Welding wire and welding method for laser wire filling welding of Al-Si coating hot forming steel plate

Abstract

The invention relates to the technical field of laser wire filling welding, and particularly discloses a welding wire for laser wire filling welding of an Al-Si coating hot forming steel plate and a welding method. The welding wire comprises the following components in percentage by mass: (0.0025-0.003) * ([C1] + [Al]) + a / 1120)% of carbon (C), 2.70-3.40% of manganese (Mn), 4.10-5.65% of nickel (Ni), 0.022-0.045% of titanium (Ti), (0.004-0.005) * [Al] + a / 1045)% of strontium (Sr), 0.002-0.005% of boron (B), less than or equal to 0.015% of phosphorus (P), less than or equal to 0.005% of sulfur (S) and the balance of iron and inevitable impurities. According to the welding wire composition system, the adverse effect of an Al-Si coating on a welding seam is effectively reduced, and the welding seam keeps high strength and good plasticity and toughness at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of laser wire-filling welding, and in particular to a welding wire and a welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates. Background Art

[0002] The following content in the background technology refers only to the information related to the present invention understood by the inventor, and is intended to increase the understanding of the present invention by explaining some basic technical knowledge related to the present invention. This information does not necessarily constitute knowledge known to ordinary technicians in this field.

[0003] During the hot forming process, hot-formed steel is prone to form an oxide layer on the surface due to high-temperature oxidation, which affects the surface quality, dimensional accuracy and subsequent processing of the steel plate. In order to overcome the above problems, ArcelorMittal Group proposed a solution in 1999 to hot-dip an Al-Si coating on the surface of hot-formed steel, which can form a continuous, uniform and dense protective film on the surface of the steel plate. At the same time, the protective film formed by the Al-Si coating can still maintain a good coating morphology at high temperatures, thereby isolating the steel plate from oxygen during the hot forming process of the steel plate and reducing the oxidation of the steel plate surface.

[0004] However, when laser welding is performed on such steel plates with Al-Si coating, the coating around the weld will melt and enter the weld pool, and the Al element therein will promote the formation of ferrite phases. These ferrite phases will no longer undergo phase changes during the subsequent cooling process and will remain in the weld. Due to the low strength of ferrite, the overall mechanical strength of the weld will decrease, making the weld a weak point that is prone to fracture. For this reason, the prior art currently generally adopts a method of adding austenite-enlarging elements to the welding wire to reduce the formation of ferrite, so that the formed austenite phase is transformed into a high-strength martensite phase during the subsequent cooling process, thereby maintaining the weld with high strength. However, this method will result in poor plastic toughness of the weld, and it is prone to brittle fracture when subjected to the impact of external loads. Summary of the invention

[0005] In view of the above problems, the present invention provides a welding wire and a welding method for laser wire welding of Al-Si coated hot-formed steel plates, which effectively reduces the adverse effects of the Al-Si coating on the weld, and enables the weld to maintain high strength and good plastic toughness. Specifically, the technical solution of the present invention is as follows.

[0006] First, the present invention provides a welding wire for laser wire welding of Al-Si coated hot-formed steel plates, which comprises the following components by mass percentage: carbon (C) = ((0.0025~0.003) × ([C 1]+[Al])+a / 1120)%, manganese (Mn) = 2.70~3.40%, nickel (Ni) = 4.10~5.65%, titanium (Ti) = 0.022~0.045%, strontium (Sr) = ((0.004~0.005)×[Al]+a / 1045)%, boron (B) = 0.002~0.005%, phosphorus (P) ≤ 0.015%, sulfur (S) ≤ 0.005%, and the balance is iron and unavoidable impurities. Wherein: the [C 1 ] is the percentage of carbon in the Al-Si coated hot-formed steel plate, [Al] is the content of aluminum in the Al-Si coating, and a is the coating amount of the Al-Si coating on the surface of the hot-formed steel plate, in g / m 2 .

[0007] Furthermore, the diameter of the welding wire is 0.5-2 mm, and can also be made into other suitable specifications as needed.

