Industrial chain systems form the backbone of production lines and power transmission mechanisms. However, the biggest enemy of these systems is a force that works invisibly and silently: corrosion. Nem, kimyasal buharlar, asidik ortamlar ve sıcaklık değişimleri, metal yüzeylerde başlayan korozyon süreci, zamanla zincirin mekanik bütünlüğünü tahrip eder ve beklenmedik arızalara yol açar. Endüstriyel tesislerde zincir kaynaklı arızaların yaklaşık %35’inin temel nedeni korozyon ve paslanmadır.
In this comprehensive guide, we will examine the corrosion mechanism in industrial chains from start to finish, covering every strategy from galvanising techniques to electrolytic coating methods, and from stainless steel alternatives to surface hardening processes. The right corrosion prevention strategy seçiminin, zincir ömrünü 2-5 kat uzatabildiğini ve toplam sahip olma maliyetini %40’a kadar düşürebildiğini gösteren verilerle donatılmış bir kaynak sunuyoruz.
The Corrosion Mechanism in Industrial Chains
Corrosion is the degradation of metal as a result of chemical or electrochemical reactions with environmental factors. In industrial chains, corrosion is not merely an aesthetic issue; corrosion that begins at connecting pins, bearing areas and the inner surfaces of plates dramatically reduces the chain's load-bearing capacity and mechanical strength. Failure analysis in chain and gear systems is carried out, the proportion of cases in which corrosion is identified as the root cause is remarkably high in industrial facilities.
Types of Corrosion and Their Industrial Effects
The main types of corrosion encountered in industrial environments are as follows:
- Uniform corrosion: Corrosion that occurs at a uniform rate across the entire metal surface. It is the most common type and is seen in carbon steel chains used in humid environments. Annual thickness loss ranges from 0.05 to 0.5 mm.
- Galvanic corrosion: Corrosion that occurs in the presence of an electrolyte where two different metals are in contact. It is frequently seen in copper-bronze twist-link chains and connecting elements made of dissimilar alloys.
- Pitting corrosion: A type of corrosion that appears as localised, deep pits. It can occur even in stainless steel chains in the presence of chlorides and is the most dangerous type, as the thickness loss may not be noticeable during visual inspection.
- Stress corrosion: Cracks that form in chain components under tensile stress, combined with a corrosive environment. As it can lead to sudden fractures, it is particularly critical in lift and hoist chains.
- Corrosion fatigue: A damage mechanism arising from the combined effect of cyclic loads and a corrosive environment. It is the most common type of corrosion encountered in conveyor chains.
Corrosion Classification of Industrial Environments
According to the ISO 12944 standard, atmospheric corrosion categories are the primary reference point for industrial chain selection:
C1 – Çok Düşük (Kapalı Kuru Alanlar)
Air-conditioned warehouses, office buildings. Carbon steel chains can be used without protection. Annual corrosion loss: <0.1 μm.
C2 – Düşük (Kırsal Alanlar)
Low-pollution rural areas. Light protection is sufficient. Annual corrosion loss: 0.1-2 μm.
C3 – Orta (Şehir ve Hafif Endüstriyel)
Urban production areas and workshops with light chemical vapours. Chain sprocket material selection becomes critical in this environment. Annual corrosion loss: 2-20 μm.
C4 – Yüksek (Endüstriyel ve Sahil)
Chemical plants, coastal areas, high-humidity environments. Galvanised or stainless steel is required. Annual corrosion loss: 20-50 μm.
C5 – Çok Yüksek (Ağır Endüstriyel)
Environments with dense acid vapours, areas in contact with seawater. Stainless steel or special coating is mandatory. Annual corrosion loss: 50-200 μm.
Galvanised Coating: The First Line of Defence for Industrial Chains
Galvanised coating is the most common and most economical method of corrosion protection for carbon steel chains. The zinc layer provides both barrier protection and works on the principle of cathodic protection. Because zinc is a more active metal than steel, even if the zinc layer is scratched, it continues to protect the steel against corrosion. This mechanism is cathodic protection is what it is called, and it is the greatest advantage of galvanised coating.
