A method for surface strengthening of the air intake edge of an integral bladed disk blade

Abstract

This invention pertains to surface treatment technology for parts, specifically a method for surface strengthening of the inlet edge of an integral bladed disk blade. The method fully leverages the characteristics of two-phase flow strengthening, dry shot peening, ultra-high frequency laser shot peening, and high-energy laser shock peening. Based on the varying cross-sectional thicknesses of different regions on the inlet edge, differentiated strengthening processes are employed to construct surface residual compressive stress layers of varying depths. This not only significantly reduces blade deformation but also fully utilizes the fatigue performance gains of surface strengthening technology, meeting the dual requirements of resistance to foreign object damage fatigue on the inlet edge and resistance to high-cycle fatigue in critical sections. Numerical simulation is used to analyze the residual stress distribution on the blade surface, providing a reference for process implementation and reducing the number of trial and error attempts and workload.

Description

Technical Field

[0001] This invention pertains to surface treatment technology for parts, and relates to a method for surface strengthening of the air intake edge of an integral bladed disk blade. Background Technology

[0002] The integral bladed disk (IBD) of the compressor is a critical rotor component of an aero-engine, located at the front end. Its aerodynamic performance and long service life are key technical indicators for aero-engines. The blade structure of the IBD is complex, with the inlet edge being one of the most critical parts. The cross-sectional thickness of the inlet edge varies from 0.1 to 10 mm, and its profile dimensions have a significant impact on aerodynamic performance. Furthermore, the inlet edge faces notch damage from high-speed impacts from foreign objects such as sand and hail during service, and is prone to fatigue crack initiation and propagation under alternating loads. Additionally, the portion of the inlet edge near the disk body is also susceptible to high-cycle fatigue failure due to high-frequency vibration. These two fatigue failure modes can easily lead to blade fracture failure, resulting in a serious problem of insufficient service life for the aero-engine.

[0003] Currently, to improve the fatigue resistance of blade inlet edges to foreign object damage, low-intensity shot peening is commonly used for surface strengthening. However, the residual compressive stress layer generated by shot peening is relatively shallow, insufficient to meet the fatigue resistance requirements under high stress concentration conditions caused by foreign object damage. Increasing the shot peening intensity leads to dimensional deviations in the blade inlet edge profile, severely impacting aerodynamic performance. To address this issue, high-energy laser shock peening technology is employed both domestically and internationally to introduce a deeper residual compressive stress layer, thereby improving resistance to fatigue crack propagation. However, even after high-energy laser shock peening, inlet edge regions with a cross-sectional thickness of less than 1 mm still exhibit severe bending deformation, failing to meet dimensional requirements. Therefore, a novel surface strengthening technology is urgently needed to meet the dual requirements of overall fatigue resistance to foreign object damage in the blade inlet edge and post-processing dimensional control. Summary of the Invention

[0004] The purpose of this invention is to propose a surface strengthening method for the air intake edge of an integral bladed disk. This method aims to solve the problem of simultaneously achieving the desired fatigue resistance to foreign object damage and the control of post-processing contour dimensions for the air intake edge of blades with a large range of cross-sectional thickness variations, as is currently the case with shot peening or high-energy laser shock strengthening.

[0005] The technical solution of the present invention is: a surface strengthening method for the leading edge of an integral blisk blade. The integral blisk blade is composed of a disk body 1 and a blade 2. The leading edge 3 of the blade 2 accounts for 1 / 2 of the entire blade. The leading edge 3 is divided into four regions: a front end fillet 3-1, an intermediate cross-section region 3-2, a near-blade-body cross-section region 3-3, and a dangerous cross-section region 3-4. The front end fillet 3-1 is located at the bottom of the leading edge 3, and the cross-section thickness d does not exceed 1 mm. The intermediate cross-section region 3-2 is located above the front end fillet 3-1, and the cross-section thickness d is 1 < d ≤ 3 mm. The near-blade-body cross-section 3-3 is located above the intermediate cross-section region 3-2, and the cross-section thickness 3 < d ≤ 10 mm. The dangerous cross-section region 3-4 is located on the right side of the disk body 1, above the front end fillet 3-1, and on the left side of the intermediate cross-section region 3-2 and the near-blade-body cross-section 3-3, and the cross-section thickness 1 < d ≤ 10 mm. The strengthening sequence and process method for the above regions are as follows: first, high-energy laser shock strengthening is carried out on the dangerous cross-section region 3-4, then ultra-high-frequency laser shot peening is carried out on the intermediate cross-section region 3-2, then dry shot peening is carried out on the intermediate cross-section region 3-2, the near-blade-body cross-section 3-3, and the dangerous cross-section region 3-4, and finally, two-phase flow strengthening is carried out on the front end fillet 3-1.

