Production process of high-strength corrosion-resistant power transmission pole cross arm

Abstract

The invention discloses a production process of a high-strength anti-corrosion power transmission pole cross arm. The production process comprises the following steps that 1, an anti-SCC aluminum alloy is selected; a trace amount of Sc is added to refine grains, so that the corrosion resistance is improved; cold machining is avoided, and a warm forming process is adopted; 2, aluminum alloy ingot smelting and hot extrusion forming are carried out; 3, T6 solid solution treatment is carried out to improve the strength; 4, the five-axis CNC machining center conducts structural topology optimization cutting; the surface roughness Ra of a key bearing part is less than or equal to 0.8 mu m; an ultrasonic-assisted drilling technology is adopted; step 5, micro-arc oxidation; and step 6, ultrasonic flaw detection and infrared thermal imaging. The 5083-H116 aluminum alloy is combined with Sc microalloying, precision machining and micro-arc oxidation technologies, so that the stress corrosion resistance is improved by 3 times, the fatigue life is prolonged by 2-3 times while the tensile strength of the power transmission pole cross arm is kept to be larger than or equal to 350 MPa, 5000-hour salt mist protection and 30-year maintenance-free are achieved, and the service life of the power transmission pole cross arm is prolonged. The problems of corrosion cracking, short fatigue life and insufficient durability of a traditional product in a harsh environment are comprehensively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-strength corrosion-resistant transmission pole cross arms, and more specifically, relates to a production process for high-strength corrosion-resistant transmission pole cross arms. Background Art

[0002] The high-strength, corrosion-resistant transmission pole crossarm is a key load-bearing component of the power transmission system made of special alloy materials (such as 5083-H116 aluminum alloy) and advanced manufacturing technology. Through processes such as micro-alloying modification, precision hot forming and micro-arc oxidation surface treatment, it has excellent mechanical properties (tensile strength ≥350MPa), outstanding corrosion resistance (C5 grade corrosion resistance) and long-term environmental adaptability (design life ≥30 years). It is specially designed for high-voltage transmission lines in harsh corrosive environments such as coastal areas and industrial areas, and can significantly improve the reliability and service life of power grid facilities.

[0003] However, the main technical challenges faced by traditional transmission pole crossarms in harsh environments include: The material is prone to stress corrosion cracking, especially in corrosive environments such as high salt spray and high humidity, where aluminum alloy components are prone to intergranular corrosion and stress corrosion cracking; Insufficient fatigue life. Due to the large surface roughness (Ra>1.6μm) and stress concentration caused by traditional processing technology, early fatigue failure is prone to occur under dynamic loads; The long-term corrosion resistance is poor, and the protective performance of conventional surface treatments such as anodizing is limited. It is difficult to meet the service life requirement of more than 30 years in harsh environments such as coastal areas. Summary of the Invention

[0004] The purpose of the present invention is to address the shortcomings of the prior art. The present invention adopts 5083-H116 aluminum alloy in combination with Sc micro-alloying, precision machining and micro-arc oxidation technology, so that the stress corrosion resistance of the transmission pole crossarm is increased by 3 times, the fatigue life is increased by 2-3 times, while maintaining a tensile strength of ≥350MPa, and 5000 hours of salt spray protection and 30 years of maintenance-free are achieved. The key technical problems of traditional products such as corrosion cracking, short fatigue life and insufficient durability in harsh environments are comprehensively solved; and a production process for high-strength and corrosion-resistant transmission pole crossarms is proposed.

[0005] To achieve the above object, the present invention provides the following technical solutions: A production process for high-strength, corrosion-resistant transmission pole crossarms, comprising the following steps: Step 1: Select SCC-resistant aluminum alloy; add trace amounts of Sc to refine grains and improve corrosion resistance; avoid cold working and adopt warm forming process; Step 2: melting aluminum alloy ingots and hot extrusion molding; Step 3: T6 solution treatment to improve strength; Step 4: Use a five-axis CNC machining center to perform structural topology optimization cutting; the surface roughness of key load-bearing parts is Ra ≤ 0.8μm; ultrasonic-assisted drilling technology is used; Step 5, micro-arc oxidation; Step 6: Ultrasonic flaw detection and infrared thermal imaging.

