Wire rod for high-strength gas shielded welding wire suitable for pickling-free drawing and preparation method of wire rod

Abstract

The invention discloses a wire rod for a high-strength gas shielded welding wire suitable for pickling-free drawing and a preparation method of the wire rod, and relates to the technical field of steel production, and the wire rod comprises the following chemical components in percentage by mass: 0.05-0.12% of C, 0.70-0.90% of Si, 1.60-1.90% of Mn, less than or equal to 0.010% of P, less than or equal to 0.010% of S, 0.30-0.50% of Cr, 2.10-2.50% of Ni, less than or equal to 0.10% of Cu, 0.50-0.70% of Mo, 0.04-0.12% of Ti, less than or equal to 0.002% of B, less than or equal to 0.02% of V, less than or equal to 0.02% of Nb, less than or equal to 0.02% of Zr, less than or equal to 0.02% of Al, according to the method, pickling-free drawing of the wire rod for the high-strength gas shield welding wire is achieved, a traditional online pickling process oxide skin removing mode is replaced, the pickling cost and energy consumption are reduced, and meanwhile environment-friendly upgrading of the industry chain is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, in particular to a wire rod for high-strength gas shielded welding wire suitable for pickling-free drawing and a preparation method thereof. Background Art

[0002] For a long time, domestic steel companies have carried out extensive development of medium and thick steel plates for high-strength steel. The grades of high-strength steel plates have exceeded 1100MPa and 1300MPa, and the product technology research for various application scenarios is also relatively advanced. However, the research on welding materials for matching welding wires for high-strength steel plates has progressed slowly, resulting in the lack of matching welding materials after the development of many high-end steel products or being forced to purchase imported high-end welding materials at high prices.

[0003] In the high-strength gas shielded welding wire component system, the strengthening mechanism of high Si+CrNiMo is generally adopted. The high Si component design is helpful for deoxidation of the molten pool metal, improving strength and toughness, reducing the oxidation of Ni and Cr elements in the transition to the weld, and improving the fluidity of the molten pool. However, the high silicon component design has a negative impact on the exfoliation of the wire rod oxide scale, and the irregular FeO / Fe2SiO4 phase is easily formed on the surface of the matrix, and the iron oxide scale begins to appear on the surface of the wire rod and is embedded in the matrix. When Si, Cr, and Ni are added in combination, the physical exfoliation of the oxide scale will be further deteriorated, and the concavoconvexity of the oxide scale / matrix interface will be deteriorated. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the disadvantages of the prior art and provide a wire rod for high-strength gas shielded welding wire suitable for pickling-free drawing and a preparation method thereof.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows: A wire rod for high-strength gas shielded welding wire suitable for pickling-free drawing, the chemical composition of which includes, by mass percentage, C: 0.05-0.12%, Si: 0.70-0.90%, Mn: 1.60-1.90%, P: ≤0.010%, S: ≤0.010%, Cr: 0.30-0.50%, Ni: 2.10-2.50%, Cu: ≤0.10%, Mo: 0.50-0.70%, Ti: 0.04-0.12%, B: ≤0.002%, V: ≤0.02%, Nb: ≤0.02%, Zr: ≤0.02%, Al: ≤0.02%, As: ≤0.007%, N: ≤0.006%, and the balance is Fe and unavoidable impurities.

[0006] As a preferred embodiment of the high-strength gas shielded welding wire suitable for pickling-free drawing of the present invention, the iron oxide structural components of the wire rod are, from the substrate side to the outside, an alloy-enriched layer, Fe 1-xO, Fe3O4 and Fe2O3 layers, and Fe 1-x The O+Fe3O4 layer accounts for more than 63%.

[0007] The present invention also provides a method for preparing a wire rod for high-strength gas shielded welding wire suitable for pickling-free drawing, which comprises in sequence: converter / electric furnace smelting, LF furnace refining, VD furnace refining, continuous casting, billet chamfering, heating, rolling, and cooling.

[0008] As a preferred embodiment of the method for preparing high-strength gas shielded welding wire suitable for pickling-free drawing according to the present invention, the steel-making conditions of the converter / electric furnace smelting are: C content is 0.05%, P content is 0.04%, and the steel-making temperature is 1635°C.

