1200MPa-grade high-strength and high-toughness gas shielded welding wire as well as preparation method and application thereof

Abstract

The invention relates to the technical field of welding wires, in particular to a 1200 MPa-grade high-strength and high-toughness gas shielded welding wire as well as a preparation method and application thereof. The 1200 MPa-grade high-strength and high-toughness gas shielded welding wire comprises the following components in percentage by mass: 0.06%-0.12% of C, 0.2%-0.6% of Si, 1.6%-2.5% of Mn, less than or equal to 0.005% of S, less than or equal to 0.008% of P, 0.3%-0.8% of Cr, 2.5%-4.5% of Ni, 0.6%-1.2% of Mo, 0.03%-0.15% of Ti, 0.02%-0.05% of Al, 0.004%-0.012% of B, 0.02%-0.04% of Zr, 0.02%-0.05% of Re and the balance of Fe and impurities. Re comprises Y and Ce; (Omega Zr + Omega Re) / Omega B < = 10. The low-temperature toughness of weld metal can be improved, and the crack resistance is excellent.

Description

Technical Field

[0001] The present invention relates to the technical field of welding wires, and more particularly, to a 1200 MPa grade high-strength and high-toughness gas shielded welding wire, its preparation method and application. Background Art

[0002] High-strength steels are widely used in many fields such as automobiles, buildings, bridges, and ships due to their excellent strength and toughness and good weldability. Using higher-strength steels in the construction process can increase the structural stability, reduce the material consumption, and improve the engineering efficiency.

[0003] With the increasing optimization of the steel production process, the strength level of steels has been continuously improved, and currently, high-strength steels with a strength level of 1200 MPa can be mass-produced. However, during the welding construction of 1200 MPa grade high-strength steels, the low-temperature toughness of the welded joints prepared by the currently disclosed welding materials can only reach 27 J, and there is also a problem of high crack sensitivity of the joints. The strength and toughness of the welded joints do not match those of the base metal, which affects the application of this important material in fields such as offshore engineering and oil and gas transportation.

[0004] Therefore, it is of great significance to develop a 1200 MPa grade welding material to meet the actual engineering application needs.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The first object of the present invention is to provide a 1200 MPa grade high-strength and high-toughness gas shielded welding wire. By introducing B, Zr, and Re, and satisfying that the sum of the mass percentages of Zr and Re / the mass percentage of B ≤ 10, the morphology of the precipitates at the microvoid aggregation fracture dimples can be improved, and the low-temperature toughness of the weld metal can be increased; using the welding wire with this specific composition, there are no defects such as spatter and pores during the welding process, the weld metal has a beautiful shape, no cracks in the side bend test, and excellent crack resistance. It solves the problems of low low-temperature toughness of the welded joints prepared by welding materials and high crack sensitivity of the joints.

[0007] The second object of the present invention is to provide a preparation method for a 1200 MPa grade high-strength and high-toughness gas shielded welding wire. The roller die drawing process can be used to reduce the internal stress of the welding wire, improve the wire feeding stability, and optimize the weld forming quality.

[0008] The third object of the present invention is to provide the application of a 1200 MPa grade high-strength and high-toughness gas shielded welding wire in welding steel.

[0009] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0010] The present invention first provides a 1200MPa grade high-strength and high-toughness gas shielded welding wire, which comprises the following components by mass percentage: C 0.06% - 0.12%, Si 0.2% - 0.6%, Mn 1.6% - 2.5%, S ≤ 0.005%, P ≤ 0.008%, Cr 0.3% - 0.8%, Ni 2.5% - 4.5%, Mo 0.6% - 1.2%, Ti 0.03% - 0.15%, Al 0.02% - 0.05%, B 0.004% - 0.012%, Zr 0.02% - 0.04%, Re 0.02% - 0.05%, and the balance is Fe and inevitable impurities; wherein, the Re includes Y and Ce; the mass percentage sum of the Zr and the Re / the mass percentage of the B ≤ 10.

[0011] Further, the 1200MPa grade high-strength and high-toughness gas shielded welding wire comprises the following components by mass percentage: C 0.08% - 0.10%, Si 0.20% - 0.45%, Mn 1.8% - 2.2%, S ≤ 0.005%, P ≤ 0.008%, Cr 0.5% - 0.7%, Ni 3.2% - 4.2%, Mo 0.8% - 1.2%, Ti 0.05% - 0.10%, Al 0.02% - 0.04%, B 0.004% - 0.012%, Zr 0.02% - 0.04%, Re 0.02% - 0.04%, and the balance is Fe and inevitable impurities.