[0006] Preferably, in step 1, in the production process of the transmission pole crossarm, 5083-H116 aluminum alloy with excellent resistance to stress corrosion cracking (SCC) is selected to replace the traditional 7075 alloy. This key material significantly improves the environmental adaptability of the product through the following three optimization mechanisms: First, the β phase formed by the magnesium content in the 5083-H116 alloy has more stable electrochemical properties, fundamentally avoiding the intergranular corrosion sensitivity caused by the copper element in the 7075 alloy. Second, the addition of 0.1-0.3wt% scandium can form Al3Sc nano-precipitates during the solidification process, which not only refines the grain size to 1 / 3 of that of the traditional process, but also shifts the pitting corrosion potential positively by more than 200mV through the passivation effect of the Sc-O bond. Finally, the use of a warm forming process at 150-200℃ instead of cold working not only maintains 60-70% of the cold work hardening effect, but also reduces the residual stress to 1 / 5 of that of cold working. This thermal and mechanical synergistic regulation increases the stress corrosion threshold value (KISCC) of the product in a C4 level corrosion environment to 35MPa·m1 / 2, nearly three times higher than that of the traditional process.

[0007] Preferably, the SCC-resistant aluminum alloy material in step 1 is combined with subsequent micro-arc oxidation treatment to extend the service life of the crossarm in a coastal high-salt fog environment to over 30 years.

[0008] Preferably, in step 2, during the smelting and hot extrusion forming process of the aluminum alloy ingot for the transmission pole crossarm, the content of Fe and Cu impurity elements is strictly controlled to effectively avoid the formation of coarse intermetallic compounds and significantly improve the purity of the material; During the hot extrusion forming stage, a multi-stage diversion die design and isothermal extrusion technology are used, combined with a stress distribution scheme optimized by finite element simulation, to reduce the metal flow stress during the extrusion process by 15-20%. This not only eliminates the surface cracks and internal shrinkage defects common in traditional processes, but also controls the fluctuation range of the mechanical properties of the cross-arm section to within ±5%.

[0009] Preferably, in step 2, metallurgical purity control and plastic deformation are synergistically optimized to ensure that the product has both uniform fine-grained structure and excellent strength-toughness matching, thereby laying an ideal material foundation for subsequent heat treatment and surface treatment.

[0010] Preferably, in step 3, the T6 solution aging heat treatment is a key process for strengthening the aluminum alloy crossarm. The alloying elements are fully dissolved to form a supersaturated solid solution through solution treatment at 530°C ± 5°C, followed by water quenching to freeze the high-temperature microstructure, and then artificial aging at 175°C × 8h to promote the dispersion and precipitation of the GP zone and β" strengthening phase. This treatment increases the tensile strength of the 5083-H116 aluminum alloy from 260MPa to ≥350MPa while maintaining an elongation of more than 12%. In particular, by precisely controlling the aging parameters, the grain boundary precipitation phase is discontinuously distributed, thereby improving the strength while minimizing the stress corrosion sensitivity, thereby achieving the optimal balance of strength-plasticity-corrosion resistance.

[0011] Preferably, in step 4, in the precision machining of the transmission pole crossarm, a five-axis CNC machining center is used to implement structural topology optimization cutting, and a lightweight design driven by finite element analysis is used to increase material utilization by more than 40%, while ensuring that the stress concentration factor is controlled below 1.5; During the machining process, diamond tools are used for precision milling of key load-bearing parts to achieve ultra-precision surface with Ra≤0.8μm, which increases fatigue life by 2-3 times compared with conventional machining. In particular, ultrasonic-assisted drilling technology is introduced in the processing of connecting holes. The intermittent cutting effect generated by high-frequency vibration reduces the axial cutting force by 35%, the residual stress on the hole wall by 60%, and eliminates burrs, thereby reducing the micro-wear rate in the bolt connection area by more than 50%.

