Stainless Steel, Aluminum, And PC/ABS - The Real-world Performance And Applicable Scenarios of These Three Materials in Salt Spray Environments.

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If you are an electrical engineer or purchasing manager on an EPC project and are selecting enclosure materials for a coastal or chemical project, this article will help you figure it out:

1. Real-world corrosion resistance of stainless steel, aluminum, and PC/ABS plastics in salt spray environments.

2. Advantages, disadvantages and applicable scenarios of the three materials

3. Quickly pinpoint material orientation based on corrosion level.

This article is byBSUMWELLWritten by our technical team, we are a manufacturer and wholesaler specializing in waterproof electrical enclosures. Our products cover three major material series: stainless steel, aluminum, and PC/ABS plastic, with protection levels ranging from IP67 to IP68. We support OEM/ODM customization.

Overview of the corrosion resistance of the three main materials

In coastal or chemical projects, the choice of casing material determines how long the equipment can withstand the load.

In the previous article in this series, we clarified the underlying logic that "IP rating does not equal corrosion resistance." Since IP rating doesn't solve the corrosion resistance problem, what truly determines corrosion resistance?

It's the material itself.

Below, we use a table to quickly compare the overall performance of the three materials in a salt spray environment:

(Note: The corrosion resistance rating is an industry-standard assessment based on ISO 9223 corrosion rating and ASTM B117 salt spray test data. Actual performance may vary depending on product material, coating quality, and installation environment.)

In short:

• Stainless steel: The strongest corrosion resistance and longest lifespan, suitable for highly corrosive environments—the standard answer for coastal and offshore projects.

• Aluminum casing: Lightweight design and excellent heat dissipation make it suitable for moderately corrosive environments—a cost-effective choice for industrial areas and offshore projects.

• PC/ABS plastic: Zero corrosion + lowest cost, suitable for low-corrosion environments – an economical choice for inland and general outdoor projects.

Our product line covers three major material series: stainless steel, aluminum, and PC/ABS plastic—whether your project is in the C1 or CX corrosion rating range, there is a corresponding material option. OEM/ODM customization is supported.

Stainless steel casing selection for coastal and highly corrosive environments – 304 or 316?

Why is stainless steel corrosion resistant?

Stainless steel's corrosion resistance comes from...Chromium。

Stainless steel contains at least 10.5% chromium. Chromium reacts with oxygen in the air to form an extremely thin, dense, and transparent chromium oxide passivation film (Cr₂O₃) on the surface of the steel. This film is only a few nanometers thick, but it is very stable—it prevents oxygen atoms from penetrating further into the steel, thus blocking the chemical reaction that causes corrosion.

For example - This passivation film acts like an "invisible armor" for the steel. As long as this armor is not damaged, corrosion will not occur.

Different grades of stainless steel have vastly different corrosion resistance. The core difference lies in the ratio of alloying elements.

304 Stainless Steel vs. 316 Stainless Steel – The "Watershed" in Corrosion Resistance

The table below clearly compares the key differences between the two types of stainless steel:

(The above chemical composition and performance differences are based on ASTM A240/A240M standards, which specify the chemical composition and mechanical property requirements for stainless steel sheets.)

Application scenarios of stainless steel

Limitations of stainless steel

• Highest initial cost: The procurement cost of 316 stainless steel is typically 3-5 times that of PC/ABS plastic.

• Heavy: Additional reinforcement is required for the mounting bracket.

• Grounding is required: Stainless steel is a conductor and must be reliably grounded.

With proper selection (316 for C5/CX environments) and installation conditions, stainless steel enclosures can achieve... Over 20 years of maintenance-free operation — Based on the self-healing properties of the passivation film of stainless steel and the data of 316 stainless steel showing no red rust after 1000+ hours of salt spray testing in ASTM B117.

Procurement Reminder

Material certification (MTC) is required.

MTC (Mill Test Certificate) is the "identity card" for stainless steel, recording the material's chemical composition and mechanical properties. When purchasing, request the supplier to provide the MTC to ensure you receive genuine 316, not "nominal 316, actual 304".

We offer a range of stainless steel enclosures, with materials selectable based on the project's corrosion tolerance (304 or 316). Material certification (MTC) is available. IP67-IP68 protection ratings are supported. Learn about stainless steel casing series

Corrosion protection selection for aluminum casings in salt spray environments – the trade-off for lightweight design is coating protection.