Hot-Dip Galvanising (Hot-Dip Galvanizing)
Hot-dip galvanising is the most widely used coating method for industrial chains. In accordance with the ISO 1461 standard , in this process, cleaned steel chains are immersed in a molten zinc bath at a temperature of approximately 450°C. The iron-zinc alloy layers that form between the steel surface and the zinc interlock through a chemical bond, thereby providing protection that is resistant to mechanical impact.
Hot-dip galvanising process steps:
- Degreasing: Removal of organic oils and dirt in an alkaline bath (50-60°C, 5-10 minutes)
- Rust and scale removal: Dissolving oxide layers in an HCl or H2SO4 bath (ambient temperature, 10-20 minutes)
- Rinsing: Removal of acid residues with water
- Fluxing: Immersion in an ammonium chloride solution to facilitate wetting in the zinc bath
- Drying: Moisture removal in a 100-120°C oven
- Galvanising bath: Immersion in molten zinc at 440-460°C (3-8 minutes, depending on thickness)
- Cooling: Controlled cooling with air or water
Hot-dip galvanised coating thicknesses are standardised according to steel thickness:
- Steel below 1.5 mm: minimum 45 μm zinc coating
- Steel 1.5-3 mm: minimum 55 μm zinc coating
- Steel 3-6 mm: minimum 70 μm zinc coating
- Steel above 6 mm: minimum 85 μm zinc coating
Advantages of Hot-Dip Galvanising
- Cathodic protection: Continues to protect the steel even in scratched and damaged areas
- Complete surface coverage: Full protection, including internal surfaces, holes and hard-to-reach areas
- Long service life: 20-40 years of protection in a C3 environment, 10-25 years in a C4 environment
- Cost-effective: 30-50% lower life-cycle cost compared to paint systems
- Maintenance-free: Requires no renewal for the first 15-20 years
Limitations of Hot-Dip Galvanising
- Size limitation: Galvaniz banyosu boyutlarıyla sınırlıdır (Türkiye’de maksimum ~12 m banyolar mevcut)
- Inconsistent zinc coating thickness: Thickness control can be difficult on thin-walled parts
- High-temperature effect: The 450°C process temperature can affect the mechanical properties of some heat-treated steels
- Aesthetics: Does not provide a flawless finish for applications requiring a bright, smooth surface
- Post-weld voids: Zinc vaporisation at welded joints can cause problems
Electrolytic Galvanising (Electrogalvanising)
In the electrolytic galvanising method, zinc ions are deposited onto the steel surface with the aid of an electric current. Being a cold process, it is suitable for parts affected by heat treatment. However, the coating thickness is much lower than with hot-dip galvanising (5-25 μm), and the duration of cathodic protection is limited.
Electrolytic galvanised coating thicknesses and expected protection periods:
- 5 μm (Fe/Zn5): Very low protection, suitable only for C1 environments, 1–2 years
- 8 μm (Fe/Zn8): Low protection, 2–5 years in C2 environments
- 12 μm (Fe/Zn12): Medium protection, 5–8 years in C3 environments
- 25 μm (Fe/Zn25): Good protection, 8–12 years in C4 environments
Stainless Steel Chain Alternatives
In severe environments where galvanised coating alone cannot provide sufficient corrosion protection, stainless steel chains become an essential option. Thanks to its chromium content, stainless steel protects itself by forming a thin, continuously self-renewing passive oxide layer on its surface. When this layer is damaged, it repairs itself rapidly in the presence of oxygen.
Stainless Steel Grades and Application Areas
AISI 304 Stainless Steel Chains
This is the most common type of stainless steel. With 18% chromium and 8% nickel content, it offers good corrosion resistance. It is ideal for the food industry, pharmaceutical production, mild chemical environments and indoor applications. However, there is a risk of pitting corrosion in chloride environments.