[0006] The process parameters of the two-phase flow strengthening adopted for the front end fillet 3-1 are AGB9 or AGB15 glass beads, the shot peening intensity is 0.03 N to 0.20 N, and the coverage rate is 100% to 200%.

[0007] The process parameters of the ultra-high-frequency laser shot peening adopted for the intermediate cross-section region 3-2 are that the laser power density is 1.0 to 4.9 GW / cm 2 , the spot diameter is Φ0.1 to Φ0.5 mm, the overlapping rate is 30% to 70%, the processing frequency is 100 to 500 Hz, the water beam and the light beam are coaxial, and the water beam diameter is Φ1 to Φ3 mm.

[0008] The process parameters of the dry shot peening are AZB150 or AZB100 ceramic beads, the shot peening intensity is 0.10 to 0.30 N, and the coverage rate is 100% to 200%.

[0009] The process parameters of the high-energy laser shock strengthening are that the laser power density is 1.0 to 6.0 GW / cm 2 , the spot diameter is Φ1.5 to Φ5 mm, the overlapping rate is 30% to 70%, the processing frequency is 1 to 5 Hz, and the thickness of the water confinement layer is 1 to 2 mm.

[0010] For the intermediate cross-section region 3-2 and the dangerous cross-section region 3-4, a double-sided asynchronous impact method is adopted. First, the blade concave surface is impacted once, and then the blade convex surface is impacted once. Allowing for one-time shape correction, the spot scanning method is to scan in a "zigzag" shape from the disk body 1 towards the blade tip, first scanning the region with a larger thickness, and then scanning the region with a smaller thickness.

[0011] Before the impact, a three-dimensional model of blade 2 was obtained, and then the Johnson-Cook constitutive model of blade 2 was established. Then, the distribution of residual compressive stress on the surface after the impact was numerically simulated to determine the shape and size of the three regions: the front fillet 3-1, the middle section region 3-2, the near-blade section region 3-3, and the critical section region 3-4.

[0012] The transition zone range of the four regions—front fillet 3-1, intermediate section region 3-2, near-blade section region 3-3, and critical section region 3-4—is 0–1.0 mm.

[0013] The advantages of this invention are:

[0014] First, high-energy laser shock blasting is performed on the critical section region 3-4 because the critical section region 3-4 has the largest thickness (4-10 mm). High-energy laser shock blasting can obtain a deep residual compressive stress field with a depth of 1-2 mm.

[0015] Then, the intermediate section region 3-2 is subjected to ultra-high frequency laser shot peening. The thickness of the intermediate section region 3-2 is about 1 to 4 mm. By ultra-high frequency laser shot peening, a residual compressive stress field (depth about 0.25 to 0.5 mm) matching the thickness is constructed.

[0016] Secondly, dry shot peening is performed on the intermediate section region 3-2, the near-blade section 3-3, and the critical section region 3-4. The residual compressive stress field generated by dry shot peening does not exceed 0.25 mm. Through repeated impacts of the shot during the dry shot peening process, uniform and high-amplitude surface residual compressive stress values ​​are obtained in the high-frequency laser shot peening, high-energy laser shot peening, and unpeened areas.

[0017] Finally, two-phase flow strengthening was applied to the front fillet 3-1. Since the thickness of the front fillet 3-1 is less than 1 mm, the residual compressive stress field generated by high-energy and ultra-high-frequency laser shot peening has a depth exceeding 1 / 2 of the thickness, making the front fillet prone to severe deformation. Furthermore, dry shot peening produces excessively high surface roughness values ​​(Ra 1.2–2.0 μm), severely affecting aerodynamic performance. Therefore, two-phase flow strengthening was employed, using a water + shot two-phase flow to repeatedly impact the surface. This not only yields a uniform, high-amplitude surface residual compressive stress value but also achieves a lower surface roughness value (≤ Ra 0.6 μm).

