser welding has a certain burning loss. For laser splice welding plates with different plate thicknesses, the weld joint is not full and uniform, and the weld joint also becomes a weak link of the laser splice welding plate. The adoption of the laser filler wire welding process is an important means for improving the performance of the laser welding head.
At present, high-strength steel welding wires on the market are mainly designed for hot-rolled plate arc welding, the requirements of strength and low-temperature impact toughness of a steel plate need to be met, the welding wires are melted to form welding seams in arc discharge, and certain burning loss exists in welding wire components. In order to achieve higher toughness of a welding line when the welding line is designed, a martensitic structure of the welding line is avoided, the quenching property of the welding line is required to be controlled, the addition of alloy elements easy to quench is reduced, the noble metal element Ni is added, and the strength, toughness and plasticity of the welding line are improved through the Ni element. Therefore, the welding wire has high cost, high production cost for batch application and low cost performance. After being applied to the laser splice welding of the hot forming steel, the weld joint often cannot obtain a martensitic structure in the quenching process, so that the strength of the weld joint is low, and the laser splice welding production requirement of the hot forming steel cannot be met.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a welding wire for laser welding of low-cost ultrahigh-strength steel, which has the advantages that the joint strength is more than 800MPa after welding of a hot-forming cold-rolled sheet, the welding wire is heated to 900-950 ℃, the temperature is kept for 3-6 min, after cooling at a speed of more than 50 ℃/s, more than 95% of a welding seam structure is converted into a martensitic structure, the welding joint strength is more than 1500MPa, and the production cost is lower.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
the welding wire for the laser welding of the low-cost ultrahigh-strength steel comprises the following components in percentage by weight:
c:0.15 to 0.20 percent; si:0.20 to 0.40 percent; mn:1.20 to 1.70 percent; cr:0.20 to 0.40 percent; mo:0.40 to 0.60 percent; p: less than or equal to 0.020%; s: less than or equal to 0.015 percent, and the balance of Fe and unavoidable impurity elements, wherein C+Cr/5+Mo/5 is more than or equal to 0.30.
May also contain the following components:
V:0%~0.15%、Ti:0%~0.15%、B:0.002%~0.005%、Nb:0%~0.15%。
compared with the prior art, the method has the beneficial effects that:
the existing welding wire component system is designed to avoid the generation of martensitic structure of the welding seam, reduce the hardenability of weld metal, keep the welding seam to have better strength and have good impact toughness. The welding wire component system is designed to increase the hardenability of a welding seam, is easy to form a martensitic structure, keeps the high strength of the welding seam after quenching, and does not have specific requirements on the impact toughness of the welding seam.
(1) The alloy of the invention has low alloy content, especially no noble metal element Ni, and the welding wire has lower production cost.
(2) According to the welding wire component system, through alloy elements such as C, cr and Mo, the phase transition temperature of steel is increased in the continuous cooling process, the hardenability of weld metal is improved, the martensite formation temperature of the weld metal is improved, and a martensite structure is easy to obtain in the thermoforming process.
(3) According to the invention, the addition of Cr, mo, mn and other alloy elements is reduced by increasing the content of C, so that the production cost of the welding wire is effectively controlled. Meanwhile, the upper limit of the content of the high-carbon martensite is controlled, so that the high-carbon twin-crystal martensite structure is prevented from generating in weld metal, and particularly in the weld after thermoforming, the weld is easily cracked due to high defect density of the high-carbon twin-crystal martensite structure.
(4) According to the invention, the grains of the steel are refined by adding Mo element, so that the hardenability and the heat resistance of the steel plate are improved, the steel plate has higher strength and creep resistance at high temperature, and the effect of reducing the tempering brittleness of weld metal is achieved.
(5) The welding wire has easy quenching property, and solves the problem that weld metal of the welding joint of the prior hot forming steel cannot be quenched.
(6) The strength of the welded joint is more than or equal to 800MPa, and after heating to 900-950 ℃ and preserving heat for 3-6 min, the welded joint is cooled at a speed of more than 50 ℃/s, and the strength of the welded joint is more than or equal to 1500MPa.
Detailed Description
The invention discloses a welding wire for laser welding of low-cost ultrahigh-strength steel. Those skilled in the art can, with the benefit of this disclosure, suitably modify the process parameters to achieve this. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that variations and modifications can be made in the methods and applications described herein, and in the practice and application of the techniques of this invention, without departing from the spirit or scope of the invention.
The welding wire for the laser welding of the low-cost ultrahigh-strength steel comprises the following components in percentage by weight:
c:0.15 to 0.20 percent; si:0.20 to 0.40 percent; mn:1.20 to 1.70 percent; cr:0.20 to 0.40 percent; mo:0.40 to 0.60 percent; p: less than or equal to 0.020%; s: less than or equal to 0.015 percent, and the balance of Fe and unavoidable impurity elements, wherein C+Cr/5+Mo/5 is more than or equal to 0.30.