[0008] Secondly, the present invention provides a welding method for laser wire welding of Al-Si coated hot-formed steel plates, comprising the following steps: groove the surfaces to be welded of two steel plates, butt them together and fix them with a clamp, and there is a gap between the surfaces to be welded. Then, the welding wire of the present invention is placed in the groove, and laser welding is used to perform welding in an oxygen-isolating environment formed by a protective atmosphere. While welding, the steel plates are moved into a heat-insulating furnace by a crawler to perform heat-insulating treatment on the welds, and after completion, the welds are quenched.

[0009] Furthermore, the width of the gap is D=0.1×(d 1 +d 2 ) mm. Wherein: the d 1 ,d 2 are the thicknesses of the two steel plates respectively, in mm. Optionally, the angle of the groove is 10-45°.

[0010] Furthermore, the diameter of the welding wire is 2.5 to 3.5 times the gap width.

[0011] Furthermore, the power of the laser welding is 4000-7500 W, the welding speed is 1-2 m / min, the wire feeding speed is synchronized with the welding speed, and the laser spot diameter is 0.5-1.5 mm.

[0012] Further, the protective atmosphere includes at least one of argon, helium, etc. Optionally, the protective atmosphere has a delivery flow rate of 10-25 L / min.

[0013] Furthermore, the temperature of the heat preservation treatment is M s -(50~70)℃. Ms =535-317[C]-33[Mn]-17[Ni]. The [C], [Mn], and [Ni] are the percentages of the corresponding elements in the welding wire.

[0014] Further, the heat preservation treatment time is 120-180s. Optionally, the quenching treatment includes any one of water quenching, salt water quenching and the like.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1) The welding wire for Al-Si coated hot-formed steel plate of the present invention fully considers the influence of the aluminum element in the Al-Si coating on the mechanical properties of the weld, and adopts a new welding wire component system related to the aluminum element, which effectively reduces the adverse effects of the Al-Si coating on the weld, so that the weld maintains high strength and good plasticity and toughness at the same time. (2) Strontium elements related to the aluminum content in the Al-Si coating are added to the welding wire of the present invention, which helps to transform the needle-shaped eutectic phase formed by the aluminum element and the silicon element entering the weld into a spherical or elliptical structure, thereby improving the strength and plasticity and toughness of the weld structure. (3) The present invention improves the weld after welding. M s The heat preservation treatment is carried out at a temperature of -(50~70)℃. During this process, the austenite phase in the weld is transformed into martensite, and the excess carbon, manganese, nickel and other elements in solid solution are migrated into the residual austenite phase, so that this part of the austenite phase can be retained in the subsequent quenching process. These residual austenites in the weld absorb energy and undergo induced phase transformation when subjected to external loads, and then transform into the martensite phase, thereby ensuring the mechanical strength of the weld and improving the plastic toughness of the weld, so that the weld of the Al-Si coated hot-formed steel plate maintains good comprehensive mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0017] Figure 1 The following is a diagram of a welded specimen used for tensile strength and elongation testing in Example 1.

[0018] Figure 2 The following is a diagram of a welded specimen used for tensile strength and elongation testing in Example 2.

[0019] Figure 3 The following is a diagram of a welded specimen used for tensile strength and elongation testing in Example 3.

[0020] Figure 4The following is a diagram of a welded specimen used for tensile strength and elongation testing in Example 4.

[0021] Figure 5 The following is a diagram of a welded specimen used for tensile strength and elongation testing in Example 5.

[0022] Figure 6 The following is a picture of the welding specimen used for tensile strength and elongation after fracture test in Example 6.

[0023] Figure 7 The following is a picture of the welding specimen used for tensile strength and elongation after fracture test in Example 7.

[0024] Figure 8 The following is a picture of the welding specimen used for tensile strength and elongation after fracture test in Example 8.

[0025] Fig. 9 The following is a picture of the welding specimen used for tensile strength and elongation after fracture test in Example 9. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific embodiments. It should be understood that these embodiments and materials are for demonstration purposes only and are not all embodiments. All other embodiments obtained by ordinary technicians in this field based on these embodiments without creative work are within the scope of protection of the present invention. The technical solution of the present invention is further described according to the accompanying drawings and specific embodiments of the specification.

[0027] In the following examples, the base material composition of the Al-Si coated hot-formed steel is shown in the following table, and the Al-Si coating coating amount a on its surface is 47 g / m 2 , and the mass percentage of [Al] element in the Al-Si coating is 91.04%; .