[0012] Further, the mass percentage sum of the Zr and the Re / the mass percentage of the B is 5 - 10.

[0013] Further, the mass ratio of the Y and the Ce is 25:75.

[0014] The present invention further provides a preparation method of the above-mentioned 1200MPa grade high-strength and high-toughness gas shielded welding wire, which comprises the following steps: vacuum induction smelting each raw material, then electroslag remelting and refining, and then continuous casting billet hot rolling to obtain wire rods; after the wire rods are polished and short-time annealed, roller die drawing is carried out to obtain the 1200MPa grade high-strength and high-toughness gas shielded welding wire.

[0015] Further, the temperature of the short-time annealing is 750 - 800°C, and the heat preservation time is 0.5 - 1.5h.

[0016] Further, the diameter of the wire rod is 5.5 mm, and the wire drawing is carried out in 9 passes. The wire drawing speed in the first pass is 0.8 - 1.2 m / min, the wire drawing speed in the first four passes increases gradually by 13% - 17% pass by pass, the wire drawing speed in the last five passes is the same as that in the fourth pass, and the last pass is eye die drawing to produce the 1200 MPa grade high-strength and high-toughness gas shielded welding wire with a diameter of 1.2 mm.

[0017] The present invention also provides the process parameters of the above 1200 MPa grade high-strength and high-toughness gas shielded welding wire during the steel welding process.

[0018] Further, the welding current is 220 - 280 A, the welding voltage is 24 - 30 V, the welding speed is 350 - 400 mm / min, the flow rate of the shielding gas used in the welding is 18 - 22 L / min, the preheating temperature of the base metal for welding is ≥100 °C, the interlayer temperature of the welding is 120 - 150 °C, and post-weld heat treatment is carried out at 270 - 320 °C.

[0019] Further, the shielding gas includes argon and carbon dioxide with a volume ratio of 85 - 90:10 - 15.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) By introducing B, Zr, and Re and controlling the mass ratio of Zr + Re to B, the present invention can improve the morphology and quantity of precipitates in the low-temperature impact fracture dimples, increase the absorption energy of the weld metal for ductile fracture caused by microvoid coalescence under impact load, and thus improve the low-temperature toughness of the weld metal.

[0022] (2) By regulating the contents of Si, Mn, Cr, Ni, and Mo in the main alloy components of the welding wire, the present invention reduces the temperature of austenite to ferrite transformation, decreases the quantity of proeutectoid ferrite, and adds compounds formed by Ti and Al elements as heterogeneous nucleation sites, enabling more austenite to transform into acicular ferrite and improving the strength and toughness of the weld metal.

[0023] (3) The present invention adopts the roller die drawing process, which can reduce the internal stress of the welding wire, improve the wire feeding stability, and optimize the weld forming quality.

[0024] (4) The present invention adopts a mixed shielding gas of Ar and CO2 with a specific ratio, and has excellent welding processability, and there are no defects such as pores and inclusions in the weld metal. Description of the Drawings

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings required for the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0026] Figure 1 It is the side bend test result of the welded joint obtained after TIG welding with the 1200 MPa grade high-strength and high-toughness gas shielded welding wire of Example 1.

[0027] Figure 2 It is the side bend test result of the welded joint obtained after TIG welding with the welding wire of Comparative Example 7. Specific Embodiments

[0028] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For those reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0029] If there is no special description, in the present invention, "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "the first", "the second", "the third", "the fourth", etc. only serve for non-exhaustive list description purposes and should be understood not to constitute a closed limitation on the quantity.

[0030] If there is no special description, "including" and "comprising" mentioned in the present invention mean open-ended, and can also be closed-ended. For example, "including" and "comprising" can mean that other components not listed can also be included, or only the listed components can be included.

[0031] If there is no special description, in the present invention, "one or more" or "at least one" refers to any one, any two or any two or more of the listed items. Among them, "several" refers to any two or any two or more.