May also contain the following components:
V:0%~0.15%、Ti:0%~0.15%、B:0.002%~0.005%、Nb:0%~0.15%。
the invention has the following functions and purposes:
c is an important element for improving the strength of the welding seam and increasing the hardenability of the welding seam metal, the strength and the hardenability of the welding seam metal are obviously reduced when the content of C is low, and alloy elements such as Cr, mo, mn and the like are required to be added to improve the strength and the hardenability of the welding seam metal, so that the production cost is improved. When the C content is high, the hardness and strength of the welding wire are greatly improved, carbide and cementite are easy to generate in steel, the wire is easy to break in the drawing process of the welding wire, and the production continuity is affected. Meanwhile, when the C content is high, a high-carbon martensitic structure is easy to generate in weld metal, particularly in a weld after thermoforming, a twin-crystal martensitic structure appears in the weld, and the dislocation density is high, so that the weld is easy to crack. Comprehensively considering that the mass percentage of the C element is designed to be 0.15-0.20%.
Si is a deoxidizing element and also has a solid solution strengthening effect in the weld metal. The Si content in the welding wire is low, the deoxidization is insufficient, and the increase of the oxide of the welding wire affects the drawing and the strength of the welding wire. An excessively high Si content increases nonmetallic inclusions in the weld bead and slag on the surface of the weld bead. Comprehensively considering that the Si content of the welding wire is controlled between 0.20 percent and 0.40 percent.
Mn element can not only improve the strength of the welding seam, but also play a role in deoxidization. Mn is an austenite stabilizing element, and as the Mn content increases, the strength of the steel sheet increases, but the Mn content is too high, and segregation is likely to be formed during continuous casting of molten steel. Comprehensively considering that the Mn content in the welding wire is controlled between 1.20 percent and 1.70 percent.
P, S is a harmful element, the lower the content in the welding wire is, the better, but the smelting cost of deep P and S removal is higher, and the welding wire P of the invention is comprehensively considered: less than or equal to 0.020%; s: less than or equal to 0.015 percent.
Cr can increase the hardenability of steel, can improve the hardness and strength of weld metal, and the elongation and the reduction of area of the welding wire are reduced along with the increase of Cr content, which is unfavorable for the drawing production of the welding wire. However, with the increase of Cr content, the combined action of the Cr and C, mo elements improves the hardenability of the weld metal, which is beneficial to obtaining a martensitic structure in the thermoforming process. Comprehensively considering that the content of Cr is controlled to be 0.20% -0.40%.
Mo is an important element capable of reducing the austenite phase region of steel and improving the hardenability and heat resistance of the steel plate. Can have higher strength and creep resistance at high temperature, and has the function of reducing tempering brittleness. Excessive addition causes large quenching capacity of weld metal, a twin crystal substructure is easy to form in the weld, and the microstructure is easy to form microcracks, so that weld quality defects are caused. The content of Mo in the welding wire is 0.40-0.60%.
Nb, V and Ti all have refined grains in the welding wire, so that the strength is improved without reducing the toughness of the welding seam. Can form a precipitated phase with C, N in steel, inhibit the growth of austenite grains, reduce failure sensitivity and cold brittleness, and improve welding performance. The large amount of precipitated phases directly influence the drawing performance of the welding wire, and lead to the drawing breakage of the welding wire. Therefore, it needs to be added appropriately.
B is an element for strongly improving the hardenability of steel, and trace B can obviously improve the hardenability of the steel plate. B has strong affinity with O, N and is easy to generate nonmetallic inclusion.
The welding wire is manufactured through the procedures of molten steel smelting, casting, wire rod rolling, welding wire drawing and the like.
[ example ]
Molten steel was smelted using a 200kg vacuum furnace, and cast into steel ingots with chemical compositions shown in table 1. The steel ingot is rolled into a wire rod with the diameter of 5.5mm, and the wire rod is subjected to procedures of pickling, cleaning, drying, wire drawing, copper plating and the like to prepare a finished welding wire with the diameter of 1.2mm.
And (3) carrying out laser filler wire welding on the welding wire on laser welding equipment, heating the welded steel plate in a heating furnace at 890-950 ℃ for 3-7 min, and then rapidly putting the steel plate in a thermoforming die for stamping and quenching.
Table 1 chemical composition of steel ingot and chemical composition (wt%) of comparative example
The same laser wire filling process is adopted to weld a 1500 MPa-level 22MnB5 hot-formed steel plate, the steel plate is placed into a heating furnace to be heated after welding, the heating temperature is 950 ℃, the heat is preserved for 5 minutes, the steel plate is taken out and placed into a hot-formed die to be subjected to stamping forming and quenching, and the mechanical property and weld structure of the quenched steel plate are detected, so that the results are shown in Table 2. The weld of the mechanical test specimen is at the center of the specimen and perpendicular to the tensile specimen.