[0018] It is worth mentioning that the intermediate section region 3-2 is strengthened first, followed by the front fillet 3-1. This order is crucial because it allows for a better residual compressive stress field at the interface between the two regions. Conversely, it would result in excessive residual tensile stress distribution within the front fillet 3-1. Secondly, high-energy and ultra-high-frequency laser peening is performed first, followed by dry peening and two-phase flow strengthening. This order is also crucial because dry peening and two-phase flow strengthening result in higher degrees of plastic deformation. Post-laser peening treatment can achieve a uniform, high-amplitude surface residual compressive stress distribution. Conversely, performing the latter would result in an uneven distribution of surface residual compressive stress.

[0019] This invention fully leverages the characteristics of two-phase flow strengthening, dry shot peening, ultra-high frequency laser shot peening, and high-energy laser shock peening. Based on the varying cross-sectional thicknesses of different regions along the blade inlet edge, differentiated strengthening processes are employed to construct surface residual compressive stress layers of varying depths. This not only significantly reduces blade deformation but also fully utilizes the fatigue performance gains of surface strengthening technology, meeting the dual requirements of resistance to foreign object damage fatigue at the inlet edge and resistance to high-cycle fatigue at critical sections. Numerical simulation is used to analyze the residual stress distribution on the blade surface, providing a reference for process implementation and reducing the number of trial and error attempts and workload. Attached Figure Description

[0020] Figure 1 Schematic diagram of the laser-shock-enhanced area of ​​the blade;

[0021] Figure 2 Schematic diagram of residual stress distribution on the surface of the reinforced area.

[0022] Wherein: 1-Disc body, 2-Blade, 3-1-Tip fillet, 3-2-Intermediate section area, 3-3-Near blade section area, 3-4-Critical section area Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0024] like Figure 1 , Figure 2As shown in the figure, a surface strengthening method for the leading edge of an integral blisk blade. The integral blisk blade consists of a disk body 1 and a blade 2. The leading edge 3 of the blade 2 accounts for 1 / 2 of the entire blade. The leading edge 3 is divided into four regions: a front-end fillet 3-1, an intermediate cross-section region 3-2, a near-blade-body cross-section region 3-3, and a critical cross-section region 3-4. The front-end fillet 3-1 is located at the bottom of the leading edge 3, and the cross-section thickness d does not exceed 1 mm. The intermediate cross-section region 3-2 is located above the front-end fillet 3-1, and the cross-section thickness d is 1 < d ≤ 3 mm. The near-blade-body cross-section 3-3 is located above the intermediate cross-section region 3-2, and the cross-section thickness 3 < d ≤ 10 mm. The critical cross-section region 3-4 is located on the right side of the disk body 1, above the front-end fillet 3-1, and on the left side of the intermediate cross-section region 3-2 and the near-blade-body cross-section 3-3, and the cross-section thickness 1 < d ≤ 10 mm. The strengthening sequence and process method for the above regions are as follows: first, perform high-energy laser shock strengthening on the critical cross-section region 3-4, then perform ultra-high-frequency laser peening on the intermediate cross-section region 3-2, then perform dry peening on the intermediate cross-section region 3-2, the near-blade-body cross-section 3-3, and the critical cross-section region 3-4, and finally perform two-phase flow strengthening on the front-end fillet 3-1.

[0025] The process parameters for the two-phase flow strengthening used for the front-end fillet 3-1 are AGB9 or AGB15 glass beads, the peening intensity is 0.03 N to 0.20 N, and the coverage rate is 100% to 200%.

[0026] The process parameters for the ultra-high-frequency laser peening used for the intermediate cross-section region 3-2 are that the laser power density is 1.0 to 4.9 GW / cm 2 , the spot diameter is Φ0.1 to Φ0.5 mm, the overlapping rate is 30% to 70%, the processing frequency is 100 to 500 Hz, the water beam and the light beam are coaxial, and the water beam diameter is Φ1 to Φ3 mm.