[0012] Preferably, the composite precision machining in step 4 achieves a breakthrough performance improvement of 20% in dynamic load bearing capacity while reducing the weight of the cross arm component by 15% through the three-level coordination of "macrostructure optimization-micro surface control-local process enhancement".

[0013] Preferably, in step 5, micro-arc oxidation is an advanced surface treatment technology for in-situ growth of a ceramic layer on the surface of an aluminum alloy. Its working principle is to immerse the aluminum alloy workpiece in an alkaline electrolyte and apply a high-voltage pulse power supply of 350-500V to induce micro-area discharge on the surface of the material. Under the action of plasma electrochemistry / thermodynamic coupling, the aluminum matrix reacts with the electrolyte components to in-situ generate a porous ceramic layer mainly composed of α-Al2O3; the 50-100μm ceramic layer formed by this technology has a unique "three-layer structure" with an outer layer of a porous wear-resistant layer, a dense barrier layer in the middle, and an inner layer of a metallurgical bonding transition layer, so that the crossarm surface can simultaneously obtain three core performance improvements: (1) The corrosion resistance is greatly enhanced, and the salt spray test is greater than 5000 hours without substrate corrosion; (2) Wear resistance is significantly improved, and the friction coefficient is reduced to 0.15-0.2; (3) Excellent insulation performance, breakdown voltage > 3000V / μm; in particular, the compressive residual stress in the ceramic layer effectively offsets the tensile stress during service, extending the stress corrosion crack initiation time of the crossarm in the strong coastal corrosion environment to more than 15 times that of the traditional process, achieving 30 years of maintenance-free service.

[0014] Preferably, in step 6, ultrasonic flaw detection and infrared thermal imaging technology constitute a dual guarantee system for non-destructive testing of transmission pole crossarms: ultrasonic flaw detection emits high-frequency sound waves through a piezoelectric transducer, and detects tiny defects ≥0.5mm based on the reflection / attenuation characteristics of sound waves by internal defects in the metal, with a positioning accuracy of ±0.1mm; infrared thermal imaging utilizes the difference in thermal conductivity caused by the delamination of composite materials, and captures the dynamic heat flow field through a high-sensitivity infrared camera to achieve rapid imaging detection of delamination defects ≥1mm²; these two technologies work together to increase the internal defect detection rate of metal crossarms to 99.9%, and the delamination identification sensitivity of composite crossarms is increased by 10 times, jointly ensuring that the product can serve without hidden dangers under extreme loads.

[0015] The technical effects and advantages of the present invention: The present invention provides a production process for a high-strength, corrosion-resistant transmission pole cross arm. Compared with the prior art, the present invention Through innovative material selection and process optimization, this invention effectively solves the three major technical problems faced by traditional transmission pole crossarms in harsh environments: Using 5083-H116 aluminum alloy instead of 7075 alloy, combined with Sc microalloying and warm forming process, the stress corrosion threshold is raised to 35MPa·m1 / 2, which is three times higher than the traditional process, completely solving the problem of stress corrosion cracking; Through five-axis CNC precision machining and ultrasonic-assisted drilling technology, the surface roughness of key parts is controlled to Ra≤0.8μm, which increases the fatigue life by 2-3 times and overcomes the defect of insufficient fatigue life; The 50-100μm ceramic layer, formed using micro-arc oxidation technology, surpasses 5,000 hours in salt spray testing, enabling 30 years of maintenance-free service and significantly improving long-term corrosion resistance. This entire process, encompassing innovations across the entire "materials-processing-structure-testing" chain, not only ensures a tensile strength of ≥350MPa but also increases the product's dynamic load-bearing capacity by 20% in highly corrosive environments, such as coastal areas. This provides technical support for the reliable operation of power grid facilities in these harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Example

