Brass / stainless steel circumferential weld laser welding-brazing method, composite roll shaft and application

Abstract

The invention provides a brass / stainless steel circumferential weld laser welding-brazing method, a composite roll shaft and application. The method comprises the following steps that a brass roller to be welded and stainless steel journal base metal are cleaned; the brass roller is subjected to surface treatment, and a micro capillary channel is prepared; the brass roller and the stainless steel journal workpiece are sequentially placed into a welding tool to be positioned and clamped; and welding is started, a copper-nickel-manganese-silicon quaternary solid welding wire is used as filling metal, and laser melt-brazing welding is conducted on the brass / stainless steel circumferential weld. According to the brass / stainless steel circumferential weld laser melt-brazing method, the composite roll shaft and the application, continuous distribution of intermetallic compounds on a brass / stainless steel interface is eliminated, the porosity in a connector is reduced, and high-strength laser melt-brazing connection of brass / stainless steel heterogeneous materials is achieved; the prepared composite roll shaft is far better than a stainless steel roll shaft in thermal conductivity and temperature control performance, is applied to preparation of a wide-width roller, and realizes high-quality manufacturing of ultrathin wide-width materials.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more specifically, to a laser brazing method for brass / stainless steel circumferential welds and a brass / stainless steel composite roller shaft and its application. Background Technology

[0002] For the manufacturing of ultra-thin, wide-width materials such as meltblown nonwoven fabrics, calendered films, and chemical fibers, rollers are an indispensable core component of the manufacturing equipment. A roller consists of a working area roller shaft and a supporting journal. In engineering, the roller shaft is expected to have good thermal conductivity to ensure temperature uniformity and dimensional accuracy in the working area; the journal is expected to have sufficient rigidity to ensure support. Traditional wide-width rollers are usually composed of stainless steel mirror-finish roller shafts and stainless steel shaft ends. However, the inherent thermal conductivity of stainless steel makes it difficult to achieve uniform temperature quickly, thus limiting the application of stainless steel rollers in certain scenarios. Brass, mainly composed of copper and zinc, has far superior thermal conductivity and temperature control compared to stainless steel. In recent years, composite roller shafts made by brazing brass roller shafts and stainless steel journals have gradually begun to be used.

[0003] Brass is an alloy composed of copper and zinc. Because zinc, a constituent element of brass, has a very high saturated vapor pressure, atmospheric induction brazing is currently the primary method for joining dissimilar materials such as brass and stainless steel. This method requires the use of corrosive flux to remove the oxide film from the surfaces of both brass and stainless steel during the brazing process. Therefore, in addition to the common problem of low strength due to continuous compound formation at the interface between dissimilar materials, it also presents challenges such as difficulty in cleaning the flux after welding, discoloration of the workpiece surface, and poor joint strength due to flux inclusions.

[0004] Laser brazing, as a novel welding technology, can remove oxide films and achieve mutual wetting of the materials by designing appropriate filler wire compositions based on the materials being joined. This method eliminates the need for flux, thus avoiding the problems associated with induction brazing of brass / stainless steel, such as post-weld flux cleaning, workpiece surface discoloration, and flux inclusions. In summary, using filler wires with specific compositions and employing specific methods to break the continuous compound layer at the brass / stainless steel interface to achieve high-strength laser brazing of dissimilar materials has broad application prospects.

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

[0006] The purpose of this invention is to address the shortcomings of existing brass / stainless steel dissimilar material welding techniques, which result in poor weld joint strength. This invention provides a laser brazing method for brass / stainless steel circumferential welds, a composite roller shaft, and its application. This method eliminates the continuous distribution of intermetallic compounds at the brass / stainless steel interface and reduces the porosity inside the joint, thereby improving the joint strength of the brass / stainless steel butt circumferential weld and achieving high-strength laser brazing connection of dissimilar materials. The prepared brass / stainless steel composite roller shaft exhibits significantly better thermal conductivity and temperature control than stainless steel roller shafts, and can be applied to the manufacture of wide-width rollers, enabling high-quality manufacturing of ultra-thin, wide-width materials.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A method for laser brazing of brass / stainless steel circumferential weld seams includes the following steps: Step S1: Clean the brass roller 2 and the stainless steel journal 3 base material to be welded; Step S2: Perform surface treatment on the brass roller 2 to prepare micro capillary channels; Step S3: Place the brass roller 2 and the stainless steel journal 3 workpiece into the welding fixture for positioning and clamping in sequence; Step S4: Start welding. Use copper-nickel-manganese-silicon quaternary solid welding wire as filler metal to perform laser brazing on the brass / stainless steel circumferential weld.

