Wear-resistant layer material of angle steel roller and strengthening process of angle steel roller

Abstract

The application discloses a wear-resistant layer material of an angle steel press roller, which is an iron-based alloy powder, and chemical components and mass percentages are as follows: 13-19% of Cr, 0.8-2.1% of Ni, 0.5-1.5% of Mo, 0.8-2% of B, 1.0-1.8% of Si, <0.5% of C, <1.0% of Mn, and the balance of Fe. Meanwhile, the application discloses a reinforcing process of the angle steel press roller, which comprises the following steps: ① machining; ② pre-inspection; ③ laser cladding: iron-based alloy powder is cladded on the surface of the press roller, and chemical components and mass percentages are as follows: 13-19% of Cr,0.8-2.1% of Ni, 0.5-1.5 % of Mo, 0.8-2% of B, 1.0-1 8% of Si, <0.5% of C, <1.0% ofMn, and the balance of Fe; ④ turning; and ⑤ post-inspection. The angle steel press roller has excellent wear resistance, high-temperature resistance and impact resistance, and the service life of the angle steel press roller is increased by about 2-3 times compared with that of a traditional hardfacing or cast angle steel press roller, so that the angle steel press roller does not need to be frequently replaced and the use cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of material surface modification, and in particular to a wear-resistant layer material and strengthening process for an angle steel pressure roller. Background Technology

[0002] In recent years, my country's steel industry has developed rapidly, with a surge in the output of various steel profiles such as angle steel, I-beams, and H-beams. Angle steel, a type of steel profile, is widely used in various building and engineering structures, such as roof beams, bridges, transmission towers, lifting and transport machinery, ships, industrial furnaces, reaction towers, container racks, and warehouse shelves. With the increase in angle steel production, the consumption of pressure rollers in angle steel rolling has also increased rapidly. The huge cost of these rollers severely restricts the development of steel mills. Therefore, extending the service life of pressure rollers in angle steel rolling has become an urgent problem for steel profile manufacturers.

[0003] During the rolling process, the temperature of angle steel billets reaches as high as 800℃-900℃, meaning the surface temperature of the pressure rolls is extremely high during operation. Simultaneously, the angle steel moves at high speeds, reaching up to 15m / s, and the steel is generally heavy, subjecting the pressure rolls to immense impact and friction. Accordingly, angle steel rolling pressure rolls need to possess excellent high-temperature resistance, wear resistance, and impact resistance. Furthermore, during rolling, the high-temperature rolled piece experiences significant overload pressure through the die. Under the influence of factors such as heat, rolling force, alternating stress, roll stress, and water cooling, the pressure rolls gradually develop oxidative micro-fatigue cracks. Continued rolling leads to crack indentation on the surface of the rolled piece; therefore, the pressure rolls must also possess fatigue resistance.

[0004] Because angle steel pressure rollers operate under extremely harsh conditions, they are prone to cracking and even peeling. Currently, the main methods for extending their service life include integral casting and welding a wear-resistant layer. Integral casting involves adding high-alloy materials during the roller casting process, resulting in higher costs. Welding, on the other hand, involves significant heat input, large deformation, and a high dilution rate, requiring multiple layers to mitigate the impact. Furthermore, the preheating before welding also results in substantial heat input, leading to coarse grains in the wear-resistant layer and reduced mechanical properties. Therefore, angle steel pressure rollers obtained using these methods are generally unsuitable for angle steel production lines, have short service lives, and are costly to operate. Summary of the Invention

[0005] The problem this invention aims to solve is to provide a wear-resistant layer material for angle steel rollers and a strengthening process for angle steel rollers. The angle steel rollers of this invention possess excellent wear resistance, high-temperature resistance, and impact resistance. Their service life is increased by approximately 2 to 3 times compared to traditional welded or cast angle steel rollers, eliminating the need for frequent replacements and reducing operating costs.

[0006] The wear-resistant layer material of the angle steel pressure roller of the present invention is an iron-based alloy powder with the following chemical composition and mass percentage: 13-19% Cr, 0.8-2.1% Ni, 0.5-1.5% Mo, 0.8-2% B, 1.0-1.8% Si, <0.5% C, <1.0% Mn, and the balance being Fe.

[0007] The preferred chemical composition and mass percentage of the iron-based alloy powder are as follows: 15.8-19% Cr, 1.5-1.9% Ni, 0.9-1.3% Mo, 1.0-1.7% B, 1.0-1.5% Si, <0.2% C, <0.7% Mn, with the balance being Fe.