[0009] As a preferred embodiment of the method for preparing high-strength gas shielded welding wire suitable for pickling-free drawing according to the present invention, the steel-making conditions of the converter / electric furnace smelting are: C content is 0.05%, P content is 0.04%, and the steel-making temperature is 1635°C.

[0010] As a preferred embodiment of the method for preparing high-strength gas shielded welding wire suitable for pickling-free drawing according to the present invention, the order of adding materials in the converter / electric furnace smelting steelmaking process is: deoxidizer, alloy, modified refined slag, and lime.

[0011] As a preferred solution of the method for preparing high-strength gas shielded welding wire suitable for pickling-free drawing according to the present invention, the target basicity of the LF refining furnace refining process is less than or equal to 2.5, and the white slag time is greater than or equal to 30 minutes.

[0012] As a preferred embodiment of the method for preparing high-strength gas shielded welding wire suitable for pickling-free drawing according to the present invention, the ultimate vacuum time of the VD furnace refining is greater than or equal to 10 minutes, and the static stirring time is greater than or equal to 10 minutes.

[0013] As a preferred solution of the method for preparing high-strength gas shielded welding wire suitable for pickling-free drawing according to the present invention, the superheat degree of the continuous casting process is 24° C. and the drawing speed is 2.1 m / min.

[0014] As a preferred embodiment of the method for preparing high-strength gas shielded welding wire suitable for pickling-free drawing described in the present invention, the heating process adopts a walking-beam heating furnace, the preheating section temperature is 580°C, the heating section temperature is 880°C, the heating section temperature is 1030°C, and the soaking section temperature is 1180°C.

[0015] As a preferred embodiment of the method for preparing high-strength gas shielded welding wire suitable for pickling-free drawing according to the present invention, the starting temperature of the rolling process is 1040°C, the final rolling temperature is 930°C, and the wire laying temperature is 930°C.

[0016] The beneficial effects of the present invention are: (1) The present invention realizes pickling-free drawing of wire rods for high-strength gas shielded welding wires, replacing the traditional online pickling process for removing oxide scales, saving pickling costs and energy consumption while promoting environmental protection upgrades in the industrial chain.

[0017] (2) The high-strength gas shielded welding wire wire rod prepared by the present invention has a tensile strength of ≤1200MPa, an elongation of ≥15%, and a cross-sectional shrinkage of ≥58%.

[0018] (3) The high-strength gas shielded welding wire prepared by the present invention has an iron oxide scale thickness of ≥15um, an iron oxide scale embedding depth of ≤12um, and an iron oxide structural component, from the substrate side to the outside, which is an alloy enriched layer, Fe 1-x O, Fe3O4 and Fe2O3 layers, the Fe 1-x The O+Fe3O4 layer accounts for more than 63%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0020] Figure 1 This is a schematic diagram of the typical structure of oxide scale; Figure 2 This is a schematic diagram of the iron oxide scale of the wire rod for high-strength gas shielded welding wire suitable for pickling-free drawing prepared in this embodiment. DETAILED DESCRIPTION

[0021] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific implementation modes and in combination with the accompanying drawings.

[0022] The embodiment of the present application provides a high-strength gas shielded welding wire wire rod suitable for pickling-free drawing, and its chemical composition includes, by mass percentage: C: 0.05-0.12%, Si: 0.70-0.90%, Mn: 1.60-1.90%, P: ≤0.010%, S: ≤0.010%, Cr: 0.30-0.50%, Ni: 2.10-2.50%, Cu: ≤0.10%, Mo: 0.50-0.70%, Ti: 0.04-0.12%, B: ≤0.002%, V: ≤0.02%, Nb: ≤0.02%, Zr: ≤0.02%, Al: ≤0.02%, As: ≤0.007%, N: ≤0.006%, and the balance is Fe and unavoidable impurities.