[0027] The process parameters for the dry peening are AZB150 or AZB100 ceramic beads, the peening intensity is 0.10 to 0.30 N, and the coverage rate is 100% to 200%.

[0028] The process parameters for the high-energy laser shock strengthening are that the laser power density is 1.0 to 6.0 GW / cm 2 , the spot diameter is Φ1.5 to Φ5 mm, the overlapping rate is 30% to 70%, the processing frequency is 1 to 5 Hz, and the thickness of the water confinement layer is 1 to 2 mm.

[0029] For the intermediate cross-section region 3-2 and the critical cross-section region 3-4, a double-sided asynchronous impact method is used. First, impact the blade concave surface once, then impact the blade convex surface once, and allow for one-time shape correction. The spot scanning method is to scan in a "zigzag" shape from the disk body 1 towards the blade tip, first scanning the region with a larger thickness, and then scanning the region with a smaller thickness.

[0030] Before the impact, a three-dimensional model of blade 2 was obtained, and then the Johnson-Cook constitutive model of blade 2 was established. Then, the distribution of residual compressive stress on the surface after the impact was numerically simulated to determine the shape and size of the three regions: the front fillet 3-1, the middle section region 3-2, the near-blade section region 3-3, and the critical section region 3-4.

[0031] The transition zone range of the four regions—front fillet 3-1, intermediate section region 3-2, near-blade section region 3-3, and critical section region 3-4—is 0–1.0 mm.

[0032] The working principle of this invention is:

[0033] Surface strengthening technology improves overall fatigue performance by creating a residual compressive stress layer on the surface of parts, thereby increasing the resistance to fatigue crack initiation and propagation. The residual compressive stress layer must match the cross-sectional thickness of the part to achieve coordinated control of deformation and fatigue performance improvement. When the depth exceeds half the cross-sectional thickness, a matching residual compressive stress will be generated on the surface of another part of the cross-section, leading not only to a decrease in fatigue performance in that area but also to overall bending deformation of the cross-section. Since the inlet edge of the blade is a thin-walled structure, with a cross-sectional thickness typically ranging from 0.1 to 10 mm, a single surface strengthening technology cannot meet the requirements. The residual compressive stress layer depths produced by four processes—two-phase flow strengthening, dry shot peening, ultra-high frequency laser shot peening, and high-energy laser shock peening—are 0.01–0.1 mm, 0.1–0.2 mm, 0.2–1 mm, and 1–2 mm, respectively. Therefore, to meet the requirements of coordinated control of blade shape and properties, different surface strengthening processes must be adopted according to the cross-sectional thickness of the blade. Figure 2As shown, the cross-sectional thickness of the front-end rounded corner 3-1 does not exceed 1 mm. Therefore, the two-phase flow strengthening with a surface residual compressive stress layer depth of 0.01 mm to 0.1 mm is the most suitable process method; the cross-sectional thickness of the middle cross-section area 3-2 is 1 to 3 mm. This part is a high-incidence area of foreign object damage, and the notch stress concentration urgently requires a deep and uniform residual compressive stress layer to inhibit the initiation and propagation of fatigue cracks. Therefore, the composite strengthening of ultra-high-frequency laser peening and dry peening is the most suitable process method, and the composite strengthening can construct a deep and uniform residual compressive stress layer. The cross-sectional thickness of the near-blade cross-section 3-3 is 3 < d ≤ 10 mm. The processing efficiency of dry peening is higher than that of ultra-high-frequency laser peening and high-energy laser shock peening. Therefore, the dry peening strengthening technology is preferred. The cross-sectional thickness of the dangerous cross-section area 3-4 is 1 < d ≤ 10 mm. This area is a high-incidence area of high-cycle fatigue. Therefore, high-energy laser shock peening is carried out first, and then dry peening is carried out, which is beneficial to constructing a deep and uniform residual compressive stress layer and achieving the goal of resisting high-cycle fatigue. Research shows that strengthening the blade concave surface first and then the blade convex surface results in less overall deformation of the blade concave surface because the structural stiffness of the blade concave surface is less than that of the blade convex surface. Through numerical simulation, the residual stress distribution on the blade surface is analyzed to provide a reference for process implementation, reducing the number of process trials and the workload.