[0008] Further, in step S2, a wheel-shaped rolling die 7 with a textured surface is used for mechanical rolling to prepare micron-scale microcapillary channels.

[0009] Furthermore, in step S2, the brass roller 2 undergoes surface preparation of micro-capillary channels followed by beveling.

[0010] Furthermore, in step S2, during the rolling process, the angle α between the surface texture direction of the wheel-shaped rolling die 7 and the axis of the brass roller 2 is 10°~30°, and the spacing L between adjacent texture channels is 1~3mm.

[0011] Furthermore, the diameter d of the wheel-shaped roller pressing die 7 is 15~20mm, the thickness S is 10~15mm, and the rolling depth h is 0.1±0.05mm.

[0012] Furthermore, the width of the microcapillary channel is 50~150μm.

[0013] Furthermore, the formula for calculating the ratio of the surface area A0 after fabrication of microcapillary channels to the surface area A1 before fabrication is as follows: , Wherein, D is the inner diameter of the brass roller (2), S is the thickness of the wheel-shaped roller pressing die (7), h is the rolling depth of the wheel-shaped roller pressing die (7), L is the spacing between adjacent channels of the mesh, and α is the angle between the mesh direction and the axis of the brass roller (2). The microcapillary channel structure design satisfies: The ratio is 1.16 to 1.47.

[0014] Furthermore, the cross-section of the microcapillary channels formed by the roller pressing is an equilateral triangle.

[0015] Furthermore, in step S2, the micro-capillary channel roll forming and beveling angle processing are completed by using a two-stage reversal clamping method.

[0016] Furthermore, in step S2, the bevel angle is 30°~45° and the bevel thickness is 2~4mm.

[0017] Furthermore, in step S3, the brass roller 2 and the stainless steel journal 3 are clamped and secured in the form of a butt joint, and the bevel gap is controlled to 1±0.5mm during the securing process.

[0018] Furthermore, the composition of the copper-nickel-manganese-silicon quaternary solid welding wire used in step S4 includes: copper 82.8~87.2wt%, nickel 9~11wt%, manganese 3~5wt%, and silicon 0.8~1.2wt%.

[0019] Furthermore, the laser welding process parameters used in step S4 are as follows: laser power 1200~3000W, defocusing amount -1~+1mm, welding angle 30~45°, wire spacing 0~3mm, wire offset to the stainless steel side 0.5~1.5mm, and wire feeding speed 7~12m / min.

[0020] Furthermore, in step S4 laser welding, the workpiece rotates at a constant speed of 3~8 r / min, while the laser source remains in a fixed position.

[0021] Furthermore, in step S4 laser welding, the shielding gas flow rate is 15~25L / min.

[0022] Furthermore, the number of filler welds in step S4 laser welding is 1 to 5.

[0023] The brass / stainless steel composite roller shaft prepared by the above-mentioned brass / stainless steel circumferential weld laser brazing method includes a brass roller 2 and a stainless steel journal 3. The inner diameter of the brass roller 2 is 150~300mm and the wall thickness is 10~20mm. The outer diameter of the stainless steel journal 3 is 147~299mm.