[0008] The iron-based alloy powder is produced by gas atomization powder preparation, and the alloy particle size is 53μm-150μm.

[0009] The strengthening process of the angle steel pressure roller of the present invention includes the following steps:

[0010] ① Machining: Machin the original blank according to the drawings, wherein the outer circle of the pressure roller is turned to be 2mm smaller than the final size of the roller;

[0011] ② Pre-inspection: Perform colorimetric and ultrasonic testing on the machined conveyor rollers to ensure that the rollers are free of defects such as cracks, air holes, and inclusions;

[0012] ③ Laser cladding: Iron-based alloy powder is clad onto the surface of the pressure roller. The chemical composition and mass percentage are: 13-19% Cr, 0.8-2.1% Ni, 0.5-1.5% Mo, 0.8-2% B, 1.0-1.8% Si, <0.5% C, <1.0% Mn, with the balance being Fe.

[0013] ④ Turning: Finish turning the roller surface to the final required dimensions and tolerances;

[0014] ⑤ Post-flaw inspection: After precision machining, the pressure roller is subjected to colorimetric and ultrasonic flaw inspection to ensure that the pressure roller is free of defects such as cracks and air holes.

[0015] In step ③, laser cladding, the pressure roller is preheated to 100-150℃ before cladding. Preheating the pressure roller reduces the risk of cracking of the cladding layer, while also avoiding poor cladding formation due to excessive temperature and preventing the appearance of pores.

[0016] Among them, step ③ laser cladding: the cladding process parameters are: circular spot size φ5mm, laser power 3~4kW, scanning speed 12~18mm / s, powder feeding rate 40~65g / min, and overlap rate 40%~60%.

[0017] In step ③, laser cladding, the thickness of the alloy powder cladding layer is 1.7–1.9 mm.

[0018] The principle and effects of the wear-resistant layer material of the angle steel pressure roller of this invention are as follows: I. The iron-based alloy is an iron-based self-fluxing alloy: 0.8-2% B and 1.0-1.8% Si mainly lower the alloy melting point, forming a low-melting-point eutectic, and simultaneously forming hard phases such as CrB, thus improving the alloy's hardness and wear resistance to a certain extent; 13-19% Cr can improve the alloy's corrosion resistance, and a certain amount of Cr element forms a Cr2O3 protective layer on the cladding layer surface, improving the alloy's oxidation resistance and adapting to the high working temperature of the angle steel pressure roller; 0.5-1.5% Mo improves the alloy's wear resistance. At the same time, Mo has a larger atomic radius, resulting in less lattice distortion when forming a solid solution. First, the high carbon content significantly strengthens the γ matrix, thereby significantly improving the high-temperature strength of the alloy. Second, Cr can refine the grains, and Ni can promote microstructure refinement. The phases of steel containing Cr and Ni are Fe-Cr-Ni solid solution, FeC, and Cr3C2, which can refine the grains and thus improve impact resistance. At the same time, the hardness is increased, and the impact resistance is also improved. Si can improve the elastic limit, yield strength, and yield ratio (σs / σb) of steel, as well as fatigue strength and fatigue ratio (σ-1 / σb), thereby improving fatigue resistance. Third, the alloy has extremely low carbon content, which prevents intergranular corrosion and improves mechanical strength. After being subjected to impact, the surface coating and the substrate are less prone to cracking and coating peeling.

[0019] As can be seen from the above, compared with conventionally used iron-based materials, the alloy material used in this invention possesses excellent comprehensive properties such as wear resistance, high temperature resistance, impact resistance, resistance to thermal fatigue, and corrosion resistance. Furthermore, the individual and coupled effects of multiple elements in the material result in good processing performance, significantly reducing the probability of defects such as cracks during the cladding process. Simultaneously, the wear resistance, high temperature resistance, and impact resistance of the angle steel roller of this invention are significantly improved compared to welding or casting. After being put into production, its service life is increased by approximately 2 to 3 times compared to traditional welded or cast angle steel rollers, eliminating the need for frequent replacements and reducing operating costs. Detailed Implementation

[0020] To better understand the present invention, the materials and processes of the present invention will be further described in detail below with reference to the embodiments.