[0032] In a first aspect, the present invention provides a 1200 MPa grade high-strength and high-toughness gas shielded welding wire, which comprises the following components by mass percentage: C 0.06% to 0.12%, Si 0.2% to 0.6%, Mn 1.6% to 2.5%, S ≤ 0.005%, P ≤ 0.008%, Cr 0.3% to 0.8%, Ni 2.5% to 4.5%, Mo 0.6% to 1.2%, Ti 0.03% to 0.15%, Al 0.02% to 0.05%, B 0.004% to 0.012%, Zr 0.02% to 0.04%, Re 0.02% to 0.05%, and the balance is Fe and unavoidable impurities.

[0033] Among them, C includes, by mass percentage, but is not limited to, the point value of any one of 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12% or the range value between any two of them; Si includes, by mass percentage, but is not limited to, the point value of any one of 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6% or the range value between any two of them; Mn includes, by mass percentage, but is not limited to, the point value of any one of 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5% or the range value between any two of them; S includes, by mass percentage, but is not limited to, the point value of any one of 0.005%, 0.0045%, 0.004%, 0.003% or the range value between any two of them; P includes, by mass percentage, but is not limited to, the point value of any one of 0.008%, 0.007%, 0.006%, 0.005% or the range value between any two of them; C includes, by mass percentage, but is not limited to, the point value of any one of 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% or the range value between any two of them; Ni includes, by mass percentage, but is not limited to, the point value of any one of 2.5%, 3.0%, 3.5%, 4.0%, 4.5% or the range value between any two of them; Mo includes, by mass percentage, but is not limited to, the point value of any one of 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2% or the range value between any two of them; Ti includes, by mass percentage, but is not limited to, the point value of any one of 0.03%, 0.05%, 0.06%, 0.08%, 0.1%, 0.12%, 0.13%, 0.15% or the range value between any two of them; Al includes, by mass percentage, but is not limited to, the point value of any one of 0.02%, 0.03%, 0.04%, 0.05% or the range value between any two of them; B includes, by mass percentage, but is not limited to, the point value of any one of 0.004%, 0.005%, 0.008%, 0.01%, 0.012% or the range value between any two of them; Zr includes, by mass percentage, but is not limited to, the point value of any one of 0.02%, 0.025%, 0.03%, 0.035%, 0.04% or the range value between any two of them; Re includes, by mass percentage, but is not limited to, the point value of any one of 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045, 0.05% or the range value between any two of them.

[0034] Among them, Re is a rare earth element, and the Re includes Y and Ce.

[0035] The sum of the mass percentages of Zr and Re / the mass percentage of B ≤ 10, such as 10, 9, 8, 7, 6 or 5. That is, the ratio of the sum of the mass percentages of Zr and Re to the mass percentage of B ≤ 10, abbreviated as (ω Zr + ω Re ) / ω B .

[0036] And the sum of the mass percentages of Zr and Re / the mass percentage of B > 0.

[0037] By introducing B, Zr and Re and controlling the mass ratio of Zr + Re to B, the present invention can improve the morphology and quantity of precipitates in the low-temperature impact fracture dimples, increase the absorbed energy of the weld metal during ductile fracture caused by microvoid coalescence under impact load, and thus improve the low-temperature toughness of the weld metal.

[0038] Meanwhile, by regulating the contents of Si, Mn, Cr, Ni, and Mo in the main alloy components of the welding wire, the present invention reduces the temperature of austenite-to-ferrite transformation, decreases the quantity of proeutectoid ferrite, and adds compounds formed by Ti and Al elements as heterogeneous nucleation sites, enabling more austenite to transform into acicular ferrite and improving the strength and toughness of the weld metal.

[0039] The 1200 MPa grade high-strength and high-toughness gas shielded welding wire provided by the present invention has a specific chemical composition. When welding with this welding wire, there are no defects such as spatter and pores during the welding process, the weld metal has a beautiful shape, there are no cracks in the side bend test, and the crack resistance is excellent. The performance of the welding consumables meets the actual engineering application requirements of 1200 MPa grade high-strength steel.

[0040] In the present invention, the functions of each component in the 1200 MPa grade high-strength and high-toughness gas shielded welding wire are as follows:

[0041] C 0.06% - 0.12%: In the weld metal, the C element improves the strength and hardness of the weld metal through solid solution strengthening and the second-phase strengthening effect of forming carbides; however, C increases the hardenability of the weld metal, increases the martensite content in the solidification structure, reduces the low-temperature toughness of the weld metal, and increases the crack sensitivity of the weld metal. Therefore, the C content is controlled at 0.06% - 0.12% in the present invention.