[0034] Example 1

[0035] The integral blisk blade is composed of a disk body 1 and a blade 2. The intake edge 3 of the blade 2, which accounts for 1 / 2 of the entire blade, is divided into four regions: the front-end rounded corner 3-1, the middle cross-section area 3-2, the near-blade cross-section area 3-3, and the dangerous cross-section area 3-4; the front-end rounded corner 3-1 is located at the bottom of the intake edge 3, and the cross-sectional thickness d does not exceed 1 mm; the middle cross-section area 3-2 is located above the front-end rounded corner 3-1, and the cross-sectional thickness d is 1 < d ≤ 3 mm; the near-blade cross-section 3-3 is located above the middle cross-section area 3-2, and the cross-sectional thickness is 3 < d ≤ 10 mm; the dangerous cross-section area 3-4 is located on the left side of the disk body 1, above the front-end rounded corner 3-1, and on the left side of the middle cross-section area 3-2 and the near-blade cross-section 3-3, and the cross-sectional thickness is 1 < d ≤ 10 mm; the strengthening sequence and process method for the above regions are as follows: high-energy laser shock peening is carried out on the dangerous cross-section area 3-4 first, then ultra-high-frequency laser peening is carried out on the middle cross-section area 3-2, then dry peening is carried out on the middle cross-section area 3-2, the near-blade cross-section 3-3, and the dangerous cross-section area 3-4, and finally two-phase flow strengthening is carried out on the front-end rounded corner 3-1.

[0036] The process parameters of the two-phase flow strengthening used for the front-end rounded corner 3-1 are AGB9 glass beads, the peening intensity is 0.03 N to 0.20 N, and the coverage rate is 100% to 200%;

[0037] The ultra-high frequency laser peening process used in the intermediate cross-section region 3-2 has a laser power density of 1.0 GW / cm². 2 The beam spot diameter is Φ0.1mm, the overlap rate is 70%, the processing frequency is 100Hz, the water jet is coaxial with the beam, and the water jet diameter is Φ1mm;

[0038] The process parameters for dry shot peening are AZB150 ceramic shot, shot peening intensity of 0.10-0.30 N, and coverage of 100%-200%;

[0039] The process parameters for high-energy laser shock peening are a laser power density of 1.0 GW / cm². 2 The spot diameter is Φ1.5mm, the overlap rate is 30%, the processing frequency is 1Hz, and the water constraint layer thickness is 2mm.

[0040] For the intermediate section area 3-2 and the dangerous section area 3-4, a double-sided asynchronous impact method is adopted. The blade basin surface is impacted once, and then the back surface of the blade is impacted once. One correction is allowed. The spot scanning method is to scan in a "zigzag" pattern from the disk body 1 towards the blade tip, first scanning the thicker area and then scanning the thinner area.

[0041] Before the impact, a three-dimensional model of blade 2 is obtained, and then a constitutive model of blade 2 is established. Then, numerical simulation is performed on the distribution of residual compressive stress on the surface after the impact to determine the shape and size of the three regions: the front fillet 3-1, the middle section region 3-2, the near-blade section region 3-3, and the critical section region 3-4.

[0042] The transition zone range of the four regions—front fillet 3-1, intermediate section region 3-2, near-blade section region 3-3, and critical section region 3-4—is 0–1.0 mm.

[0043] Example 2

[0044] The front-end rounded corner 3-1 uses a two-phase flow strengthening process with AGB15 glass shot, a shot peening intensity of 0.03N to 0.20N, and a coverage of 100% to 200%.

[0045] The ultra-high frequency laser peening process used in the intermediate cross-section region 3-2 has a laser power density of 4.9 GW / cm². 2 The beam spot diameter is Φ0.5mm, the overlap rate is 30%, the processing frequency is 500Hz, the water jet is coaxial with the beam, and the water jet diameter is Φ3mm;

[0046] The process parameters for dry shot peening are AZB100 ceramic shot, shot peening intensity of 0.10-0.30 N, and coverage of 100%-200%;

[0047] The process parameters for high-energy laser shock peening are a laser power density of 6.0 GW / cm². 2 The spot diameter is Φ5mm, the overlap rate is 70%, the processing frequency is 5Hz, and the water constraint layer thickness is 1mm.