[0024] The above-mentioned laser brazing method for brass / stainless steel circumferential welds and the application of the above-mentioned brass / stainless steel composite roller shaft in the preparation of wide rollers.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides a laser fusion brazing method for brass / stainless steel circumferential welds. By designing and preparing microscale regularly distributed capillary channels and copper-nickel-manganese-silicon quaternary filler wires on the bevel surface of the brass roller, the continuous distribution of intermetallic compounds at the brass / stainless steel interface is eliminated, the porosity inside the joint is reduced, and the joint strength of the brass / stainless steel butt circumferential weld is improved, thus realizing a high-strength laser fusion brazing connection of dissimilar materials such as brass and stainless steel.

[0026] 2. The present invention provides a laser fusion brazing method for brass / stainless steel circumferential welds, which focuses on two key aspects: interface physical structure design and metallurgical reaction. A mechanical rolling method is used to prepare micro-scale, regularly distributed microcapillary channels on the bevel surface of the brass roller to be welded, thereby disrupting the continuous layered intermetallic compound reaction at the straight brazing interface of brass / stainless steel. A specific composition of copper-nickel-manganese-silicon quaternary solid welding wire is used to achieve the removal of oxide films on the surfaces of dissimilar materials and mutual wetting.

[0027] 3. The laser fusion brazing method for brass / stainless steel circumferential welds of the present invention has advantages over induction brazing of brass / stainless steel, such as no need to add flux, no discoloration of the workpiece surface, and no flux inclusions.

[0028] 4. The brass / stainless steel composite roller shaft prepared by the brazing method of the present invention has far superior thermal conductivity and temperature control compared to stainless steel roller shafts. When applied to the preparation of wide-width rollers, it can achieve high-quality manufacturing of ultra-thin wide-width materials such as meltblown nonwoven fabrics, calendered films, and chemical fiber industries. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the overall brass / stainless steel circumferential weld laser brazing system of the present invention; Figure 2 This is a schematic diagram illustrating the preparation process of the microtexture morphology (microcapillary channels) on the surface of the brass bevel to be welded according to the present invention; Figure 3 This describes the surface morphology of the wheel-shaped roller pressing die with a textured surface according to the present invention. Figure 4The unfolded pattern and dimensions of the micro capillary channel of the present invention; Figure 5 This is a schematic diagram of a brass roller workpiece with micro capillary channels on its surface, according to the present invention. Figure 6 This is a schematic diagram of a brass roller workpiece with micro-capillary channels on its surface, as described in this invention. Figure 5 Enlarged view of a portion of point A in the middle; Figure 7 This is a schematic cross-sectional view of a brass roller workpiece after one end of the present invention has undergone surface rolling and beveling (the other end is to be processed). Figure 8 For the present invention Figure 7 Enlarged view of a section at point B in the middle; Figure 9 Metallographic micrograph of the brass / stainless steel circumferential weld joint prepared in Example 1; Figure 10 Metallographic micrograph of the brass / stainless steel circumferential weld joint prepared in Example 2; Figure 11 Metallographic micrograph of the brass / stainless steel circumferential weld joint prepared in Comparative Example 1. Figure 12 Metallographic micrograph of the brass / stainless steel circumferential weld joint prepared in Comparative Example 2.

[0031] Explanation of reference numerals in the attached drawings: 1-T-type positioner; 2-Brass roller; 3-Stainless steel journal; 4-Side shaft wire feed tube; 5-Laser welding gun; 6-Three-jaw chuck; 7-Wheel-shaped roller pressing die. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0033] A method for laser brazing of brass / stainless steel circumferential weld seams includes the following steps: Step S1: Clean the brass roller 2 and the stainless steel journal 3 base material to be welded; Step S2: Perform surface treatment on the brass roller 2 to be welded, prepare micro capillary channels and perform beveling angle processing; Step S3: The workpieces to be welded are placed into the welding fixture in sequence and positioned and clamped. Step S4: Start welding. Use copper-nickel-manganese-silicon quaternary solid welding wire as filler metal to perform laser brazing on the brass / stainless steel circumferential weld.

[0034] Preferably, before performing the surface treatment of the brass roller 2 in step S2, step S1 involves cleaning the surfaces of the brass roller 2 to be welded and the stainless steel journal 3 base material respectively.