[0023] Generally speaking, there are three types of scale in the rolling process of welding wire steel ingots. During the heating process of the ingot in the heating furnace, the ingot comes into contact with oxygen at high temperature, and a thick layer of scale is formed on the surface, which is called primary scale, and is removed by high-pressure water descaling. During the rolling process, the steel temperature exceeds 900 ° C, and the surface continues to oxidize, forming secondary scale. After rolling, the wire rod is generally produced by the slow cooling process. During the cooling process of the Stelmor slow cooling line, the tertiary scale is generated and further structural transformation occurs. Therefore, the tertiary scale affects the final scale thickness on the surface of the wire rod. Reaction equation: 2Fe+O2=2FeO; 6FeO+O2=2Fe3O4; 4Fe3O4+O2=6Fe2O3.

[0024] The structure of the three-layer iron oxide scale includes a thick inner layer of FeO (ferrous oxide), a thin middle layer of Fe3O4, and a very thin surface layer of Fe2O3. The red rust on the surface is the manifestation of the surface Fe2O3. FeO is gray-blue at room temperature, has good plasticity and deformation ability at high temperature, and is easy to peel off. Fe3O4 is black and Fe2O3 is red. They have good adhesion at room temperature. The proportion of FeO layer to Fe3O4 layer is too small, which is not conducive to mechanical peeling. High-strength welding wire contains alloys such as Si and Ni, and an alloy enrichment layer will be formed between the matrix and the inner oxide scale.

[0025] High Si welding wire steel, at high temperature, the FeO on the surface of the high Si steel billet and the billet matrix combine to easily generate oxide Fe2SiO4 (ferrous silicate, with a high Si content, called a silicon-rich layer). After solidification, the viscosity of the oxide scale increases, which is not easy to remove after high-pressure water descaling, and remains on the surface of the wire rod, resulting in it being left on the surface after drawing. Increasing the heating temperature will hinder the diffusion of oxygen into the silicon-rich layer, reduce the proportion of SiO2, reduce the proportion of ferrous silicate, ensure descaling pressure, and avoid ferrous silicate residue. Reaction formula: Si+O2=SiO2, 2FeO+SiO2= Fe2SiO4.

[0026] Typical structure of oxide scale Figure 1 A steel is low Si and no alloy, the oxide scale is the smoothest and the thickest, which is conducive to physical peeling; B steel is high Si and no alloy, and contains Si to form a Si-rich layer, which hinders diffusion, reduces the thickness of the oxide scale, and reduces the flatness, so it can be physically peeled; C steel is high Si and high alloy, forming an alloy-rich layer, which further hinders diffusion, and the oxide scale extends inward in an anchor shape, with the worst flatness, and is suitable for pickling and descaling.

[0027] See also Figure 2 In this embodiment, the oxide scale thickness of the wire rod is ≥15um, and the embedded depth of the oxide scale of the wire rod is ≤12um. The iron oxide structural components of the wire rod are, from the substrate side to the outside, the alloy enriched layer, Fe 1-x O, Fe3O4 and Fe2O3 layers, the Fe 1-x The O+Fe3O4 layer accounts for more than 63%.

[0028] The embodiment of the present application also provides a method for preparing a wire rod for high-strength gas shielded welding wire suitable for pickling-free drawing, which comprises in sequence: converter / electric furnace smelting, LF furnace refining, VD furnace refining, continuous casting, billet chamfering, heating, rolling, and cooling.

[0029] Among them, the tapping conditions of converter / electric furnace smelting are: C content is 0.05%, P content is 0.04%, and tapping temperature is 1635℃. The order of adding materials in the tapping process is: deoxidizer → alloy → modified refined slag → lime. Silicon manganese alloy, lime 5kg / t, and modified refined slag 3kg / t are added in the tapping process.

[0030] In the LF refining furnace refining process, a small amount of lime is added according to the slag condition and sulfur content. The target alkalinity is controlled to be less than or equal to 2.5, and the white slag time is greater than or equal to 30 minutes.

[0031] The ultimate vacuum time of VD furnace refining is greater than or equal to 10 minutes, and the static stirring time is greater than or equal to 10 minutes.

[0032] The superheat of the continuous casting process (150x150mm billet) is 24℃, the pulling speed is 2.1m / min, the specific water volume adopts weak cooling mode, the continuous casting adopts protective pouring, and the pouring is operated with argon.

[0033] In the billet chamfering process, the billet is rolled after the corners are chamfered to ensure that the corners are polished cleanly without residue and the metal transition at the corners is smooth.