[0018] In summary, the present invention provides a production process for high-strength, corrosion-resistant transmission pole crossarms, comprising the following steps: Step 1: Select an SCC-resistant aluminum alloy (such as 5083-H116 instead of 7075); add a small amount of Sc (scandium) to refine the grains and improve corrosion resistance; avoid cold working and use a warm forming process (150~200℃); Step 2: Aluminum alloy ingot smelting (controlling Fe and Cu impurity content) and hot extrusion molding (mold design needs to optimize stress distribution); Step 3: T6 solution treatment (530℃ water quenching + 175℃ artificial aging) to improve strength; Step 4: Use a five-axis CNC machining center to perform structural topology optimization cutting; the surface roughness of key load-bearing parts is Ra ≤ 0.8μm; ultrasonic-assisted drilling technology (amplitude 15μm, frequency 20kHz) is used; Step 5: Micro-arc oxidation (ceramic surface); Step 6: Ultrasonic flaw detection (internal defects in metals) and infrared thermal imaging (delamination of composite materials).

[0019] Preferably, in step 1, in the production process of the transmission pole crossarm, 5083-H116 aluminum alloy with excellent resistance to stress corrosion cracking (SCC) is selected to replace the traditional 7075 alloy. This key material significantly improves the environmental adaptability of the product through the following three optimization mechanisms: First, the β phase (Al3Mg2) formed by the magnesium content (4.0-4.9%) of the 5083-H116 alloy has more stable electrochemical properties, fundamentally avoiding the intergranular corrosion sensitivity caused by the copper element in the 7075 alloy. Second, the addition of 0.1-0.3wt% scandium (Sc) can form Al3Sc nano-precipitates during solidification, which not only refines the grain size to 1 / 3 of that of the traditional process (approximately 15-20μm) but also shifts the pitting corrosion potential positively by more than 200mV through the passivation effect of the Sc-O bond. Finally, the use of a warm forming process at 150-200℃ instead of cold working not only maintains 60-70% of the cold work hardening effect, but also reduces the residual stress to 1 / 5 of the cold working (<50MPa). This thermal and mechanical synergistic regulation increases the stress corrosion threshold value (KISCC) of the product in a C4 level corrosion environment to 35MPa·m1 / 2, nearly three times higher than that of the traditional process.

[0020] Preferably, the SCC-resistant aluminum alloy (such as 5083-H116 replacing 7075) material in step 1 is combined with subsequent micro-arc oxidation treatment to extend the service life of the crossarm in a coastal high salt fog environment to over 30 years.

[0021] Preferably, in step 2, during the smelting and hot extrusion forming process of the aluminum alloy ingot for the transmission pole crossarm, by strictly controlling the content of Fe (<0.4wt%) and Cu (<0.1wt%) impurity elements, the formation of coarse intermetallic compounds (such as FeAl3) can be effectively avoided, and the purity of the material can be significantly improved (inclusion size ≤10μm); During the hot extrusion forming stage, a multi-stage diversion die design (diversion angle 25-35°) and isothermal extrusion technology (blank temperature 450±5℃) are adopted, combined with a stress distribution scheme optimized by finite element simulation. This reduces the metal flow stress during the extrusion process by 15-20%. This not only eliminates the surface cracks and internal shrinkage defects common in traditional processes (defect rate <0.1%), but also controls the fluctuation range of the mechanical properties of the cross-arm section within ±5%.

[0022] Preferably, in step 2, by synergistic optimization of metallurgical purity control and plastic deformation, it is ensured that the product obtains uniform fine-grained structure (grain size level ≥8) while having excellent strength and toughness matching (elongation ≥12%), laying an ideal material foundation for subsequent heat treatment and surface treatment.

[0023] Preferably, in step 3, the T6 solution aging heat treatment is a key process for strengthening the aluminum alloy crossarm. The T6 solution aging heat treatment is performed at 530°C ± 5°C to fully dissolve the alloying elements (Mg, Si, etc.) to form a supersaturated solid solution, followed by water quenching (cooling rate > 200°C / s) to freeze the high-temperature microstructure, and then artificial aging at 175°C × 8h to promote the dispersion and precipitation of the GP zone and β" (Mg2Si) strengthening phase. This treatment increases the tensile strength of the 5083-H116 aluminum alloy from 260MPa to ≥350MPa (an increase of 35%) while maintaining an elongation of more than 12%. In particular, by precisely controlling the aging parameters to make the grain boundary precipitation phase discontinuously distributed, the strength is improved while the stress corrosion sensitivity is minimized (KISCC > 30MPa·m1 / 2), achieving an optimal balance of strength, plasticity, and corrosion resistance.