[0035] Preferably, the surface cleaning method in step S1 is as follows: at room temperature, the brass roller 2 workpiece is immersed in a 5% dilute sulfuric acid cleaning bath for 15 seconds, then taken out and immersed in a 15% citric acid bath for 3-5 minutes, rinsed with anhydrous ethanol and dried at low temperature; the stainless steel journal 3 base material workpiece is cleaned by wiping with acetone or rinsing with alcohol at room temperature and then air-drying naturally to remove oil and rust from the machined surface.

[0036] Preferably, in step S2, a wheel-shaped roller pressing die 7 with a textured surface is used for mechanical rolling to prepare micro-capillary channels with a width of 50~150μm (including but not limited to 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm). The rolling process is as follows: rolling is performed along the thickness direction of the bevel surface of the brass roller 2 to prepare circumferentially distributed mesh-like micro-capillary channels. The morphology of the micro-capillary channels is controlled by adjusting the mesh shape on the surface of the wheel-shaped roller pressing die 7 and the rolling depth.

[0037] This invention relates to a laser brazing method for brass / stainless steel circumferential welds. The strength of the brazed joint is controlled from two perspectives: interface physical structure design and metallurgical reaction control. Micro-capillary channels with a regular micron-scale distribution are prepared on the bevel surface of the brass roller 2 to be welded using a mechanical rolling method. A copper-nickel-manganese-silicon quaternary solid welding wire of a specific composition is used as filler metal, achieving the removal of oxide films on the surfaces of the dissimilar materials and mutual wetting. During welding, the brass roller 2 base material and the filler welding wire melt together under the action of the laser heat source and fill the bevel and the micro-capillary channels on the bevel surface. During circumferential weld welding, a T-type positioner 1 drives the workpiece to rotate at a uniform speed in the flat welding position, while the laser source remains in a fixed position to ensure stable welding. The overall tooling system is as follows: Figure 1 As shown.

[0038] Preferably, in step S2, during the rolling process, the angle α between the surface texture direction of the wheel-shaped rolling die 7 and the axis of the brass roller 2 is 10°~30° (including but not limited to 10°, 15°, 20°, 25°, 30°), the diameter d of the wheel-shaped rolling die 7 is 15~20mm (including but not limited to 15mm, 16mm, 17mm, 18mm, 19mm, 20mm), the thickness S is 10~15mm (including but not limited to 10mm, 11mm, 12mm, 13mm, 14mm, 15mm), and the rolling depth h is 0.1±0.05mm (50~150μm), including but not limited to 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm.

[0039] Preferably, the formula for calculating the ratio of the surface area A0 after the micro-capillary channels are fabricated to the surface area A1 before fabrication is as follows: , Wherein, D is the inner diameter of the brass roller (2), S is the thickness of the wheel-shaped roller pressing die (7), h is the rolling depth of the wheel-shaped roller pressing die (7), L is the spacing between adjacent channels of the mesh, and α is the angle between the mesh direction and the axis of the brass roller (2). The microcapillary channel structure design satisfies: The ratio is 1.16 to 1.47, including but not limited to 1.16, 1.2, 1.25, 1.3, 1.35, 1.4, and 1.47.

[0040] Preferably, the cross-section of the microcapillary channel formed by the roller pressing is an equilateral triangle.

[0041] Preferably, in step S2, the micro-capillary channel roll forming and beveling angle processing are completed by a two-stage reversal clamping method.

[0042] like Figure 2 As shown, the first step is to fix one end of the brass roller 2 on the horizontal lathe using the three-jaw chuck 6, and use the center rest to support and fix the other end of the brass roller 2 on its outer cylindrical surface; use a dial indicator to make corrections near the three-jaw chuck 6 and the center rest to ensure that the coaxiality error between the workpiece axis of the brass roller 2 and the lathe spindle axis is less than 0.05mm and the outer cylindrical runout is less than 0.1mm.