Claims

1. A method for surface strengthening of the air intake edge of an integral bladed disk blade, characterized in that: The blisk blade consists of a disk body (1) and a blade (2). The inlet edge (3) of the blade (2) accounts for 1 / 2 of the entire blade. The inlet edge (3) is divided into four regions: a front-end rounded corner (3-1), a middle cross-section region (3-2), a near-blade-body cross-section region (3-3), and a dangerous cross-section region (3-4). The front-end rounded corner (3-1) is located at the lower part of the inlet edge (3), and the cross-section thickness d does not exceed 1 mm. The middle cross-section region (3-2) is located above the front-end rounded corner (3-1), and the cross-section thickness d is 1 < d ≤ 3 mm. The near-blade-body cross-section region (3-3) is located above the middle cross-section region (3-2), and the cross-section thickness is 3 < d ≤ 10 mm. The dangerous cross-section region (3-4) is located on the right side of the disk body (1), above the front-end rounded corner (3-1), and on the left side of the middle cross-section region (3-2) and the near-blade-body cross-section region (3-3), and the cross-section thickness is 1 < d ≤ 10 mm. The strengthening sequence and process method are as follows: First, high-energy laser shock strengthening is carried out on the dangerous cross-section region (3-4), then ultra-high-frequency laser peening is carried out on the middle cross-section region (3-2), then dry peening strengthening is carried out on the middle cross-section region (3-2), the near-blade-body cross-section region (3-3), and the dangerous cross-section region (3-4), and finally two-phase flow strengthening is carried out on the front-end rounded corner (3-1). The two-phase flow strengthening is achieved by repeatedly impacting the surface with a water + shot two-phase flow.

2. The surface strengthening method for the air intake edge of an integral bladed disk according to claim 1, characterized in that: The front fillet (3-1) uses a two-phase flow strengthening process with AGB9 or AGB15 glass pellets, a shot peening intensity of 0.03N~0.20N, and a coverage of 100%~200%.

3. The surface strengthening method for the air intake edge of an integral bladed disk according to claim 1, characterized in that: The intermediate cross-sectional region (3-2) was treated with ultra-high frequency laser peening with laser power density ranging from 1.0 to 4.9 GW / cm². 2 The beam spot diameter is Φ0.1~Φ0.5mm, the overlap rate is 30%~70%, the processing frequency is 100~500Hz, the water jet is coaxial with the beam, and the water jet diameter is Φ1~Φ3mm.

4. The surface strengthening method for the air intake edge of an integral bladed disk according to claim 1, characterized in that: The dry shot peening process parameters are AZB150 or AZB100 ceramic shot, shot peening intensity of 0.10~0.30N, and coverage of 100%~200%.

5. The surface strengthening method for the air intake edge of an integral bladed disk according to claim 1, characterized in that: The process parameters for high-energy laser shock peening are a laser power density of 1.0~6.0 GW / cm². 2 The spot diameter is Φ1.5~Φ5mm, the overlap rate is 30%~70%, the processing frequency is 1~5Hz, and the water constraint layer thickness is 1~2mm.

6. The surface strengthening method for the air intake edge of an integral bladed disk according to claim 1, characterized in that: For the intermediate section area (3-2) and the dangerous section area (3-4), a double-sided asynchronous impact method is adopted. The blade basin surface is impacted once, and the back surface of the blade is impacted once. One correction is allowed. The light spot scanning method is to scan in a "zigzag" pattern from the disc body (1) to the blade tip. First, the thicker area is scanned, and then the thinner area is scanned.

7. The surface strengthening method for the air intake edge of an integral bladed disk according to claim 1, characterized in that: Before the impact, a three-dimensional model of the blade (2) is obtained, and then the Johnson-Cook constitutive model of the blade (2) is established. Then, the distribution of residual compressive stress on the surface after the impact is numerically simulated to determine the shape and size of the four regions: the front fillet (3-1), the middle section region (3-2), the near-blade section region (3-3), and the dangerous section region (3-4).

8. The surface strengthening method for the air intake edge of an integral bladed disk according to claim 1, characterized in that: The transition zone range of the four regions—the front fillet (3-1), the middle section region (3-2), the near-blade section region (3-3), and the critical section region (3-4)—is 0~1.0 mm.

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