[0028] Example 1 A welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates comprises the following steps: (1) In terms of mass percentage, the welding wire used in this embodiment includes the following components: carbon (C) = 0.0028×([C 1 ]+[Al])+a / 1120≈0.30%, manganese (Mn) = 2.8%, nickel (Ni) = 4.57%, titanium (Ti) = 0.033%, strontium (Sr) = 0.005×[Al]+a / 1045≈0.5%, boron (B) = 0.004%, phosphorus (P) = 0.011%, sulfur (S) = 0.003%, and the remainder is iron and unavoidable impurities.

[0029] (2) The surfaces to be welded of two hot-formed steel plates, each with a thickness of 2 mm, are beveled and butt-jointed and fixed with a clamp, with a gap having a width of D = 0.1 × (2 + 2) mm = 0.4 mm between the surfaces to be welded. The bevel is Y-shaped and has a bevel angle of 30°.

[0030] (3) The welding wire of this embodiment with a diameter of 1.2 mm is placed in the groove, and then argon gas is used as the protective gas (the delivery flow rate is 15 L / min), and the laser welding method is used for welding. The welding power is set to 6000 W, the welding speed is set to 1 m / min, and the laser spot diameter is set to 0.8 mm. The wire feeding speed of the welding wire is synchronized with the welding speed. While welding, the steel plate is moved into the insulation furnace by the crawler to insulate the weld. The insulation temperature is M s -70 = 200 ° C, M s =535-317[C]-33[Mn]-17[Ni]≈270℃, and the heat preservation time is 120s. After completion, the weld is water quenched, and the laser welding of the Al-Si coated hot-formed steel plate is completed.

[0031] The hot-formed steel plate after welding in this embodiment was processed into a tensile specimen by a wire cutting machine, and then a tensile test was carried out using a WDW-100 universal tensile testing machine, with the strain rate set to 0.1s -1 The test results are shown in the following table. Figure 1 As shown, it can be seen that the fracture position is located on the parent material, and combined with the test results of the tensile test, it is shown that the weld after welding has both high strength and good plasticity and toughness; .

[0032] Example 2 A welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates comprises the following steps: (1) In terms of mass percentage, the welding wire used in this embodiment includes the following components: carbon (C) = 0.003×([C 1 ]+[Al])+a / 1120≈0.32%, manganese (Mn) = 2.7%, nickel (Ni) = 5.65%, titanium (Ti) = 0.045%, strontium (Sr) = 0.004×[Al]+a / 1045≈0.41%, boron (B) = 0.002%, phosphorus (P) = 0.013%, sulfur (S) = 0.005%, and the remainder is iron and unavoidable impurities.

[0033] (2) The surfaces to be welded of two hot-formed steel plates, each with a thickness of 2 mm, are beveled and butt-jointed and fixed with a clamp, with a gap having a width of D = 0.1 × (2 + 2) mm = 0.4 mm between the surfaces to be welded. The bevel is Y-shaped and has a bevel angle of 45°.

[0034] (3) The welding wire of this embodiment with a diameter of 1.4 mm is placed in the groove, and then argon gas is used as the protective gas (the delivery flow rate is 25 L / min), and the laser welding method is used for welding. The welding power is set to 7500 W, the welding speed is set to 2 m / min, and the laser spot diameter is set to 1.5 mm. The wire feeding speed of the welding wire is synchronized with the welding speed. While welding, the steel plate is moved into the insulation furnace by the crawler to insulate the weld. The insulation temperature is M s -50 = 198 ° C, M s =535-317[C]-33[Mn]-17[Ni]≈248℃, and the heat preservation time is 180s. After completion, the weld is water quenched, and the laser welding of the Al-Si coated hot-formed steel plate is completed.

[0035] The hot-formed steel plate after welding in this embodiment was processed into a tensile specimen by a wire cutting machine, and then a tensile test was carried out using a WDW-100 universal tensile testing machine, with the strain rate set to 0.1s -1 The test results are shown in the following table. Figure 2 As shown, it can be seen that the fracture position is located on the parent material, and combined with the test results of the tensile test, it is shown that the weld after welding has both high strength and good plasticity and toughness; .