[0042] Si 0.2% - 0.6%: In the weld metal, the Si element has functions such as deoxidation, reducing pores and inclusions in the weld metal; Si can improve the fluidity of the weld metal and the forming quality of the weld metal; Si can improve the strength of the weld metal through solid solution strengthening; however, excessive Si will segregate at the grain boundaries, generate brittle phases, and reduce the low-temperature toughness of the weld metal; too high Si content will also reduce the arc stability. Therefore, the Si content is controlled at 0.2% - 0.6% in the present invention.

[0043] Mn 1.6% - 2.5%: Mn dissolves in austenite, which has the effect of solid solution strengthening to improve the strength of the weld metal; Mn has a stabilizing effect on austenite, increasing the retained austenite content in the weld metal and improving the low-temperature toughness of the weld metal; however, excessive Mn will cause the coarsening of the weld metal structure and increase the cold crack tendency of the weld metal. In the present invention, the Mn content is controlled within 1.6% - 2.5%.

[0044] S ≤ 0.005%, P ≤ 0.008%: The low-melting eutectic of S in the weld metal is the main cause of inducing liquation cracks; P segregates at grain boundaries, resulting in temper embrittlement during multi-layer and multi-pass welding of the weld metal and reducing the mechanical properties of the weld metal. Considering the smelting level and economic benefits, in the present invention, S ≤ 0.005% and P ≤ 0.008%.

[0045] Cr 0.3% - 0.8%: The Cr element improves the strength in the weld metal through solid solution strengthening and precipitation strengthening. The carbon-chromium compound has a pinning effect on grain boundaries, which is beneficial to grain refinement. The carbon-chromium compound serves as a nucleation site to promote the nucleation of acicular ferrite. However, excessive Cr will promote the formation of hard and brittle coarse M / A constituents. Therefore, in the present invention, the Cr content is controlled within 0.3% - 0.8%.

[0046] Ni 2.5% - 4.5%: Ni and Fe can be infinitely miscible in the weld metal, expanding the austenite phase region, reducing the transformation temperature from austenite to ferrite. More ferrite precipitates as acicular ferrite, and at the same time, more retained austenite remains in the weld metal, improving the strength and toughness. However, high Ni will cause abnormal growth of the ferrite structure. Therefore, in the present invention, the Ni content is controlled within 2.5% - 4.5%.

[0047] Mo 0.6% - 1.2%: Mo has a strong binding force with C, forming fine carbides that have a precipitation strengthening effect on the weld metal; Mo can reduce the driving force for the transformation from austenite to ferrite and expand the intermediate-temperature transformation range; an appropriate amount of Mo can increase the acicular ferrite content in the weld metal, but excessive Mo in the weld metal will promote the formation of martensite structure. Therefore, in the present invention, the Mo content is controlled within 0.6% - 1.2%.

[0048] Ti 0.03% - 0.15%: Ti has a strong binding force with O. Adding a certain amount of Ti to the weld metal can, on the one hand, play a role in deoxidation, and on the other hand, the formed oxides serve as nucleation sites to promote the formation of acicular ferrite, improving the strength and toughness of the weld metal; too much Ti content will segregate at grain boundaries, affecting the toughness of the weld metal, and a higher Ti content in the wire composition will reduce the welding processability. Therefore, in the present invention, the Ti content is controlled within 0.03% - 0.15%.

[0049] Al 0.02% - 0.05%: The oxides formed by Al in the weld metal have a good promoting effect on acicular ferrite. However, if the Al content is too high, coarse inclusions will be formed, which will become the crack source under low-temperature impact load and reduce the toughness of the weld metal. Therefore, in the present invention, the Al content is controlled at 0.02% - 0.05%.

[0050] B 0.004% - 0.012%: In the present invention, a certain amount of B is added to the weld metal to form uniform and fine precipitates with Zr and rare earth elements, improving the morphology and quantity of the precipitates in the low-temperature impact fracture dimples, increasing the absorption energy of microvoid coalescence-induced ductile fracture under impact load in the weld metal, and thus enhancing the low-temperature toughness of the weld metal. Therefore, in the present invention, the B content is controlled at 0.004% - 0.012%.