[0024] Preferably, in step 4, in the precision machining of the transmission pole crossarm, a five-axis CNC machining center is used to implement structural topology optimization cutting, and a lightweight design driven by finite element analysis is used to increase material utilization by more than 40%, while ensuring that the stress concentration factor (Kt) is controlled below 1.5; During the machining process, diamond tools are used for precision milling (feed speed 0.05mm / tooth) on key load-bearing parts to achieve an ultra-precision surface of Ra≤0.8μm, which increases the fatigue life by 2-3 times compared with conventional machining (Ra1.6μm); In particular, ultrasonic-assisted drilling technology (amplitude 15μm / frequency 20kHz) is introduced in the processing of connecting holes. The intermittent cutting effect generated by high-frequency vibration reduces the axial cutting force by 35%, the residual stress on the hole wall by 60%, and eliminates burrs, reducing the micro-wear rate in the bolt connection area by more than 50%.

[0025] Preferably, the composite precision machining in step 4 achieves a breakthrough performance improvement of 20% in dynamic load bearing capacity while reducing the weight of the cross arm component by 15% through the three-level coordination of "macrostructure optimization-micro surface control-local process enhancement".

[0026] Preferably, in step 5, micro-arc oxidation is an advanced surface treatment technology for in-situ growth of a ceramic layer on the surface of an aluminum alloy. Its working principle is to immerse the aluminum alloy workpiece in an alkaline electrolyte (such as a silicate system, pH 11-13), apply a high-voltage pulse power supply of 350-500V (frequency 50-1000Hz), and induce micro-area discharge on the material surface (instantaneous temperature can reach 2000-3000°C). Under the action of plasma electrochemistry / thermodynamic coupling, the aluminum matrix reacts with the electrolyte components to in-situ generate a porous ceramic layer mainly composed of α-Al2O3 (corundum phase, content >60%). The 50-100μm ceramic layer formed by this technology has a unique "three-layer structure" with an outer layer of a porous wear-resistant layer (porosity 15-20%, pore diameter 5-8μm), a middle layer of a dense barrier layer (microhardness >1500HV), and an inner layer of a metallurgical bonding transition layer, so that the crossarm surface can simultaneously achieve three core performance improvements: (1) The corrosion resistance is greatly enhanced, and the salt spray test is greater than 5000 hours without substrate corrosion (8-10 times higher than traditional anodizing); (2) Wear resistance is significantly improved, and the friction coefficient is reduced to 0.15-0.2 (equivalent to twice the life of hard chrome plating); (3) Excellent insulation performance, breakdown voltage > 3000V / μm; in particular, the compressive residual stress (-200 to -400MPa) in the ceramic layer effectively offsets the tensile stress during service, extending the stress corrosion crack initiation time of the crossarm in the strong coastal corrosion environment to more than 15 times that of the traditional process, achieving 30 years of maintenance-free service.

[0027] Preferably, in step 6, ultrasonic flaw detection and infrared thermal imaging technology constitute a dual guarantee system for non-destructive testing of transmission pole crossarms: ultrasonic flaw detection (frequency 2-10MHz) uses a piezoelectric transducer to emit high-frequency sound waves. Based on the reflection / attenuation characteristics of sound waves by internal metal defects (such as pores and inclusions) (a defect is determined when the echo amplitude difference is greater than 6dB), it can detect tiny defects ≥0.5mm with a positioning accuracy of ±0.1mm; infrared thermal imaging utilizes the difference in thermal conductivity caused by delamination of composite materials (the temperature difference between the normal area and the delamination area is greater than 2°C) and captures the dynamic heat flow field with a high-sensitivity infrared camera (resolution <20mK), achieving rapid imaging detection of delamination defects ≥1mm²; these two technologies work together to increase the internal defect detection rate of metal crossarms to 99.9% (false alarm rate <0.1%) and the delamination identification sensitivity of composite crossarms by 10 times, jointly ensuring that the product can serve without hidden dangers under extreme loads.