[0036] Example 3 A welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates comprises the following steps: (1) In terms of mass percentage, the welding wire used in this embodiment includes the following components: carbon (C) = 0.0025×([C 1 ]+[Al])+a / 1120≈0.27%, manganese (Mn) = 3.4%, nickel (Ni) = 4.1%, titanium (Ti) = 0.022%, strontium (Sr) = 0.0045×[Al]+a / 1045≈0.45%, boron (B) = 0.005%, phosphorus (P) = 0.015%, sulfur (S) = 0.001%, and the remainder is iron and unavoidable impurities.

[0037] (2) The surfaces to be welded of two hot-formed steel plates, each with a thickness of 2 mm, are beveled and butt-jointed and fixed with a clamp, with a gap having a width of D = 0.1 × (2 + 2) mm = 0.4 mm between the surfaces to be welded. The bevel is Y-shaped and has a bevel angle of 10°.

[0038] (3) The welding wire of this embodiment with a diameter of 1.0 mm is placed in the groove, and then argon gas is used as the protective gas (the delivery flow rate is 10 L / min), and the laser welding method is used for welding. The welding power is set to 4000 W, the welding speed is set to 1.5 m / min, and the laser spot diameter is set to 0.5 mm. The wire feeding speed of the welding wire is synchronized with the welding speed. While welding, the steel plate is moved into the insulation furnace by the crawler to insulate the weld. The insulation temperature is M s -60 = 208 ° C, M s =535-317[C]-33[Mn]-17[Ni]≈268℃, and the heat preservation time is 140s. After completion, the weld is water quenched, and the laser welding of the Al-Si coated hot-formed steel plate is completed.

[0039] The hot-formed steel plate after welding in this embodiment was processed into a tensile specimen by a wire cutting machine, and then a tensile test was carried out using a WDW-100 universal tensile testing machine, with the strain rate set to 0.1s -1 The test results are shown in the following table. Figure 3 As shown, it can be seen that the fracture position is located on the parent material, and combined with the test results of the tensile test, it is shown that the weld after welding has both high strength and good plasticity and toughness; .

[0040] Example 4 A welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates comprises the following steps: (1) In terms of mass percentage, the welding wire used in this embodiment includes the following components: carbon (C) = 0.0028×([C 1 ]+[Al])≈0.256%, manganese (Mn) = 2.8%, nickel (Ni) = 4.57%, titanium (Ti) = 0.033%, strontium (Sr) = 0.005×[Al]≈0.455%, boron (B) = 0.004%, phosphorus (P) = 0.011%, sulfur (S) = 0.003%, and the remainder is iron and unavoidable impurities.

[0041] (2) The surfaces to be welded of two hot-formed steel plates, each with a thickness of 2 mm, are beveled and butt-jointed and fixed with a clamp, with a gap having a width of D = 0.1 × (2 + 2) mm = 0.4 mm between the surfaces to be welded. The bevel is Y-shaped and has a bevel angle of 30°.

[0042] (3) The welding wire of this embodiment with a diameter of 1.2 mm is placed in the groove, and then argon gas is used as the protective gas (the delivery flow rate is 15 L / min), and the laser welding method is used for welding. The welding power is set to 6000 W, the welding speed is set to 1 m / min, and the laser spot diameter is set to 0.8 mm. The wire feeding speed of the welding wire is synchronized with the welding speed. While welding, the steel plate is moved into the insulation furnace by the crawler to insulate the weld. The insulation temperature is M s -70 = 212 ° C, M s =535-317[C]-33[Mn]-17[Ni]≈282℃, and the heat preservation time is 120s. After completion, the weld is water quenched, and the laser welding of the Al-Si coated hot-formed steel plate is completed.

[0043] The hot-formed steel plate after welding in this embodiment was processed into a tensile specimen by a wire cutting machine, and then a tensile test was carried out using a WDW-100 universal tensile testing machine, with the strain rate set to 0.1s -1 The test results are shown in the following table. Figure 4 As shown, it can be seen that the fracture position is located at the weld, indicating that the mechanical properties of the weld are insufficient; .

[0044] Example 5 A welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates comprises the following steps: (1) In terms of mass percentage, the welding wire used in this embodiment includes the following components: carbon (C) = 0.003×([C 1 ]+[Al])+a / 1120≈0.32%, manganese (Mn) = 2.7%, nickel (Ni) = 5.65%, titanium (Ti) = 0.045%, boron (B) = 0.002%, phosphorus (P) = 0.013%, sulfur (S) = 0.005%, and the remainder is iron and unavoidable impurities.