[0051] Zr 0.02% - 0.04%: In the present invention, a certain amount of Zr is added to the weld metal to form fine precipitates that pin the austenite grain boundaries, refine the ferrite structure transformed from austenite, and at the same time, the fine precipitates increase the impact fracture resistance of the weld metal, improving the strength and toughness of the weld metal. If the Zr content is too high, it will promote the formation of coarse precipitates. Therefore, in the present invention, the Zr content is controlled at 0.02% - 0.04%.

[0052] Re 0.02% - 0.05%: In the present invention, iridium and cerium are added to the weld metal to optimize the morphology and quantity of the precipitates in the weld metal, improve the morphology and quantity of the precipitates in the low-temperature impact fracture dimples, promote the nucleation of acicular ferrite, and enhance the strength and toughness of the weld metal. Therefore, in the present invention, the Re content is controlled at 0.02% - 0.05%.

[0053] During the welding process, B is oxidized and burned. When the mass difference between (Zr + Re) and B is large, and when Zr and rare earth elements are in excess, they are likely to react with O and N in the molten pool to form coarse oxides and nitrides. To promote the reaction of B with Zr and rare earth elements to form fine compounds and reduce the content of coarse oxides and nitrides, in the present invention, the mass ratio of (Zr + Re) to B is controlled ≤ 10.

[0054] In some specific embodiments, to further improve the low-temperature toughness of the weld metal, the 1200 MPa grade high-strength and high-toughness gas shielded welding wire comprises the following components by mass percentage: C 0.08% - 0.10%, Si 0.20% - 0.45%, Mn 1.8% - 2.2%, S ≤ 0.005%, P ≤ 0.008%, Cr 0.5% - 0.7%, Ni 3.2% - 4.2%, Mo 0.8% - 1.2%, Ti 0.05% - 0.10%, Al 0.02% - 0.04%, B 0.004% - 0.012%, Zr 0.02% - 0.04%, Re 0.02% - 0.04%, and the balance is Fe and unavoidable impurities. Wherein, (the sum of the mass percentages of Zr and Re) / (the mass percentage of B) ≤ 10.

[0055] In some specific embodiments, (the sum of the mass percentages of Zr and Re) / (the mass percentage of B) is 5 - 10, such as 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9 or 9.5.

[0056] In some specific embodiments, the mass ratio of Y and Ce is 25:75.

[0057] In some specific embodiments, the tensile strength of the weld metal obtained after welding with the 1200 MPa grade high-strength and high-toughness gas shielded welding wire is ≥ 1200 MPa, the yield strength is ≥ 1050 MPa, and the impact absorption energy in the -40 °C Charpy pendulum test is ≥ 47 J.

[0058] In the second aspect, the present invention provides a preparation method of the above-mentioned 1200 MPa grade high-strength and high-toughness gas shielded welding wire, comprising the following steps: subjecting each raw material to vacuum induction melting, then performing electroslag remelting refining, and then hot rolling the cast billet to obtain wire rods.

[0059] Among them, electroslag remelting refining is a method of melting and removing impurities from steel by heating the refining slag with an electric current.

[0060] Hot rolling of the cast billet is a process of heating the cast billet to a certain temperature and then deforming it into wire by mechanical pressure.

[0061] After the wire rods are polished and subjected to short-time annealing, they are subjected to roller die drawing to obtain the 1200 MPa grade high-strength and high-toughness gas shielded welding wire.

[0062] Aiming at the problems that the 1200 MPa grade high-strength steel gas shielded welding wire has a high hardness and a high stress after drawing, which affects the wire feeding performance during welding, the present invention adopts the roller die drawing process. By roller die drawing, the internal stress of the welding wire is reduced, the wire feeding stability can be improved, and the weld forming quality can be optimized.

[0063] It can be understood that each raw material is weighed according to the target composition.

[0064] In some specific embodiments, the temperature of the short-time annealing is 750 - 800 °C, such as 760 °C, 770 °C, 780 °C or 790 °C. The holding time of the short-time annealing is 0.5 - 1.5 h, such as 1 h.

[0065] In some specific embodiments, the wire drawing is carried out in 9 passes. The wire drawing speed of the first pass is 0.8 - 1.2 m / min, such as 1 m / min; the wire drawing speeds of the first four passes increase by 13% - 17% successively, such as 15%; the wire drawing speeds of the last five passes are the same as that of the fourth pass, and the last pass is eye die wire drawing. Among them, eye die wire drawing refers to the process of wire drawing by shearing the diameter through a hard die with different hole diameters at both ends of the wire.