[0021] The strengthening process of the angle steel pressure roller of the present invention includes the following steps:

[0022] ① Machining: Machin the original blank according to the drawings, wherein the outer circle of the pressure roller is turned to be 2mm smaller than the final size of the roller;

[0023] ② Pre-inspection: Perform colorimetric and ultrasonic testing on the machined conveyor rollers to ensure that the rollers are free of defects such as cracks, air holes, and inclusions;

[0024] ③ Laser cladding: Iron-based alloy powder is clad onto the surface of the pressure roller. The chemical composition and mass percentage are: 13-19% Cr, 0.8-2.1% Ni, 0.5-1.5% Mo, 0.8-2% B, 1.0-1.8% Si, <0.5% C, <1.0% Mn, with the balance being Fe.

[0025] ④ Turning: Finish turning the roller surface to the final required dimensions and tolerances;

[0026] ⑤ Post-flaw inspection: After precision machining, the pressure roller is subjected to colorimetric and ultrasonic flaw inspection to ensure that the pressure roller is free of defects such as cracks and air holes.

[0027] In step ③, laser cladding, the pressure roller is preheated to 100-150℃ before cladding. Preheating the pressure roller reduces the risk of cracking of the cladding layer, while also avoiding poor cladding formation due to excessive temperature and preventing the appearance of pores.

[0028] Among them, step ③ laser cladding: the cladding process parameters are: circular spot size φ5mm, laser power 3~4kW, scanning speed 12~18mm / s, powder feeding rate 40~65g / min, and overlap rate 40%~60%.

[0029] In step ③, laser cladding, the thickness of the alloy powder cladding layer is 1.7–1.9 mm.

[0030] Example 1

[0031] When the base material of the angle steel pressure roller is 35CrMo and the dimensions are... At that time, its strengthening process is as follows:

[0032] ① Machining: The original blank is machined according to the drawings, including turning the outer diameter of the pressure roller to...

[0033] ② Pre-inspection: Perform colorimetric and ultrasonic testing on the machined pressure rollers to ensure that the rollers are free of defects such as cracks, air holes, and inclusions;

[0034] ③ Laser cladding: Before cladding, the angle steel pressure roller is preheated to 135℃. Then, an iron-based alloy powder with the following composition is used for laser cladding: 18% Cr, 1.8% Ni, 1.1% Mo, 1.5% B, 1.2% Si, <0.2% C, <0.6% Mn, with the balance being Fe. The process parameters for cladding are: circular spot size φ5mm, laser power 3.5kW, scanning speed 15mm / s, powder feeding rate 48g / min, overlap rate 50%; cladding layer thickness is 1.75mm.

[0035] ④ Turning: Finish turn the roller surface to...

[0036] ⑤ Post-inspection: Colorimetric and ultrasonic testing are performed on the precision-machined angle steel rolls to ensure that the rolls are free of defects such as cracks and pores.

[0037] Example 2

[0038] When the base material of the angle steel pressure roller is Q345 and the dimensions are... At that time, its strengthening process is as follows:

[0039] ① Machining: The original blank is machined according to the drawings, including turning the outer diameter of the pressure roller to...

[0040] ② Pre-inspection: Perform colorimetric and ultrasonic testing on the machined pressure rollers to ensure that the rollers are free of defects such as cracks, air holes, and inclusions;

[0041] ③ Laser cladding: Before cladding, the angle steel pressure roller is preheated to 120℃. Then, an iron-based alloy powder with the following composition is used for laser cladding: 16% Cr, 1.7% Ni, 1.2% Mo, 1.2% B, 1.4% Si, <0.2% C, <0.7% Mn, with the balance being Fe. The process parameters for cladding are: circular spot size φ5mm, laser power 3.6kW, scanning speed 12mm / s, powder feeding rate 44g / min, overlap rate 50%; cladding thickness on one side 1.82mm.

[0042] ④ Turning: Finish turn the roller surface to...

[0043] ⑤ Post-inspection: Colorimetric and ultrasonic testing are performed on the finely ground rollers to ensure that the rollers are free of defects such as cracks and air holes.

[0044] Example 3

[0045] When the base material of the angle steel pressure roller is ZG35Mn and the dimensions are... At that time, its strengthening process is as follows:

[0046] ① Machining: The original blank is machined according to the drawings, including turning the outer diameter of the roller to...