[0045] (2) The surfaces to be welded of two hot-formed steel plates, each with a thickness of 2 mm, are beveled and butt-jointed and fixed with a clamp, with a gap having a width of D = 0.1 × (2 + 2) mm = 0.4 mm between the surfaces to be welded. The bevel is Y-shaped and has a bevel angle of 45°.

[0046] (3) The welding wire of this embodiment with a diameter of 1.4 mm is placed in the groove, and then argon gas is used as the protective gas (the delivery flow rate is 25 L / min), and the laser welding method is used for welding. The welding power is set to 7500 W, the welding speed is set to 2 m / min, and the laser spot diameter is set to 1.5 mm. The wire feeding speed of the welding wire is synchronized with the welding speed. While welding, the steel plate is moved into the insulation furnace by the crawler to insulate the weld. The insulation temperature is M s -50 = 198 ° C, M s =535-317[C]-33[Mn]-17[Ni]≈248℃, and the heat preservation time is 180s. After completion, the weld is water quenched, and the laser welding of the Al-Si coated hot-formed steel plate is completed.

[0047] The hot-formed steel plate after welding in this embodiment was processed into a tensile specimen by a wire cutting machine, and then a tensile test was carried out using a WDW-100 universal tensile testing machine, with the strain rate set to 0.1s -1 The test results are shown in the following table. Figure 5 As shown, it can be seen that the fracture position is located in the heat-affected zone near the weld, indicating that the mechanical properties of the weld are insufficient; .

[0048] Example 6 A welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates comprises the following steps: (1) In terms of mass percentage, the welding wire used in this embodiment includes the following components: carbon (C) = 0.0025×[C 1 ]+a / 1120≈0.043%, manganese (Mn) = 3.4%, nickel (Ni) = 4.1%, titanium (Ti) = 0.022%, strontium (Sr) = 0.0045×[Al]+a / 1045≈0.45%, boron (B) = 0.005%, phosphorus (P) = 0.015%, sulfur (S) = 0.001%, and the remainder is iron and unavoidable impurities.

[0049] (2) The surfaces to be welded of two hot-formed steel plates, each with a thickness of 2 mm, are beveled and butt-jointed and fixed with a clamp, with a gap having a width of D = 0.1 × (2 + 2) mm = 0.4 mm between the surfaces to be welded. The bevel is Y-shaped and has a bevel angle of 10°.

[0050] (3) The welding wire of this embodiment with a diameter of 1.0 mm is placed in the groove, and then argon gas is used as the protective gas (the delivery flow rate is 10 L / min), and the laser welding method is used for welding. The welding power is set to 4000 W, the welding speed is set to 1.5 m / min, and the laser spot diameter is set to 0.5 mm. The wire feeding speed of the welding wire is synchronized with the welding speed. While welding, the steel plate is moved into the insulation furnace by the crawler to insulate the weld. The insulation temperature is M s -60 = 280 ° C, M s =535-317[C]-33[Mn]-17[Ni]≈340℃, and the heat preservation time is 140s. After completion, the weld is water quenched, and the laser welding of the Al-Si coated hot-formed steel plate is completed.

[0051] The hot-formed steel plate after welding in this embodiment was processed into a tensile specimen by a wire cutting machine, and then a tensile test was carried out using a WDW-100 universal tensile testing machine, with the strain rate set to 0.1s -1 The test results are shown in the following table. Figure 6 As shown, it can be seen that the crack position is located at the weld, indicating that the mechanical properties of the weld are insufficient; .

[0052] Example 7 A welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates comprises the following steps: (1) In terms of mass percentage, the welding wire used in this embodiment includes the following components: carbon (C) = 0.003×([C 1 ]+[Al])+a / 1120≈0.32%, manganese (Mn) = 2.7%, titanium (Ti) = 0.045%, strontium (Sr) = 0.004×[Al]+a / 1045≈0.41%, boron (B) = 0.002%, phosphorus (P) = 0.013%, sulfur (S) = 0.005%, and the remainder is iron and unavoidable impurities.