[0066] Adopting the above-mentioned roller die wire drawing process can improve the wire drawing efficiency, reduce the internal stress of the wire, and improve the wire feeding stability.

[0067] In some specific embodiments, the diameter of the wire rod is Ф5.5 mm.

[0068] In some specific embodiments, a 1200 MPa grade high-strength and high-toughness gas shielded welding wire with a diameter of Ф1.2 mm is prepared.

[0069] In some specific embodiments, after the wire drawing, a step of ultrasonic cleaning is further included.

[0070] In the third aspect, the present invention provides the application of the above-mentioned 1200 MPa grade high-strength and high-toughness gas shielded welding wire in welding steel.

[0071] The 1200 MPa grade high-strength and high-toughness gas shielded welding wire provided by the present invention can be used for TIG welding of 1200 MPa grade high-strength steel. The strength and toughness of the welded joint are matched with those of the base metal, which is beneficial to expanding the application of 1200 MPa grade high-strength steel in the fields of offshore engineering, oil and gas transportation, etc.

[0072] In some specific embodiments, the current of the welding is 220 - 280 A, including but not limited to any point value of 220 A, 230 A, 240 A, 250 A, 260 A, 270 A, 280 A or the range value between any two of them.

[0073] The voltage of the welding is 24 - 30 V, including but not limited to any point value of 24 V, 25 V, 26 V, 27 V, 28 V, 29 V, 30 V or the range value between any two of them.

[0074] The welding speed is 350 - 400 mm / min, including but not limited to any point value among 350 mm / min, 360 mm / min, 370 mm / min, 380 mm / min, 390 mm / min, 400 mm / min or the range value between any two of them.

[0075] The flow rate of the shielding gas used for the welding is 18 - 22 L / min, including but not limited to any point value among 18 L / min, 19 L / min, 20 L / min, 21 L / min, 22 L / min or the range value between any two of them.

[0076] The preheating temperature of the base metal for the welding is ≥100 °C, including but not limited to any point value among 110 °C, 120 °C, 130 °C, 140 °C, 150 °C or the range value between any two of them. That is, the base metal is preheated to above 100 °C before welding.

[0077] The interpass temperature of the welding (i.e., the temperature between two welding passes) is 120 - 150 °C, including but not limited to any point value among 120 °C, 130 °C, 140 °C, 150 °C or the range value between any two of them.

[0078] After the welding, post - heat treatment is carried out at 270 - 320 °C, such as 300 °C. Among them, post - heat treatment can remove hydrogen. Removing hydrogen can reduce crack sensitivity and improve tensile properties.

[0079] In some specific embodiments, the shielding gas includes argon and carbon dioxide with a volume ratio of 85 - 90:10 - 15.

[0080] By regulating the composition and proportion of the welding shielding gas, the present invention has excellent welding processability, and there are no defects such as pores and inclusions in the weld metal, optimizing the welding processability.

[0081] The measurement of the wire composition shows that the use of a mixed shielding gas with a specific ratio of Ar and CO2 reduces the C loss in the weld metal. The observation of the microstructure finds that the use of a mixed shielding gas with a specific ratio of Ar and CO2 improves the morphology of the precipitates in the weld metal.

[0082] Hereinafter, the embodiments of the present invention will be described in detail in conjunction with the examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0083] Examples 1 - 5

[0084] The chemical compositions of the 1200 MPa grade high-strength and high-toughness gas shielded welding wires provided in Examples 1 to 5 are shown in Table 1 respectively.

[0085] The preparation method of the 1200 MPa grade high-strength and high-toughness gas shielded welding wires provided in Examples 1 to 5 is as follows:

[0086] (1) According to the target composition, mix the raw materials evenly and then successively carry out vacuum induction melting, electroslag remelting refining, and continuous casting billet hot rolling to obtain a wire rod with a diameter of Ф5.5 mm.

[0087] (2) After the wire rod is polished and annealed at 780 °C for 1 h, it is connected to a roller die drawing machine for roller die drawing. A total of 9 passes of drawing are carried out. The drawing speed of the first pass is 1 m / min, the drawing speed of the first four passes increases by 15% successively, the drawing speed of the last five passes is the same as that of the fourth pass, and the last pass is eye die drawing. Then, ultrasonic cleaning is carried out to obtain a finished welding wire with a diameter of Ф1.2 mm, that is, a 1200 MPa grade high-strength and high-toughness gas shielded welding wire.