[0028] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A production process for high-strength, corrosion-resistant transmission pole crossarms, characterized by: The steps include: Step 1: Select SCC-resistant aluminum alloy; add trace amounts of Sc to refine grains and improve corrosion resistance; avoid cold working and adopt warm forming process; Step 2: melting aluminum alloy ingots and hot extrusion molding; Step 3: T6 solution treatment to improve strength; Step 4: Use a five-axis CNC machining center to perform structural topology optimization cutting; the surface roughness of key load-bearing parts is Ra ≤ 0.8μm; ultrasonic-assisted drilling technology is used; Step 5, micro-arc oxidation; Step 6: Ultrasonic flaw detection and infrared thermal imaging.

2. The production process of a high-strength, corrosion-resistant transmission pole crossarm according to claim 1, characterized in that: In step 1, in the production process of transmission pole crossarms, 5083-H116 aluminum alloy, which has excellent resistance to stress corrosion cracking (SCC), is selected to replace the traditional 7075 alloy. This key material significantly improves the environmental adaptability of the product through the following three optimization mechanisms: First, the β phase formed by the magnesium content of the 5083-H116 alloy has more stable electrochemical properties, which fundamentally avoids the sensitivity to intergranular corrosion caused by the copper element in the 7075 alloy. Secondly, adding 0.1-0.3wt% scandium can form Al3Sc nano-precipitates during the solidification process, which not only refines the grain size to 1 / 3 of that of the traditional process, but also shifts the pitting potential positively by more than 200mV through the passivation effect of the Sc-O bond. Finally, a warm forming process at 150-200℃ is used instead of cold working, which not only maintains 60-70% of the cold work hardening effect but also reduces the residual stress to 1 / 5 of the cold working. This thermal and mechanical synergistic regulation increases the stress corrosion threshold value (KISCC) of the product in a C4 level corrosion environment to 35MPa·m1 / 2, nearly three times higher than that of the traditional process.

3. The production process of a high-strength, corrosion-resistant transmission pole crossarm according to claim 1, characterized in that: The SCC-resistant aluminum alloy material in step 1 combined with subsequent micro-arc oxidation treatment can extend the service life of the crossarm in a coastal high-salt fog environment to over 30 years.

4. The production process of a high-strength, corrosion-resistant transmission pole crossarm according to claim 1, characterized in that: In step 2, during the smelting and hot extrusion process of the aluminum alloy ingot for the transmission pole crossarm, the content of Fe and Cu impurity elements is strictly controlled to effectively avoid the formation of coarse intermetallic compounds and significantly improve the purity of the material; During the hot extrusion forming stage, a multi-stage diversion die design and isothermal extrusion technology are used, combined with a stress distribution scheme optimized by finite element simulation, to reduce the metal flow stress during the extrusion process by 15-20%. This not only eliminates the surface cracks and internal shrinkage defects common in traditional processes, but also controls the fluctuation range of the mechanical properties of the cross-arm section to within ±5%.

5. The production process of a high-strength, corrosion-resistant transmission pole crossarm according to claim 1, characterized in that: In step 2, metallurgical purity control and plastic deformation are synergistically optimized to ensure that the product has a uniform fine-grained structure while also having excellent strength and toughness matching, laying an ideal material foundation for subsequent heat treatment and surface treatment.