[0053] (2) The surfaces to be welded of two hot-formed steel plates, each with a thickness of 2 mm, are beveled and butt-jointed and fixed with a clamp, with a gap having a width of D = 0.1 × (2 + 2) mm = 0.4 mm between the surfaces to be welded. The bevel is Y-shaped and has a bevel angle of 45°.

[0054] (3) The welding wire of this embodiment with a diameter of 1.4 mm is placed in the groove, and then argon gas is used as the protective gas (the delivery flow rate is 25 L / min), and the laser welding method is used for welding. The welding power is set to 7500 W, the welding speed is set to 2 m / min, and the laser spot diameter is set to 1.5 mm. The wire feeding speed of the welding wire is synchronized with the welding speed. While welding, the steel plate is moved into the insulation furnace by the crawler to insulate the weld. The insulation temperature is M s -50 = 295 ° C, M s =535-317[C]-33[Mn]-17[Ni]≈345℃, and the heat preservation time is 180s. After completion, the weld is water quenched, and the laser welding of the Al-Si coated hot-formed steel plate is completed.

[0055] The hot-formed steel plate after welding in this embodiment was processed into a tensile specimen by a wire cutting machine, and then a tensile test was carried out using a WDW-100 universal tensile testing machine, with the strain rate set to 0.1s -1 The test results are shown in the following table. Figure 7 As shown, it can be seen that the fracture position is located at the weld, indicating that the mechanical properties of the weld are insufficient; .

[0056] Example 8 A welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates comprises the following steps: (1) In terms of mass percentage, the welding wire used in this embodiment includes the following components: carbon (C) = 0.0025×([C 1 ]+[Al])+a / 1120≈0.27%, nickel (Ni) = 4.1%, titanium (Ti) = 0.022%, strontium (Sr) = 0.0045×[Al]+a / 1045≈0.45%, boron (B) = 0.005%, phosphorus (P) = 0.015%, sulfur (S) = 0.001%, and the remainder is iron and unavoidable impurities.

[0057] (2) The surfaces to be welded of two hot-formed steel plates, each with a thickness of 2 mm, are beveled and butt-jointed and fixed with a clamp, with a gap having a width of D = 0.1 × (2 + 2) mm = 0.4 mm between the surfaces to be welded. The bevel is Y-shaped and has a bevel angle of 10°.

[0058] (3) The welding wire of this embodiment with a diameter of 1.0 mm is placed in the groove, and then argon gas is used as the protective gas (the delivery flow rate is 10 L / min), and the laser welding method is used for welding. The welding power is set to 4000 W, the welding speed is set to 1.5 m / min, and the laser spot diameter is set to 0.5 mm. The wire feeding speed of the welding wire is synchronized with the welding speed. While welding, the steel plate is moved into the insulation furnace by the crawler to insulate the weld. The insulation temperature is M s -60 = 320 ° C, M s =535-317[C]-33[Mn]-17[Ni]≈380℃, and the heat preservation time is 140s. After completion, the weld is water quenched, and the laser welding of the Al-Si coated hot-formed steel plate is completed.

[0059] The hot-formed steel plate after welding in this embodiment was processed into a tensile specimen by a wire cutting machine, and then a tensile test was carried out using a WDW-100 universal tensile testing machine, with the strain rate set to 0.1s -1 The test results are shown in the following table. Figure 8 As shown, it can be seen that the fracture position is located in the heat-affected zone near the weld, indicating that the mechanical properties of the weld are insufficient; .

[0060] Example 9 A welding method for laser wire-filling welding of Al-Si coated hot-formed steel plates comprises the following steps: (1) In terms of mass percentage, the welding wire used in this embodiment includes the following components: carbon (C) = 0.0028×([C 1 ]+[Al])+a / 1120≈0.30%, manganese (Mn) = 2.8%, nickel (Ni) = 4.57%, titanium (Ti) = 0.033%, strontium (Sr) = 0.005×[Al]+a / 1045≈0.5%, boron (B) = 0.004%, phosphorus (P) = 0.011%, sulfur (S) = 0.003%, and the remainder is iron and unavoidable impurities.

[0061] (2) The surfaces to be welded of two hot-formed steel plates, each with a thickness of 2 mm, are beveled and butt-jointed and fixed with a clamp, with a gap having a width of D = 0.1 × (2 + 2) mm = 0.4 mm between the surfaces to be welded. The bevel is Y-shaped and has a bevel angle of 30°.