[0088] Comparative Example 1 - Comparative Example 8

[0089] The chemical compositions of the welding wires in Comparative Example 1 - Comparative Example 8 are shown in Table 1 respectively.

[0090] The preparation methods of the welding wires in Comparative Example 1 - Comparative Example 8 are the same as those in Example 1.

[0091] The compositions of the 1200 MPa grade high-strength and high-toughness gas shielded welding wires prepared in each example and the welding wires prepared in each comparative example are shown in Table 1 respectively.

[0092] Table 1 Chemical composition of welding wire (by mass percentage)

[0093]

[0094]

[0095] Among the 1200 MPa grade high-strength and high-toughness gas shielded welding wires prepared in each example and the welding wires prepared in Comparative Example 7, the sum of the mass percentages of Zr and Re / the mass percentage of B (abbreviated as (ω Zr +ω Re ) / ω B ) is shown in Table 2.

[0096] Table 2 (ω Zr +ω Re ) / ω B

[0097] Group <![CDATA[(ω Zr +ω Re ) / ω B > Example 1 7.5 Example 2 7.8 Example 3 7.5 Example 4 10 Example 5 5.8 Comparative Example 7 15

[0098] Experimental Example

[0099] The 1200 MPa grade high-strength and high-toughness gas shielded welding wires prepared by each embodiment and the welding wires prepared by each comparative example were used to perform TIG welding on 1200 MPa grade high-strength steel respectively. The welding process parameters are shown in Table 3, and post-weld heat treatment was carried out at 300 °C for 2 h.

[0100] Table 3 Welding process parameters

[0101]

[0102] The mechanical properties of the weld metals obtained after welding in each embodiment and each comparative example are shown in Table 4.

[0103] Among them, the impact absorption energy was tested according to the national standard GB / T 2650-2008, and three specimens were taken respectively, so there are three groups of test results.

[0104] Table 4 Test results of the mechanical properties of each weld metal

[0105]

[0106] It can be seen from Table 4 that in the present invention, by adding B, Zr and Re to the wire composition and strictly controlling (ω Zr +ω Re ) / ω B , the tensile strength of the weld metals prepared in each embodiment is greater than 1200 MPa, and the low-temperature impact absorption energy at -40 °C is greater than 47 J.

[0107] However, the tensile strength of the weld metals prepared in Comparative Example 1 and Comparative Example 2 without B, Zr and Re is far lower than 1200 MPa, and the low-temperature impact absorption energy at -40 °C is far less than 47 J.

[0108] The tensile strength and low-temperature toughness of the weld metals prepared in Comparative Example 3, Comparative Example 4 and Comparative Example 5 without B, Zr and Re respectively cannot meet the index requirements.

[0109] The weld metal prepared in Comparative Example 6 with the elemental composition not meeting the requirements has good tensile properties, but excessive Zr reduces the low-temperature toughness of the weld metal.

[0110] (ω Zr +ω Re ) / ω B exceeding 10, the weld metal prepared in Comparative Example 7 has good tensile and impact properties, but there are 1-2 mm cracks in the side bend test. See Figure 1 shown, which is the side bend test result of the welded joint obtained after TIG welding with the 1200 MPa grade high-strength and high-toughness gas shielded welding wire of Example 1. See Figure 2As shown, it is the side bend test result of the welded joint obtained after TIG welding with the welding wire of Comparative Example 7. It can be seen that Figure 2 there are multiple cracks. While Figure 1 there are no cracks.

[0111] The tensile properties of the weld metal prepared by Comparative Example 8 with a higher B content are lower, and the low-temperature impact toughness fluctuates greatly, not meeting the index requirements.

[0112] In summary, the present invention introduces B, Zr and Re, and controls (ω Zr +ω Re ) / ω B ≤10, which can improve the morphology and quantity of the precipitates in the low-temperature impact fracture dimples, increase the absorption energy of the weld metal for ductile fracture caused by microvoid coalescence under the action of impact load, and thus improve the low-temperature toughness of the weld metal. By regulating the contents of Si, Mn, Cr, Ni, and Mo in the main alloy components of the welding wire, the temperature of the transformation from austenite to ferrite is reduced, the quantity of proeutectoid ferrite is decreased, and compounds formed by adding Ti and Al elements are used as heterogeneous nucleation sites, so that more austenite is transformed into acicular ferrite, improving the strength and toughness of the weld metal.