- Chemical composition: 18% Cr, 8% Ni, max 0.08% C
- Tensile strength: 515–620 MPa
- Corrosion resistance: Suitable up to C4 environments, chlorides should be avoided
- Cost: 3–4 times higher than carbon steel
AISI 316 Stainless Steel Chains
This grade has enhanced resistance to chloride corrosion through the addition of molybdenum (2–3%). It is the most suitable stainless steel grade for marine environments, chemical plants, heavy industry and outdoor applications. NACE International standards, it is the only stainless steel grade suitable for use in marine environments.
- Chemical composition: 16–18% Cr, 10–14% Ni, 2–3% Mo, max 0.08% C
- Tensile strength: 515–620 MPa
- Corrosion resistance: Suitable up to C5 environments, high chloride resistance
- Cost: 4–5 times higher than carbon steel
AISI 316L and Special Stainless Steels
Low-carbon (0.03% max C) 316L eliminates the risk of corrosion in the heat-affected zone after welding. Duplex stainless steels (2205, 2507) combine austenitic and ferritic structures to provide both high strength and superior corrosion resistance. Super duplex 2507 can be used safely even in the most severe corrosive environments.
Surface Coating and Hardening Methods
In addition to galvanising and stainless steel, various surface treatments are applied to industrial chains for corrosion and wear protection. These methods are selected according to specific application requirements and are often used in combination.
Nickel Plating
Nickel plating is used for both decorative and functional purposes. An electrolytically applied nickel layer (10–30 μm) provides good corrosion resistance and a hard surface. However, nickel plating is sensitive to scratches, and the underlying steel is not protected against corrosion. It is generally used as an underlayer for chrome plating.
Chrome Plating (Hard Chrome)
Hard chrome plating is applied at a thickness of 50-500 μm and provides a surface hardness of 900-1100 HV. Chain lubrication systems, when used in combination with these, both wear and corrosion resistance are maximised. It is preferred in hydraulic cylinders, conveyor chain pins and applications requiring high wear resistance.
Ceramic and PVD Coatings
Ceramic coatings applied by the physical vapour deposition (PVD) method are among the most innovative corrosion prevention technologies of recent years. TiN (titanium nitride), TiAlN (titanium aluminium nitride) and DLC (diamond-like carbon) coatings offer outstanding wear resistance with hardness values of 2000-3500 HV, while their chemical stability forms an excellent barrier against corrosion.
- TiN coating: Gold colour, 2300 HV hardness, widely used in chains for the food and textile industries
- TiAlN coating: Purple-black colour, 3200 HV hardness, high-temperature applications
- DLC coating: Black colour, 3500 HV hardness, low coefficient of friction, preferred for automotive chains
Polymer and Rubber Coatings
In conveyor chains used particularly in the food industry, polyurethane and epoxy coatings are applied to provide corrosion protection and hygiene. These coatings fully isolate the metal surface, preventing chemical contact. However, they offer limited resistance to mechanical wear and must be renewed at regular intervals.
Corrosion Prevention Strategies: Decision Matrix
Choosing the right corrosion prevention strategy requires evaluating environmental conditions, cost targets and expected service life together. The decision matrix below helps determine the most suitable strategy for different scenarios:
Strategies for Low Corrosion Environments (C1-C2)
- Short term (1-3 years): Oiled carbon steel + periodic lubrication
- Medium term (3-10 years): Phosphate coating + oil, electrolytic galvanising
- Long term (10+ years): Hot-dip galvanising, AISI 304 stainless
Strategies for Medium-High Corrosion Environments (C3-C4)
- Short term (1-3 years): Electrolytic galvanising (Fe/Zn25), phosphate + oil
- Medium term (3-10 years): Hot-dip galvanising, duplex coating (galvanising + paint)
- Long term (10+ years): AISI 316 stainless, duplex stainless steel
Strategies for Very High Corrosion Environments (C5-CX)
- Short term (1-3 years): Hot-dip galvanising + epoxy paint
- Medium term (3-10 years): AISI 316 stainless, duplex galvanising + polyurethane paint
- Long term (10+ years): Super duplex 2507, Hastelloy, titanium chain
Maintenance and Inspection: The Ongoing Front of Corrosion Control
Corrosion prevention is not limited to selecting the right material and coating alone. Proactive maintenance and regular inspection are the most important factors determining the effectiveness of any corrosion prevention strategy. Corrosion damage detected at an early stage through routine inspections can be resolved before it develops into major failures.