[0043] The second step adopts Figure 3The textured wheel-shaped pressing die 7 shown is aligned with the end face of the brass roller 2 and kept parallel to its axis in the height direction. Then, the brass roller 2 is rotated in the reverse direction, and the tool holder drives the wheel-shaped pressing die 7 to feed in the height direction and move in the forward direction, rolling out micro capillary channels with a depth of 50~150μm on the inner surface of the brass roller 2. Figure 4 The diagram shows the planar unfolding of the surface texture of the wheel-shaped roller pressing die 7. The spacing L between adjacent channels is 1~3mm. During the rolling process, the angle between the surface texture and the axis of symmetry on one side is 10°~30°, and the total angle between two adjacent channels is 20°~60°.

[0044] The third step involves maintaining the clamping position, switching to a reverse internal bore cutting tool, and using a 55° rhomboid insert to machine the welding bevel. The welding bevel angle here is 30°~45° (including but not limited to 30°, 31°, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°, 43°, 44°, 45°), and the bevel thickness is 2~4mm (including but not limited to 2mm, 3mm, 4mm). A schematic diagram of the final brass roller after roll forming is shown below. Figure 5 and Figure 7 As shown, Figure 6 and Figure 8 These are enlarged schematic diagrams of the surface of the brass roller 2 and the transverse cross-section of the bevel surface, respectively.

[0045] The fourth step involves reversing the clamping of the brass roller 2, and repeating steps one through three to complete the micro-capillary channel roll forming and beveling angle processing at the other end of the brass roller 2.

[0046] Preferably, after the surface treatment of the brass roller 2 in step S2, the brass roller 2 with micro capillary channels and the stainless steel journal 3 are clamped and fixed in the form of a butt joint in step S3, and the bevel gap is controlled to 1±0.5mm during the fixing.

[0047] Preferably, in step S4, a copper-nickel-manganese-silicon quaternary solid welding wire is used for welding. Key process parameters such as laser power, defocusing amount, welding angle, wire spacing, wire offset, and wire feeding speed are adjusted to perform laser brazing welding on the brass / stainless steel butt ring weld.

[0048] Preferably, the composition of the copper-nickel-manganese-silicon quaternary solid welding wire used in step S4 includes: copper 82.8~87.2wt%, nickel 9~11wt%, manganese 3~5wt%, and silicon 0.8~1.2wt%.

[0049] Preferably, the laser welding process parameters used in step S4 are: laser power 1200~3000W (including but not limited to 1200W, 1400W, 1600W, 1800W, 2000W, 2200W, 2400W, 2600W, 2800W, 3000W), defocusing amount -1~+1mm (including but not limited to -1.0mm, -0.9mm, -0.8mm, -0.7mm, -0.6mm, -0.5mm, -0.4mm, -0.0mm). Welding wire thicknesses are available in various sizes: -0.3mm, -0.2mm, -0.1mm, 0.0mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, and 1.0mm. Welding angles range from 30° to 45° (including but not limited to 30°, 35°, 40°, and 45°). The wire spacing is 0 to 3mm (including but not limited to 0mm, 1mm, 2mm, and 3mm), and the wire offset towards the stainless steel side is 0.5 to 1.5mm. mm (including but not limited to 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm), the wire feeding speed of the off-axis wire feeding tube 4 (including quaternary solid welding wire) is 7~12m / min (including but not limited to 7m / min, 8m / min, 9m / min, 10m / min, 11m / min, 12m / min), and the T-type positioner 1 drives the workpiece to rotate at a uniform speed. Rotation speed 3~8 r / min (including but not limited to 3 r / min, 4 r / min, 5 r / min, 6 r / min, 7 r / min, 8 r / min), protective gas flow rate 15~25 L / min (including but not limited to 15 L / min, 16 L / min, 17 L / min, 18 L / min, 19 L / min, 20 L / min, 21 L / min, 22 L / min, 23 L / min, 24 L / min, 25 L / min).

[0050] Preferably, the protective gas is at least one of argon and helium.

