A method for improving the welding distortion of high strength alloy steel

Abstract

This invention belongs to the field of steel welding and discloses a method for improving welding deformation of high-strength alloy steel. When austenite transforms into martensite in high-strength alloy steel, it is accompanied by volume expansion. Different martensitic transformation temperatures result in different amounts of volume expansion, ultimately leading to varying degrees of welding deformation. Adding an appropriate amount of Sn element powder to the deposited metal powder can effectively change its martensitic transformation temperature. By adjusting the martensitic transformation temperature, welding deformation can be reduced, which can significantly control the degree of welding deformation in high-strength alloy steel.

Description

Technical Field

[0001] This invention belongs to the field of steel welding and relates to a method for improving welding deformation of high-strength alloy steel. Background Technology

[0002] Welding deformation is an unavoidable and one of the most difficult problems to solve in high-strength alloy steel (strength greater than 1300 MPa) during welding. Welding deformation is mainly caused by solidification shrinkage resulting from uneven heating and cooling during the welding thermal cycle. Although scholars from various countries have done a great deal of work on improving welding deformation, the methods used vary depending on the material's inherent properties and the working environment. Currently, the main methods for improving welding deformation in high-strength alloy steel include changing the welding process, reverse deformation methods, and rigid fixing methods.

[0003] Specific materials have fixed welding processes, and changing the welding process within these processes often fails to achieve the desired results. While the reverse deformation method is very effective, it is difficult to accurately predict the direction and magnitude of deformation before welding. The rigid fixing method, although simple and flexible, exhibits a certain degree of rebound after the rigid constraint is removed. Although there are many methods for controlling welding deformation, each has its limitations. Because different martensitic transformation temperatures in high-strength alloy steels lead to different volumes of expansion, resulting in varying degrees of welding deformation, designing the martensitic transformation temperature corresponding to the minimum welding deformation becomes crucial. Undoubtedly, the martensitic transformation temperature of high-strength alloy steel can be altered by appropriately changing the composition of the deposited metal. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for improving the welding deformation of high-strength alloy steel. Without reducing its mechanical properties, the method adjusts the martensitic transformation temperature of high-strength alloy steel by adding trace amounts of Sn element, thereby obtaining the Sn content corresponding to the lowest deformation amount, and thus achieving the purpose of improving the welding deformation of high-strength alloy steel.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A method for improving welding deformation of high-strength alloy steel is disclosed, wherein the filler metal raw materials are all fine powders, and the particle size range of each fine powder is 53-105 μm. The filler metal raw materials include iron powder, carbon powder, Cr powder, Ni powder, Mn powder, Mo powder, and Sn powder; the main physicochemical properties of the raw materials are as follows: Fe content > 99% by mass in iron powder, C content > 97% in carbon powder, Cr content > 99% in Cr powder, Ni content > 99% in Ni powder, Mn content > 99% in Mn powder, Mo content > 99% in Mo powder, and Sn content > 99% in Sn powder.

[0007] A method for improving welding deformation of high-strength alloy steel, the main manufacturing method of which is as follows:

[0008] (1) Determine the formula;

[0009] The components and contents of the filler metal raw material formula are as follows: C powder: 0-0.1%, Cr powder: 10-30%, Ni powder: 0-20%, Mn powder: 5-10%, Mo powder: 0-1%, and Sn powder: 0-0.5%, with the remainder being Fe powder, by mass percentage.

[0010] (2) Weigh the C, Cr, Ni, Mn, Mo, Sn and Fe powders according to the formula ratio and set aside.

[0011] (3) Place the weighed powders into a mixer and mix for 30-50 minutes until homogeneous. Then, randomly take a certain amount of the mixed material for chemical composition testing. The difference between the measured value and the formula should be accurate to two decimal places. If the difference exceeds two decimal places, mix again until the accuracy is accurate to two decimal places.

[0012] (4) Put the mixed powder into the silo for later use.

[0013] (5) Two high-strength alloy steel plates are fabricated using wire cutting. The plate dimensions are 200×100×5mm, the bevel is 45°, and the blunt edge is 1mm. The outline shape and dimensions of the plates are as follows: Figure 1 As shown:

[0014] (6) At room temperature, fiber laser automatic welding is used to butt weld two high-strength alloy steel plates. The mixed powder is delivered to the weld joint, with the powder beam and laser beam intersecting at a single point. Welding is performed simultaneously with powder delivery. The welding process is as follows: powder delivery speed is 0.54–1.50 cm / s. 3 The laser welding power is 3-5 kW, the welding speed is 150 mm / min, the defocusing amount is -4 to +4 mm, and the shielding gas flow rate is 5-25 L / min (Ar and CO2 mixture). No incomplete penetration was observed after welding.

[0015] (7) After the butt joint of the two steel plates is welded, it should be placed at room temperature for 12 to 24 hours.

[0016] According to GB / T11337-2004, flatness is measured by the cross-straightness criterion, and the obtained data is recorded.