Periodic Inspection Programme
Corrosion inspection of industrial chains should be carried out at different intervals depending on the C class:
- C1-C2 environments: Annual visual inspection, thickness measurement every 3 years
- C3 environments: Six-monthly visual inspection, annual thickness measurement
- C4-C5 environments: Quarterly visual inspection, six-monthly thickness measurement and ultrasonic testing
Key Points to Consider During Inspection
- Pin-connection areas: These are the areas where corrosion damage most commonly starts. Oxide build-up and increased friction should be checked at bearing pin areas.
- Inner plate surfaces: Corrosion starting on the contact surfaces of connecting plates leads to thickness loss and reduced strength.
- Welded joints: Corrosion resistance is reduced in heat-affected zones. Weld seams and bolted joints should be inspected particularly closely.
- Galvanised coating integrity: Galvanised chains should be checked for the formation of white rust (zinc oxide) and red rust (iron oxide).
- Stress and fatigue marks: Stress cracks combined with corrosion can be difficult to detect through visual inspection. Magnetic particle testing is recommended.
Corrosion Prevention Recommendations by Industrial Sector
Food and Pharmaceutical Sector
In food production, hygiene and corrosion prevention go hand in hand. AISI 316L stainless steel chains are preferred in compliance with food safety regulations. These chains must withstand cleaning chemicals (sodium hypochlorite, nitric acid), and regular CIP (Cleaning-In-Place) procedures increase the risk of corrosion. For this reason, choosing stainless steel is essential, and galvanised chains should not be used in the food sector.
Automotive and Transport
Chains used in vehicles must withstand salted road conditions and exposure to oils and chemicals. Hot-dip galvanising is the standard protection method for automotive chains. In applications requiring higher performance, nickel + chrome composite coating is preferred.
Marine and Port Sector
The marine environment (C5-CX) presents the most demanding conditions for corrosion, combining salt water spray, high humidity and temperature fluctuations. AISI 316 stainless steel is the minimum requirement; for longer service life, super duplex stainless steel or duplex coating systems (galvanising + epoxy + polyurethane paint) are recommended.
Mining and Heavy Industry
In mines, acidic water, abrasive dust and heavy loads occur together. Galvanised chains provide basic protection, but their service life is limited in acidic environments. Special coatings (ceramic, PVD) or high-carbon galvanised chains should be preferred.
Conclusion: Multiplying Chain Life with the Right Strategy
Corrosion and rust prevention in industrial chains cannot be achieved with a single solution, but through a range of strategies tailored to environmental conditions. Galvanised coating stands out as a cost-effective and reliable first line of defence, while stainless steel and special coatings become essential in heavily corrosive environments. Gurur Makina olarak, 1986’dan beri transmisyon zincirleri sektöründe edindiğimiz deneyimle, projelerinizin gereksinimlerine en uygun korozyon önleme stratejisini belirlemenize yardımcı oluyoruz.
Ignoring corrosion resistance when choosing your chain leads to nothing but a higher total cost of ownership. With the right material, the right coating and the right maintenance programme, you can multiply the service life of your industrial chains. From conveyor chains to transmission chains, and from motorcycle chains to custom-manufactured chains, we are here to offer solutions tailored to your needs with our wide product range. For detailed information and project consultancy, our contact page you can reach us through it.