[0051] Preferably, after the point fixing clamping is completed in step S3, the welding trajectory is taught in step S4 before welding. The laser welding gun 5 is moved to the starting position of the weld, and the T-type positioner 1 drives the workpiece to rotate at a uniform speed. The offset between the end of the filler wire and the center of the bevel is adjusted using a steel ruler to ensure that the wire is biased towards the stainless steel side throughout the entire weld circumference, with an offset of 1±0.5mm. Multiple no-load runs are repeated to verify the trajectory consistency.

[0052] Preferably, the number of filler welds in step S4 laser welding is 1 to 5.

[0053] The brass / stainless steel composite roller shaft prepared by the above-mentioned laser brazing method for brass / stainless steel circumferential weld seam.

[0054] Preferably, the composite roller shaft includes a brass roller 2 and a stainless steel journal 3. The inner diameter of the brass roller 2 is 150~300mm (including but not limited to 150mm, 180mm, 210mm, 240mm, 270mm, 300mm), and the wall thickness is 10~20mm (including but not limited to 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm). The outer diameter of the stainless steel journal 3 is 147~299mm (including but not limited to 147mm, 150mm, 180mm, 210mm, 240mm, 270mm, 299mm). In some specific embodiments, the brass roller has an inner diameter of 152mm and a wall thickness of 10mm, and the stainless steel journal has an outer diameter of 150mm.

[0055] The above-mentioned laser brazing method for brass / stainless steel circumferential welds and the application of the above-mentioned brass / stainless steel composite roller shaft in the preparation of wide rollers.

[0056] Example 1 A method for laser brazing of brass / stainless steel circumferential weld seams includes the following steps: Step A: Immerse the H62 brass roller 2 with an inner diameter of 152mm and a wall thickness of 10mm in a 5% dilute sulfuric acid cleaning bath for 15 seconds at room temperature. Then, remove it and immerse it in a 15% citric acid solution for 3-5 minutes. Rinse with anhydrous ethanol and dry at low temperature. Rinse the area to be welded of the solid SUS304 stainless steel journal 3 with an outer diameter of 150mm with anhydrous ethanol and air dry naturally to remove surface oil and rust.

[0057] Step B: Fix the brass roller 2 onto the lathe using a three-jaw chuck 6. Use a wheel-shaped roller pressing die 7 with a diameter of 15mm, a thickness of 10mm, and a surface mesh pattern at a 20° angle to the center line to roll the brass bevel surface to prepare a micro capillary channel with a depth of 0.1mm and process a welding bevel with an angle of 30°.

[0058] Step C: Clamp and secure the brass roller 2 and the stainless steel journal 3 workpiece in sequence. When securing, the bevel gap should be controlled to 1±0.5mm.

[0059] Step D: Move the laser welding gun 5 to the weld start position. The T-positioner 1 drives the workpiece to rotate at a uniform speed. Use a steel ruler to adjust the offset between the end of the filler wire and the center of the bevel, ensuring that the wire is biased towards the stainless steel side throughout the entire weld circumference, with an offset of 1±0.5mm. Repeat the test multiple times to ensure trajectory consistency.

[0060] Step E: Adjust the laser brazing process parameters and start welding. Adjust the laser power to 1500W, defocusing amount to 0mm, welding angle to 45°, wire spacing to 2mm, wire feed speed to 8m / min, T-positioner speed to 5r / min, and side protection pure Ar gas flow rate to 20L / min. Use a quaternary solid welding wire containing 87.2wt% copper, 9wt% nickel, 3wt% manganese, and 0.8wt% silicon as filler metal, and fill in a single layer and pass until welding is completed.

[0061] The brass / stainless steel butt weld joints obtained using the above welding process exhibit good formation, with no obvious undercut or porosity defects. Interface observation results are as follows: Figure 9 As shown, the brittle phase at the brass / stainless steel interface was found to be relatively uniform in thickness along the thickness direction, exhibiting a bent and discontinuous distribution. The shear strength of the joint was tested according to GB / T 11363-2022, and the average joint strength was 337 MPa.