TABLE 2 mechanical Properties of laser tailor welded blanks
Tensile strength MPa | Tissue of | |
Example 1 | 1514 | Martensitic phase |
Example 2 | 1520 | Martensitic phase |
Example 3 | 1545 | Martensitic phase |
Example 4 | 1535 | Martensitic phase |
Example 5 | 1550 | Martensitic phase |
Example 6 | 1540 | Martensitic phase |
Example 7 | 1538 | Martensitic phase |
Comparative example 1 | 1145 | Martensite+bainite |
Comparative example 2 | 1180 | Martensite+bainite |
Comparative example 3 | 1150 | Martensite+bainite |
Comparative example 4 | 1025 | Martensite+bainite |
The invention is a welding wire suitable for 1500 MPa-level hot forming steel laser welding, and the joint strength after welding is more than or equal to 800MPa. After heating at 900-950 ℃ and preserving heat for 3-6 min, cooling at a speed of more than 50 ℃/s, converting more than 95% of weld joint structure into martensitic structure, and the strength of the welded joint is more than 1500MPa, thereby having lower production cost.
Compared with the existing high-strength steel welding wire with the same grade, the welding wire has low alloy content, particularly has no noble metal element Ni, and has lower production cost. The invention has the hardenability at the same time, and solves the problem that the weld metal of the welding joint of the prior hot forming steel cannot be quenched.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (2)
1. The welding wire for laser welding of the low-cost ultrahigh-strength steel is characterized by comprising the following components in percentage by weight:
c:0.15 to 0.20 percent; si:0.20 to 0.40 percent; mn:1.20 to 1.70 percent; cr:0.20 to 0.40 percent; mo:0.40 to 0.60 percent; p: less than or equal to 0.020%; s: less than or equal to 0.015 percent, and the balance of Fe and unavoidable impurity elements, wherein C+Cr/5+Mo/5 is more than or equal to 0.30;
realizing the joint strength of more than 800MPa after the hot forming cold-rolled sheet is welded, and after heating to 900-950 ℃ and preserving heat for 3-6 min, cooling at a speed of more than 50 ℃/s, converting more than 95% of weld joint structure into martensitic structure, and the welding joint strength is more than 1500MPa.
2. The welding wire for laser welding of low-cost ultra-high strength steel according to claim 1, further comprising the following components in weight percent:
V:0%~0.15%、Ti:0%~0.15%、B:0.002%~0.005%、Nb:0%~0.15%。
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Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5947071A (en) * | 1982-08-02 | 1984-03-16 | Kobe Steel Ltd | Latent arc welding method of cr-mo low alloy steel |
US4561888A (en) * | 1982-11-02 | 1985-12-31 | Kabushiki Kaisha Kobe Seiko Sho | Welding wire for use in submerged arc welding of Cr-Mo steels |
JPS6310096A (en) * | 1986-07-01 | 1988-01-16 | Nippon Steel Corp | Tig welding wire for cr-mo steel |
JP2003285196A (en) * | 2002-03-27 | 2003-10-07 | Kobe Steel Ltd | Solid wire for gas-shield arc welding and its raw wire |
CN101906594A (en) * | 2009-06-08 | 2010-12-08 | 鞍钢股份有限公司 | 900 MPa-grade yield strength quenched and tempered steel plate and manufacturing method thereof |
CN106350741A (en) * | 2016-10-24 | 2017-01-25 | 大连理工大学 | Laser tailor-welded high-strength steel warm forming preparation method |
CN108778612A (en) * | 2016-03-09 | 2018-11-09 | 萨尔茨吉特法特尔有限公司 | High intensity air-hardening steel as welding added material |
-
2022
- 2022-04-27 CN CN202210452335.1A patent/CN114769939B/en active Active
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5947071A (en) * | 1982-08-02 | 1984-03-16 | Kobe Steel Ltd | Latent arc welding method of cr-mo low alloy steel |
US4561888A (en) * | 1982-11-02 | 1985-12-31 | Kabushiki Kaisha Kobe Seiko Sho | Welding wire for use in submerged arc welding of Cr-Mo steels |
JPS6310096A (en) * | 1986-07-01 | 1988-01-16 | Nippon Steel Corp | Tig welding wire for cr-mo steel |
JP2003285196A (en) * | 2002-03-27 | 2003-10-07 | Kobe Steel Ltd | Solid wire for gas-shield arc welding and its raw wire |
CN101906594A (en) * | 2009-06-08 | 2010-12-08 | 鞍钢股份有限公司 | 900 MPa-grade yield strength quenched and tempered steel plate and manufacturing method thereof |
CN108778612A (en) * | 2016-03-09 | 2018-11-09 | 萨尔茨吉特法特尔有限公司 | High intensity air-hardening steel as welding added material |
CN106350741A (en) * | 2016-10-24 | 2017-01-25 | 大连理工大学 | Laser tailor-welded high-strength steel warm forming preparation method |
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