[0017] When austenite transforms into martensite in high-strength alloy steel, it undergoes volume expansion. The amount of volume expansion varies depending on the martensitic transformation temperature, ultimately leading to different degrees of welding deformation. Adding an appropriate amount of Sn element powder to the deposited metal powder can effectively alter its martensitic transformation temperature. By adjusting the martensitic transformation temperature, welding deformation can be reduced, which can significantly control the degree of welding deformation in high-strength alloy steel. Attached Figure Description

[0018] Figure 1 It is a sample of welded plate made of high-strength alloy steel. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings.

[0020] The present invention provides a method for improving welding deformation of high-strength alloy steel, the specific process of which is as follows:

[0021] (1) Three groups of Sn-added and Sn-free fine powders were tested for comparison according to the following formula. The specific formulas are shown in the table below:

[0022]

[0023] (2) Weigh the C, Cr, Ni, Mn, Mo, Sn and Fe powders according to the formula ratio and set aside.

[0024] (3) Place the weighed elements into a mixer and mix for 30-50 minutes until homogeneous. Then, randomly take a certain amount of the mixture for chemical composition testing. The difference between the measured value and the formula should be accurate to two decimal places. If the difference exceeds two decimal places, mix again until the accuracy is accurate to two decimal places.

[0025] (4) Put the mixed material into the silo for later use.

[0026] (5) Two high-strength alloy steel plates are fabricated using wire cutting. The plate dimensions are 200×100×5mm, the bevel is 45°, and the blunt edge is 1mm. The outline shape and dimensions of the plates are shown in the figure below:

[0027] (6) At room temperature, fiber laser automatic welding is used to butt weld two high-strength alloy steel plates. Fine powder is delivered to the weld joint, with the powder beam and laser beam intersecting at a single point, and welding is performed simultaneously with powder delivery. The welding process is as follows: powder delivery speed is 0.54–1.50 cm. 3 The laser welding power was 3–5 kW, the welding speed was 150 mm / min, the defocusing amount was -4–+4 mm, the shielding gas flow rate was 5–25 L / min, and the shielding gas was a mixture of Ar and CO2. No incomplete penetration was observed after welding.

[0028] (7) After the butt joint of the two steel plates is welded, it is placed at room temperature for 12 to 24 hours.

[0029] This invention designs a method to improve the resistance of high-strength alloy steel to weld cold cracking. Welding tests were conducted on three groups of mixed metal powders containing and without Sn. Flatness was measured according to GB / T11337-2004 using the cross-straightness criterion, and the data were recorded. The results show that the flatness of the welded deformation of the three groups of Sn-containing high-strength alloy steels was 1.8, 2.0, and 1.7 cm, while the flatness of the three groups of Sn-free high-strength alloy steels was 6.4, 7.2, and 6.7 cm. This indicates that the addition of Sn can effectively improve the degree of weld deformation in high-strength alloy steels.

Claims

1. A method for improving welding deformation of high-strength alloy steel, characterized in that, Includes the following steps: (1) Determine the formula; The components and contents of the filler metal raw material formula are as follows: C powder: 0~0.1%, Cr powder: 10~30%, Ni powder: 0~20%, Mn powder: 5~10%, Mo powder: 0~1% and Sn powder: 0.2~0.5%, with the remainder being Fe powder, by mass percentage; the particle size range of each fine powder is 53~105μm; (2) Weigh the C, Cr, Ni, Mn, Mo, Sn and Fe powders according to the formula ratio and set aside; (3) Place the weighed powders into a mixer for mixing. After mixing evenly, randomly take a certain amount of the mixed material for chemical composition testing. The difference between the test result and the formula should be accurate to two decimal places. If the result exceeds two decimal places, remix the material until it is accurate to two decimal places; mix for 30-50 minutes. (4) Place the mixed powder into the silo for later use; (5) Two high-strength alloy steel plates are made by wire cutting with a bevel of 45°; (6) At room temperature, fiber laser automatic welding is used to butt weld two high-strength alloy steel plates. The mixed powder is sent to the weld seam, the powder beam and the beam intersect at one point, and welding is carried out while the powder is being sent. There is no incomplete penetration after welding. In step (6), the welding process parameters are as follows: powder feeding speed is 0.54~1.50cm. 3 / min, laser welding power is 3~5kW, welding speed is 150mm / min, defocusing amount is -4~+4mm, shielding gas flow rate is 5~25L / min; (7) After the butt joint of the two steel plates is welded, it should be placed at room temperature for 12 to 24 hours.

2. The method for improving welding deformation of high-strength alloy steel as described in claim 1, characterized in that, In step (1), the mass percentage of Fe in the iron powder is >99%, the C content in the carbon powder is >97%, the Cr content in the Cr powder is >99%, the Ni content in the Ni powder is >99%, the Mn content in the Mn powder is >99%, the Mo content in the Mo powder is >99%, and the Sn content in the Sn powder is >99%.

3. The method for improving welding deformation of high-strength alloy steel as described in claim 2, characterized in that, In step (5), the size of the board is 200×100×5mm.

4. The method for improving welding deformation of high-strength alloy steel as described in claim 3, characterized in that, The blunt edge of the sheet metal is 1mm.

5. The method for improving welding deformation of high-strength alloy steel as described in claim 4, characterized in that, The protective gas is a mixture of Ar and CO2.

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