6. The production process of a high-strength, corrosion-resistant transmission pole crossarm according to claim 1, characterized in that: In step 3, the T6 solution aging heat treatment is a key process for strengthening the aluminum alloy crossarms. The T6 solution aging heat treatment is performed at 530°C ± 5°C to fully dissolve the alloying elements to form a supersaturated solid solution. The alloy is then water quenched to freeze the high-temperature microstructure, and then artificially aged at 175°C for 8 hours to promote the dispersion and precipitation of the GP zone and β" strengthening phase. This treatment increases the tensile strength of the 5083-H116 aluminum alloy from 260 MPa to ≥ 350 MPa while maintaining an elongation of more than 12%. In particular, by precisely controlling the aging parameters to achieve a discontinuous distribution of the precipitated phase at the grain boundaries, the strength is increased while minimizing stress corrosion sensitivity, achieving an optimal balance between strength, plasticity, and corrosion resistance.

7. The production process of a high-strength, corrosion-resistant transmission pole crossarm according to claim 1, characterized in that: In step 4, during the precision machining of the transmission pole crossarm, a five-axis CNC machining center is used to implement structural topology optimization cutting, and a lightweight design driven by finite element analysis is used to increase material utilization by more than 40%, while ensuring that the stress concentration factor is controlled below 1.

5. During the machining process, diamond tools are used for precision milling of key load-bearing parts to achieve ultra-precision surface with Ra≤0.8μm, which increases fatigue life by 2-3 times compared with conventional machining. In particular, ultrasonic-assisted drilling technology is introduced in the processing of connecting holes. The intermittent cutting effect generated by high-frequency vibration reduces the axial cutting force by 35%, the residual stress on the hole wall by 60%, and eliminates burrs, thereby reducing the micro-wear rate in the bolt connection area by more than 50%.

8. The production process of a high-strength, corrosion-resistant transmission pole crossarm according to claim 7, characterized in that: The composite precision machining in step 4 achieves a breakthrough performance improvement of 20% in dynamic load bearing capacity while reducing the weight of the crossarm by 15% through the three-level coordination of "macrostructure optimization - microsurface control - local process enhancement".

9. The production process of a high-strength, corrosion-resistant transmission pole crossarm according to claim 1, characterized in that: In step 5, micro-arc oxidation is an advanced surface treatment technology that grows a ceramic layer in situ on the surface of aluminum alloys. Its working principle is to immerse the aluminum alloy workpiece in an alkaline electrolyte and apply a high-voltage pulse power supply of 350-500V to induce micro-area discharge on the material surface. Under the plasma electrochemical / thermodynamic coupling effect, the aluminum matrix reacts with the electrolyte components to form a porous ceramic layer mainly composed of α-Al2O3 in situ. The 50-100μm ceramic layer formed by this technology has a unique "three-layer structure" with a porous wear-resistant outer layer, a dense barrier layer in the middle, and a metallurgically bonded transition layer in the inner layer, which simultaneously improves the three core properties of the crossarm surface: (1) The corrosion resistance is greatly enhanced, and the salt spray test is greater than 5000 hours without substrate corrosion; (2) Wear resistance is significantly improved, and the friction coefficient is reduced to 0.15-0.2; (3) Excellent insulation performance, breakdown voltage > 3000V / μm; in particular, the compressive residual stress in the ceramic layer effectively offsets the tensile stress during service, extending the stress corrosion crack initiation time of the crossarm in the strong coastal corrosion environment to more than 15 times that of the traditional process, achieving 30 years of maintenance-free service.

10. The production process of a high-strength, corrosion-resistant transmission pole crossarm according to claim 1, characterized in that: In step 6, ultrasonic flaw detection and infrared thermal imaging technology form a dual guarantee system for non-destructive testing of transmission pole crossarms: ultrasonic flaw detection uses piezoelectric transducers to emit high-frequency sound waves. Based on the reflection / attenuation characteristics of sound waves by internal metal defects, it can detect tiny defects ≥0.5mm with a positioning accuracy of ±0.1mm; infrared thermal imaging utilizes the difference in thermal conductivity caused by the delamination of composite materials, and uses a high-sensitivity infrared camera to capture the dynamic heat flow field to achieve rapid imaging detection of delamination defects ≥1mm². These two technologies work together to increase the internal defect detection rate of metal crossarms to 99.9% and the delamination identification sensitivity of composite crossarms by 10 times, jointly ensuring that the product can serve without hidden dangers under extreme loads.

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