[0113] Although the present invention has been illustrated and described with specific embodiments, it should be realized that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; those of ordinary skill in the art should understand that: without departing from the spirit and scope of the present invention, the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such replacements and modifications belonging to the scope of the present invention are included in the appended claims.

Claims

1. 1200MPa grade high strength and high toughness gas shielded welding wire, characterized by: Comprising the following components by mass percentage: C 0.06% to 0.12%, Si 0.2% to 0.6%, Mn 1.6% to 2.5%, S≤0.005%, P≤0.008%, Cr 0.3% to 0.8%, Ni 2.5% to 4.5%, Mo 0.6% to 1.2%, Ti 0.03% to 0.15%, Al 0.02% to 0.05%, B 0.004% to 0.012%, Zr 0.02% to 0.04%, Re 0.02% to 0.05%, and the balance is Fe and unavoidable impurities; Wherein, the Re includes Y and Ce; The sum of the mass percentages of the Zr and the Re / the mass percentage of the B is ≤10.

2. The 1200MPa high-strength and high-toughness gas shielded welding wire according to claim 1, characterized in that: The 1200MPa grade high-strength and high-toughness gas shielded welding wire comprises the following components in mass percentage: C 0.08%-0.10%, Si 0.20%-0.45%, Mn 1.8%-2.2%, S≤0.005%, P≤0.008%, Cr 0.5%-0.7%, Ni 3.2%-4.2%, Mo 0.8%-1.2%, Ti 0.05%-0.10%, Al 0.02%-0.04%, B 0.004%-0.012%, Zr 0.02%-0.04%, Re 0.02%-0.04%, and the balance is Fe and unavoidable impurities.

3. The 1200MPa high-strength and high-toughness gas shielded welding wire according to claim 1, characterized in that: The sum of the mass percentages of the Zr and the Re / the mass percentage of the B is 5-10.

4. The 1200MPa high-strength and high-toughness gas shielded welding wire according to claim 1, characterized in that: The mass ratio of the Y to the Ce is 25:

75.

5. The method for preparing the 1200MPa high-strength and high-toughness gas shielded welding wire according to any one of claims 1 to 4, characterized in that: The steps include: The raw materials are subjected to vacuum induction smelting, then electroslag remelting and refining, and then the ingots are hot rolled to obtain wire rods; After grinding and short-time annealing, the wire rod is roller-drawn to obtain the 1200MPa-grade high-strength and high-toughness gas shielded welding wire.

6. The method for preparing the 1200MPa high-strength and high-toughness gas shielded welding wire according to claim 5, characterized in that: The temperature of the short-time annealing is 750-800° C., and the holding time is 0.5-1.5 h.

7. The method for preparing the 1200MPa high-strength and high-toughness gas shielded welding wire according to claim 5, characterized in that: The diameter of the wire rod is 5.5 mm, and the drawing is performed in 9 passes, wherein the drawing rate of the first pass is 0.8-1.2 m / min, the drawing rates of the first four passes increase by 13%-17% pass by pass, the drawing rates of the last five passes are the same as the drawing rate of the fourth pass, and the last pass is eye die drawing, so as to obtain the 1200 MPa grade high-strength and high-toughness gas shielded welding wire with a diameter of 1.2 mm.

8. Use of the 1200MPa high-strength and high-toughness gas shielded welding wire as claimed in any one of claims 1 to 4 in welding steel.

9. The use of the 1200MPa high-strength and high-toughness gas shielded welding wire in welding steel according to claim 8, characterized in that: The welding current is 220-280A, the welding voltage is 24-30V, the welding speed is 350-400mm / min, the flow rate of the shielding gas used in the welding is 18-22L / min, the preheating temperature of the base material for welding is ≥100°C, the interlayer temperature of the welding is 120-150°C, and post-heat treatment is performed at 270-320°C after welding.

10. The use of the 1200MPa high-strength and high-toughness gas shielded welding wire in welding steel according to claim 9, characterized in that: The protective gas includes argon and carbon dioxide in a volume ratio of 85-90:10-15.

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