[0062] Example 2 A method for laser brazing of brass / stainless steel circumferential weld seams includes the following steps: Step A: Immerse the H62 brass roller 2 with an inner diameter of 300mm and a wall thickness of 20mm in a 5% dilute sulfuric acid cleaning bath for 15 seconds at room temperature. Then, remove it and immerse it in a 15% citric acid solution for 3-5 minutes. Rinse with anhydrous ethanol and dry at low temperature. Rinse the area to be welded of the solid SUS304 stainless steel journal 3 with an outer diameter of 298mm with anhydrous ethanol and air dry naturally to remove surface oil and rust.

[0063] Step B: Fix the brass roller 2 onto the lathe using a three-jaw chuck 6. Use a wheel-shaped roller pressing die 7 with a diameter of 15mm, a thickness of 10mm, and a surface mesh pattern at a 20° angle to the center line to roll the brass bevel surface to prepare a micro capillary channel with a depth of 0.1mm and process a welding bevel with an angle of 45°.

[0064] Step C: Clamp and secure the brass roller 2 and the stainless steel journal 3 workpiece in sequence. When securing, the bevel gap should be controlled to 1±0.5mm.

[0065] Step D: Move the laser welding gun 5 to the weld start position. The T-positioner 1 drives the workpiece to rotate at a uniform speed. Use a steel ruler to adjust the offset between the end of the filler wire and the center of the bevel, ensuring that the wire is biased towards the stainless steel side throughout the entire weld circumference, with an offset of 1±0.5mm. Repeat the test multiple times to ensure trajectory consistency.

[0066] Step E: Adjust the laser brazing process parameters and start welding. Adjust the laser power to 3000W, defocusing amount to 0mm, welding angle to 45°, wire spacing to 2mm, wire feed speed to 8m / min, T-positioner speed to 5r / min, and side protection pure Ar gas flow rate to 20L / min. Use a quaternary solid welding wire containing 82.8wt% copper, 11wt% nickel, 5wt% manganese, and 1.2wt% silicon as filler metal, and perform 3 layers and 5 passes of filler welding until welding is completed.

[0067] The brass / stainless steel butt weld joints obtained using the above welding process exhibit good formation, with no obvious undercut or porosity defects. Interface observation results are as follows: Figure 10 As shown, the brittle phase at the brass / stainless steel interface is relatively uniform in thickness along the thickness direction and is distributed in a bent and discontinuous manner. The shear strength of the joint was tested according to GB / T 11363-2022, and the average joint strength was 329 MPa.

[0068] Comparative Example 1 Compared with Example 1, the cleaning process and brazing method and parameters of the base material in this comparative example are the same. The difference is that the brass bevel surface was not roll-pressed to create micron-scale capillary channels. The interface was observed, and the results are as follows: Figure 11 As shown, observations revealed the formation of a flatly distributed brittle intermetallic compound phase at the brass / stainless steel interface, along with localized microcracks. Shear strength tests were conducted on the joint, and the average joint strength was 294 MPa.

[0069] Comparative Example 2 Compared with Example 1, this comparative example maintains the same cleaning process for the base material, the micron-sized capillary channels on the brass bevel surface, and the brazing method and parameters. The difference lies in the use of copper-silicon binary welding wire for the deposited metal. The interface was observed, and the results are as follows: Figure 12 As shown, observations revealed the formation of a flatly distributed brittle intermetallic compound phase at the brass / stainless steel interface, with localized microcracks. Shear strength tests were performed on the joint, and the average strength was 263 MPa.

[0070] While the embodiments disclosed in this invention are as described above, their content is merely for the purpose of facilitating understanding of the technical solutions of this invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes to the form and details of the implementation without departing from the core technical solutions disclosed in this invention; however, the scope of protection defined by this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for laser brazing of brass / stainless steel circumferential welds, characterized in that, Includes the following steps: Step S1: Clean the brass roller (2) to be welded and the stainless steel journal (3) base material; Step S2: The brass roller (2) is surface treated to prepare micro capillary channels; Step S3: Place the brass roller (2) and the stainless steel journal (3) workpiece into the welding fixture for positioning and clamping in sequence; Step S4: Start welding. Use copper-nickel-manganese-silicon quaternary solid welding wire as filler metal to perform laser brazing on the brass / stainless steel circumferential weld.