[0062] (3) The welding wire of this embodiment with a diameter of 1.2 mm is placed in the groove, and then argon gas is used as the protective gas (the delivery flow rate is 15 L / min), and the laser welding method is used for welding. The welding power is set to 6000 W, the welding speed is set to 1 m / min, and the laser spot diameter is set to 0.8 mm. The wire feeding speed of the welding wire is synchronized with the welding speed. After the welding is completed, the weld is water quenched, and the laser welding of the Al-Si coated hot-formed steel plate is completed.

[0063] The hot-formed steel plate after welding in this embodiment was processed into a tensile specimen by a wire cutting machine, and then a tensile test was carried out using a WDW-100 universal tensile testing machine, with the strain rate set to 0.1s -1 The test results are shown in the following table. Fig. 9 As shown, it can be seen that the fracture position is located at the weld, indicating that the mechanical properties of the weld are insufficient; .

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A welding wire for laser wire welding of Al-Si coated hot-formed steel plates, characterized in that: The welding wire comprises the following components in percentage by mass: C=((0.0025~0.003)×([C1]+[Al])+a / 1120)%, Mn=2.70~3.40%, Ni=4.10~5.65%, Ti=0.022~0.045%, Sr=((0.004~0.005)×[Al]+a / 1045)%, B=0.002~0.005%, P≤0.015%, S≤0.005%, and the remainder is iron and unavoidable impurities; wherein: [C1] is the percentage of carbon element in the Al-Si coated hot-formed steel plate, [Al] is the content of aluminum element in the Al-Si coating, and a is the coating amount of the Al-Si coating on the surface of the hot-formed steel plate, in g / m 2 .

2. The welding wire for laser wire welding of Al-Si coated hot-formed steel plates according to claim 1, characterized in that: The diameter of the welding wire is 0.5-2 mm.

3. A welding method for laser wire welding of Al-Si coated hot-formed steel plate, characterized in that: The method comprises the following steps: beveling the surfaces to be welded of two steel plates, butting them together and fixing them with a clamp, with a gap between the surfaces to be welded; then inserting the welding wire for laser wire welding of Al-Si coated hot-formed steel plates as claimed in claim 1 or 2 into the bevel; then welding is performed in an oxygen-isolating environment formed by a protective atmosphere by a laser welding method; while welding, the steel plates are moved into a heat-insulating furnace by a crawler to perform heat-insulating treatment on the welds; After completion, the weld can be quenched.

4. The welding method of Al-Si coated hot-formed steel plate by laser welding with wire filling according to claim 3, characterized in that: The width of the gap D=0.1×(d1+d2) mm; wherein: d1 and d2 are the thicknesses of two steel plates respectively, and the unit is mm; or, the angle of the groove is 10~45°.

5. The welding method of Al-Si coated hot-formed steel plate by laser welding with wire filling according to claim 3, characterized in that: The diameter of the welding wire is 2.5 to 3.5 times the width of the gap.

6. The welding method of Al-Si coated hot-formed steel plate by laser welding with wire filling according to claim 3, characterized in that: The power of the laser welding is 4000-7500 W, the welding speed is 1-2 m / min, the wire feeding speed is synchronized with the welding speed, and the laser spot diameter is 0.5-1.5 mm.

7. The welding method of Al-Si coated hot-formed steel plate by laser welding with wire filling according to claim 3, characterized in that: The protective atmosphere includes at least one of argon and helium; or, the delivery flow rate of the protective atmosphere is 10~25L / min.

8. The welding method of Al-Si coated hot-formed steel plate by laser welding with wire filling according to claim 3, characterized in that: The temperature of the heat preservation treatment is M s -(50~70)℃; wherein: M s =535-317[C]-33[Mn]-17[Ni]; the [C], [Mn], and Ni] are all percentages of the corresponding elements in the welding wire.

9. The welding method of Al-Si coated hot-formed steel plate by laser welding with wire filling according to claim 3, characterized in that: The time of the heat preservation treatment is 120-180s.

10. The welding method of laser wire welding of Al-Si coated hot-formed steel plate according to any one of claims 3 to 9, characterized in that: The quenching treatment includes any one of water quenching and brine quenching.

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