[0034] The heating process uses a walking-beam heating furnace, with a preheating section temperature of 580°C, a heating section temperature of 880°C, a second heating section temperature of 1030°C, and a soaking section temperature of 1180°C.

[0035] The starting rolling temperature of the rolling process is 1040°C, the final rolling temperature is 930°C, and the wire drawing temperature is 930°C. After delayed cooling on the Stelmor wire, a φ5.5mm wire rod is obtained.

[0036] The tensile strength of the prepared wire rod is ≤1200MPa, the elongation is ≥15%, and the cross-sectional shrinkage is ≥58%. The specific mechanical property values ​​are shown in Table 1.

[0037]

[0038] Table 1 Therefore, the technical solution of the present application realizes pickling-free drawing of wire rods for high-strength gas shielded welding wire, replacing the traditional online pickling process for removing oxide scale, saving pickling costs and energy consumption while promoting environmental protection upgrades in the industrial chain.

[0039] In addition to the above embodiments, the present invention may also have other implementation modes; any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A wire rod for high-strength gas shielded welding wire suitable for pickling-free drawing, characterized in that: Its chemical composition, by mass percentage, includes: C: 0.05-0.12%, Si: 0.70-0.90%, Mn: 1.60-1.90%, P: ≤0.010%, S: ≤0.010%, Cr: 0.30-0.50%, Ni: 2.10-2.50%, Cu: ≤0.10%, Mo: 0.50-0.70%, Ti: 0.04-0.12%, B: ≤0.002%, V: ≤0.02%, Nb: ≤0.02%, Zr: ≤0.02%, Al: ≤0.02%, As: ≤0.007%, N: ≤0.006%, and the balance is Fe and unavoidable impurities.

2. The high-strength gas shielded welding wire wire rod suitable for pickling-free drawing according to claim 1, characterized in that: The iron oxide structural components of the wire rod are, from the substrate side to the outside, an alloy-enriched layer, Fe 1-x O, Fe3O4 and Fe2O3 layers, and Fe 1-x The O+Fe3O4 layer accounts for more than 63%.

3. A method for preparing a high-strength gas shielded welding wire wire rod suitable for pickling-free drawing according to claim 1 or 2, characterized in that: Including in order: Converter / electric furnace smelting, LF furnace refining, VD furnace refining, continuous casting, billet chamfering, heating, rolling and cooling.

4. The method for preparing a high-strength gas shielded welding wire suitable for pickling-free drawing according to claim 3, characterized in that: The steel-tapping conditions of the converter / electric furnace smelting are: C content is 0.05%, P content is 0.04%, and the steel-tapping temperature is 1635°C.

5. The method for preparing a high-strength gas shielded welding wire suitable for pickling-free drawing according to claim 3, characterized in that: The order of adding materials in the converter / electric furnace steelmaking process is: deoxidizer, alloy, modified refined slag, and lime.

6. The method for preparing a high-strength gas shielded welding wire suitable for pickling-free drawing according to claim 3, characterized in that: The target basicity of the LF refining furnace refining process is less than or equal to 2.5, and the white slag time is greater than or equal to 30 minutes.

7. The method for preparing a high-strength gas shielded welding wire suitable for pickling-free drawing according to claim 3, characterized in that: The ultimate vacuum time of the VD furnace refining is greater than or equal to 10 minutes, and the static stirring time is greater than or equal to 10 minutes.

8. The method for preparing a high-strength gas shielded welding wire suitable for pickling-free drawing according to claim 3, characterized in that: The superheat degree of the continuous casting process is 24° C. and the casting speed is 2.1 m / min.

9. The method for preparing a high-strength gas shielded welding wire suitable for pickling-free drawing according to claim 3, characterized in that: The heating process adopts a walking beam heating furnace, with a preheating section temperature of 580°C, a heating section temperature of 880°C, a second heating section temperature of 1030°C, and a soaking section temperature of 1180°C.

10. The method for preparing a high-strength gas shielded welding wire suitable for pickling-free drawing according to claim 3, characterized in that: The rolling process has a starting rolling temperature of 1040°C, a final rolling temperature of 930°C, and a wire laying temperature of 930°C.

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