Corrosion Resistant Yoke Plates are core structural connectors in power transmission and distribution, rail transportation, new energy wind power, offshore infrastructure, and heavy chemical industries. They are primarily used for insulator string connections, conductor tension transmission, and steel structure node fixing. These plates are exposed to various corrosive environments, including outdoor atmospheres, coastal salt spray, industrial acids and alkalis, soil salinity, and humid and hot conditions. Their corrosion resistance directly determines the product's service life, operational safety, and overall project maintenance costs.
The substrate is the foundation of the Corrosion Resistant Yoke Plate's corrosion protection. High-quality corrosion-resistant substrates possess excellent corrosion resistance, significantly reducing the burden of subsequent surface treatment and achieving dual corrosion protection through a "substrate + surface layer." During production, the appropriate substrate material must be precisely selected based on the product's operating environment, load-bearing capacity, and cost budget. This establishes a strong first line of defense against corrosion from the raw material entry stage, which is the most fundamental and long-lasting method of corrosion protection.
Carbon structural steel is currently the most commonly used base material for producing conventional corrosion resistant yoke plates. It offers controllable cost, excellent mechanical properties, and easy processing. By optimizing the material grade and internal composition, the corrosion resistance of the base can be improved, making it suitable for inland conventional outdoor and non-corrosive industrial environments. Using Q355NHD and Q355NH weathering steel, with trace amounts of copper, chromium, nickel, phosphorus, and other alloying elements added, a dense and continuous passivation protective film can be formed on the surface of the base material. This effectively blocks the penetration of corrosive media such as oxygen, moisture, and sulfur dioxide in the air, resulting in atmospheric corrosion resistance 2-3 times that of ordinary Q235 steel. This makes it suitable for yoke plate production in inland areas and lightly polluted industrial environments. Material certificates must be checked when raw materials enter the factory, and the content of alloy elements must be tested by a spectrometer to ensure that corrosion-resistant elements such as copper, chromium, and phosphorus meet the standards. It is strictly forbidden to use inferior steel smelted from recycled scrap steel to avoid excessive internal impurities and loose intergranular structures, which accelerate corrosion. Plasma cutting or laser cutting is used for blank cutting instead of traditional flame cutting to reduce the thickness of oxide scale on the cut surface and reduce the difficulty of subsequent rust removal.
Corrosion resistant yoke plates generate significant internal stress during the casting, forging, welding, and machining processes of the blank. This internal stress can lead to product deformation and, in corrosive environments, stress corrosion cracking-a corrosion hazard easily overlooked in production. Hot forging is employed, controlling the forging temperature between 850-1100℃ to ensure a dense base material free of defects such as porosity, shrinkage cavities, and cracks. Slow cooling after forging avoids rapid cooling and the generation of internal stress. The dense microstructure effectively blocks the penetration of corrosive media, reducing corrosion pathways at the blank level. Precision sand casting is used during ductile iron casting, controlling the pouring temperature and cooling rate to minimize casting porosity, sand holes, and slag inclusions. Shot blasting is performed after casting to remove surface oxide scale and adhering sand, laying a solid foundation for subsequent surface anti-corrosion treatment.
Machining is a crucial step in the forming of Corrosion Resistant Yoke Plates. The roughness, smoothness, burrs, and scratches of the machined surface directly affect the adhesion and integrity of the subsequent anti-corrosion layer. A rough surface can lead to uneven thickness and localized peeling of the anti-corrosion layer, while corrosive media can easily accumulate in gaps and burrs, causing crevice corrosion and pitting. Therefore, the core of corrosion prevention in the machining process is to strictly control surface quality and create a flat, smooth, and defect-free machining base. After machining, pneumatic grinding, ultrasonic cleaning, and high-pressure water washing are used to thoroughly clean the workpiece surface of iron filings, oil, cutting fluid, and burrs. Edges and corners are rounded and chamfered to avoid sharp edges that could cause uneven accumulation of the anti-corrosion layer and easy detachment due to impacts. Residual cutting fluid on the workpiece surface is strictly prohibited, as the chemical components in the cutting fluid can corrode the substrate; therefore, degreasing treatment is performed promptly after machining.
Surface treatment is the most crucial and direct anti-corrosion method in the production of Corrosion Resistant Yoke Plates. By covering the substrate surface with a dense, highly adhesive, and corrosion-resistant protective layer, it completely isolates the substrate from corrosive media. Different surface treatment processes are employed during production, depending on the product application, cost requirements, and corrosion protection lifespan. These processes are categorized into three main types: conventional anti-corrosion, reinforced anti-corrosion, and special anti-corrosion. Each process has strict production operation specifications.
Hot-dip galvanizing anti-corrosion: This is currently the most commonly used surface anti-corrosion process for producing corrosion-resistant yoke plates both domestically and internationally. It is suitable for carbon steel and low-alloy steel substrates, offering good anti-corrosion performance, moderate cost, and long service life. It is widely used in inland and mildly corrosive environments.
Hot-dip galvanizing + sealing coating composite anti-corrosion: Targeting moderately corrosive environments such as coastal areas, near-shore areas, moderate industrial pollution, and humid and rainy conditions, this method adds a sealing coating to the hot-dip galvanizing process, forming a dual composite protection of "zinc layer + organic sealing layer." This significantly extends the corrosion protection lifespan and is a commonly used reinforced anti-corrosion solution for export yoke plates.
Zinc-aluminum coating for corrosion protection: Suitable for yoke plates made of high-strength steel and welded structures. It avoids hydrogen embrittlement cracking caused by pickling, and its corrosion resistance far exceeds that of ordinary hot-dip galvanizing. It meets EU environmental standards and is suitable for export to Europe, America, Japan, South Korea, and other regions with stringent environmental requirements.
Stainless steel pickling and passivation corrosion protection: For corrosion-resistant yoke plates made of 304, 316, and 2205 stainless steel, pickling and passivation is the core surface corrosion protection process. No additional coating is required; corrosion protection is achieved by restoring and strengthening the stainless steel's own passivation film. This is a long-lasting, maintenance-free corrosion protection solution.