[0047] ② Pre-inspection: Perform colorimetric and ultrasonic testing on the machined pressure rollers to ensure that the rollers are free of defects such as cracks, air holes, and inclusions;

[0048] ③ Laser cladding: Before cladding, the angle steel pressure roller is preheated to 130℃. Then, an iron-based alloy powder with the following composition is used for laser cladding: 17.2% Cr, 1.6% Ni, 1% Mo, 1.3% B, 1.0% Si, <0.2% C, <0.5% Mn, with the balance being Fe. The cladding process parameters are: circular spot size φ5mm, laser power 3.8kW, scanning speed 18mm / s, powder feeding rate 58g / min, overlap rate 50%; cladding thickness on one side 1.7mm.

[0049] ④ Turning: Finish turn the roller surface to...

[0050] ⑤ Post-inspection: Colorimetric and ultrasonic testing are performed on the finely ground rollers to ensure that the rollers are free of defects such as cracks and air holes.

[0051] To verify the effectiveness of the materials and methods of this invention, the prepared cladding layer underwent corresponding performance tests and was compared with weld overlay coatings and cast samples. The experiments mainly included a 600℃ wear test to assess its wear resistance, an 850℃ oxidation test to assess its high-temperature oxidation resistance, and an impact test to assess its impact resistance. The wear test was conducted on a high-temperature end-face friction and wear testing machine at 600℃, using Al2O3 as the friction pair. The wear volume was obtained using a laser confocal microscope. The oxidation test involved heating the sample to 800℃, holding it at that temperature for 24 hours, allowing it to cool naturally to room temperature, and then weighing it to measure the weight gain after oxidation. The impact test was conducted on a self-made drop hammer impact testing machine, using a 5kg steel ball dropped from different heights to impact the sample surface sequentially. The impact energy was calculated based on the crack depth and the sample's withstand height. The test results are shown in Table 1.

[0052] Table 1 Comparison of performance of different coatings

[0053]

[0054] As can be seen from Table 1, the angle steel rollers obtained by using the wear-resistant layer material and strengthening process of the present invention have significantly improved wear resistance, high temperature resistance, and impact resistance compared to those obtained by welding or casting. After being put into use, their service life is about 2 to 3 times longer than that of traditional welded or cast angle steel rollers, eliminating the need for frequent replacements and reducing their operating costs.

[0055] This invention utilizes laser cladding to strengthen angle steel rollers with iron-based alloy materials. Specifically, a high-energy laser beam irradiates the workpiece surface, causing localized melting of the roller surface, which then melts and mixes with a surface-modifying material. Compared to traditional welding, surfacing, and spraying techniques, this is a non-contact surface treatment technology that allows for precise control of the melting depth and location, as well as the proportion and uniformity of the added material. Therefore, the laser cladding strengthening method of this invention has a relatively small heat-affected zone, reducing the cross-contamination problems of deformation and cracking in the base material. This results in a metallurgical bond between the various materials, improving the overall performance of the workpiece. Furthermore, it achieves high-precision and high-quality surface treatment of the workpiece without damaging the base material.

Claims

1. The strengthening process of angle steel pressure rollers, characterized by: The strengthening process includes the following steps: ① Machining: Machin the original blank according to the drawings, wherein the outer circle of the pressure roller is turned to be 2mm smaller than the final size of the roller; ② Pre-inspection: Colorimetric and ultrasonic testing are performed on the machined angle steel rollers to ensure that the rollers are free of cracks, pores, and inclusions. ③ Laser cladding: Iron-based alloy powder is clad onto the surface of the pressure roller. The chemical composition and mass percentage of the iron-based alloy powder are as follows: 15.8-19%Cr, 1.5~1.9%Ni, 0.9~1.3%Mo, 1.0~1.7%B, 1.0~1.5%Si, <0.2%C, <0.7%Mn, with the balance being Fe; ④ Turning: Finish turning the roller surface to the final required dimensions and tolerances; ⑤ Post-flaw inspection: Perform colorimetric and ultrasonic flaw inspection on the precision-machined pressure rollers to ensure that the pressure rollers are free of cracks and porosity defects; In step ③, laser cladding: the pressure roller is preheated before cladding, with a preheating temperature of 100~150℃. The cladding process parameters are: circular spot size φ5mm, laser power 3~4kW, scanning speed 12~18mm / s, powder feeding rate 40~65g / min, and overlap rate 40%~60%.

2. The strengthening process of the angle steel pressure roller according to claim 1, characterized in that: The iron-based alloy powder is produced by gas atomization powder preparation, and the powder particle size is 53μm-150μm.

3. The strengthening process of the angle steel pressure roller according to claim 1, characterized in that: Step ③ Laser cladding: The thickness of the alloy powder cladding layer is 1.7~1.9mm.

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