2. The laser brazing method for brass / stainless steel circumferential welds according to claim 1, characterized in that, Step S2 uses a wheel-shaped rolling die (7) with a textured surface to perform mechanical rolling to prepare micron-scale micro capillary channels.

3. The laser brazing method for brass / stainless steel circumferential welds according to claim 1, characterized in that, After preparing micro-capillary channels on the surface of the brass roller (2) in step S2, the bevel angle is processed.

4. The laser brazing method for brass / stainless steel circumferential welds according to claim 2, characterized in that, Includes at least one of the following technical features: (1) In step S2, the angle α between the surface texture direction of the wheel-shaped roller pressing die (7) and the axis of the brass roller (2) is 10°~30°, and the spacing L between adjacent texture channels is 1~3mm; (2) The diameter d of the wheel-shaped roller pressing die (7) is 15~20mm, the thickness S is 10~15mm, and the pressing depth h is 0.1±0.05mm; (3) The width of the micro capillary channel is 50~150μm; (4) The formula for calculating the ratio of the surface area A0 after the fabrication of micro capillary channels to the surface area A1 before fabrication is as follows: ， Wherein, D is the inner diameter of the brass roller (2), S is the thickness of the wheel-shaped roller pressing die (7), h is the rolling depth of the wheel-shaped roller pressing die (7), L is the spacing between adjacent channels of the mesh, and α is the angle between the mesh direction and the axis of the brass roller (2). The microcapillary channel structure design satisfies: The ratio is 1.16~1.47; (5) The cross-section of the micro capillary channel formed by roller pressing is an equilateral triangle.

5. The laser brazing method for brass / stainless steel circumferential welds according to claim 3, characterized in that, Includes at least one of the following technical features: (1) In step S2, the micro capillary channel roll forming and beveling angle processing are completed by two reversing clamping methods; (2) In step S2, the bevel angle is 30°~45° and the bevel thickness is 2~4mm.

6. The laser brazing method for brass / stainless steel circumferential welds according to claim 3, characterized in that, In step S3, the brass roller (2) and the stainless steel journal (3) are clamped and fixed in the form of a butt joint, and the bevel gap is controlled to 1±0.5mm during the fixing.

7. The laser brazing method for brass / stainless steel circumferential welds according to claim 1, characterized in that, The composition of the copper-nickel-manganese-silicon quaternary solid welding wire used in step S4 includes: copper 82.8~87.2wt%, nickel 9~11wt%, manganese 3~5wt%, and silicon 0.8~1.2wt%.

8. The laser brazing method for brass / stainless steel circumferential welds according to claim 1, characterized in that, Includes at least one of the following technical features: (1) The laser welding process parameters used in step S4 are: laser power 1200~3000W, defocusing amount -1~+1mm, welding angle 30~45°, wire spacing 0~3mm, wire offset to stainless steel side 0.5~1.5mm, and wire feeding speed 7~12m / min. (2) In step S4 laser welding, the workpiece rotates at a constant speed of 3~8 r / min, and the laser source is kept in a fixed position; (3) In step S4 laser welding, the shielding gas flow rate is 15~25L / min; (4) The number of filler welds in step S4 laser welding is 1 to 5.

9. The brass / stainless steel composite roller shaft prepared by the laser brazing method for brass / stainless steel circumferential weld as described in any one of claims 1 to 8, characterized in that, The composite roller includes a brass roller (2) and a stainless steel journal (3). The inner diameter of the brass roller (2) is 150~300mm and the wall thickness is 10~20mm. The outer diameter of the stainless steel journal (3) is 147~299mm.

10. The method for laser brazing of brass / stainless steel circumferential welds as described in any one of claims 1 to 8, and the application of the brass / stainless steel composite roller shaft as described in claim 9 in the preparation of wide-width rollers.

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