The Corrosion Prevention Logic of Aluminum

Aluminum itself is a metal that is "self-corroding".

Aluminum reacts with oxygen in the air to form a thin film of natural aluminum oxide (Al₂O₃) on its surface. This film is thicker than the passivation film of stainless steel and is sufficient to protect aluminum from corrosion under normal conditions.

The problem is that chloride ions in a salt spray environment can attack this natural oxide film.

In coastal salt spray environments, chloride ions can penetrate tiny defects in the natural oxide film and reach the surface of the aluminum substrate, triggering an electrochemical reaction that causes the aluminum to begin "pitting corrosion" from the surface.

Plain understanding: In normal environments, aluminum can be protected by its own rust-proof layer, but in coastal salt spray environments, this rust-proof layer is not thick enough.

What protects the aluminum casing from salt spray? — Coating protection

Core LogicThe premise that aluminum casing can be used in coastal environments is...High-quality coating protectionThe corrosion resistance of aluminum depends not on the aluminum itself, but on the quality of the coating system.

Standard configuration:

• Substrate: Marine-grade aluminum alloy (typically 6061 or 5052 series)

• Coating thickness: 80-120μm polyester powder coating

• Coating process: Degreasing → Phosphating/Chromating → Primer → Topcoat → Baking and Curing

⚠️ Key risk: Coating damage

If the coating is scratched during transportation or installation, the damaged aluminum substrate will be directly exposed to salt spray—pitting corrosion will start from the scratch and spread to the surrounding area, causing large areas of coating to peel off.

Advantages and disadvantages of aluminum casing

• Advantages:

• Lightweight: Weighing only 1/3 of stainless steel – suitable for projects with limited support capacity.

• Excellent heat dissipation performance: Its thermal conductivity is more than 5 times that of stainless steel—making it suitable for applications with internal heat-generating components such as inverters and power supplies.

• Moderate cost: Between stainless steel and PC/ABS

• Disadvantages:

• Corrosion resistance Highly dependent on coating quality — Once the coating is damaged, pitting corrosion will occur rapidly.

• Installation requires caution — Scratches are the leading cause of aluminum casing failure in coastal environments.

• Electrochemical corrosion risk — When aluminum comes into direct contact with stainless steel and is present in the presence of salt spray, aluminum will act as a sacrificial anode, accelerating corrosion.

Application scenarios for aluminum casing

Procurement Reminder

The corrosion resistance of aluminum casings is "bought"— if you buy a good coating, it can resist salt spray; if the coating quality is poor, it's a "time bomb."

When making a purchase, you need to confirm with the supplier:

1. What are the coating type and thickness?

2. Does the coating meet marine environmental standards?

We offer an aluminum housing series with a standard marine-grade polyester powder coating, suitable for C3-C4 corrosion environments. OEM/ODM customization is supported (specifying coating color and thickness). Learn about aluminum casing series

PC/ABS plastic casings are a viable corrosion protection option in coastal and chemical environments—zero corrosion, but with an "invisible enemy."

Corrosion protection logic for PC/ABS plastics

Plastic is rust-free and corrosion-free—this is its core advantage.

PC (polycarbonate) and ABS (acrylonitrile-butadiene-styrene copolymer) are both high-molecular organic materials that do not contain metal elements, so they do not "rust".

When it comes to corrosion resistance, PC/ABS plastic is a "natural winner":

• Absolute zero corrosion: Salt spray has no chemical attack effect on plastics.

• Lightest weight: Lighter than aluminum, with the lowest required support load capacity.

• Excellent insulation properties: No grounding is required, saving installation time.

• Lowest cost: The initial procurement cost is approximately 1/5 to 1/3 of that of stainless steel.

• Flexible molding: Injection molding can manufacture complex structures, and the cost of mold making is relatively controllable.

The "invisible enemy" of plastics: two easily overlooked failure modes

Plastics have an inherent advantage in corrosion resistance, but there are two "invisible enemies" that need to be guarded against in certain environments.

Enemy 1: UV aging

• Performance: Ordinary PC/ABS will yellow and become brittle after 3-5 years under direct outdoor sunlight.

• Solution: Using a UV-resistant formula with added UV stabilizers can extend the outdoor lifespan to 10-15 years.

• Identification techniques: UV-resistant materials are slightly milky white, while ordinary materials are more transparent. When purchasing, you can ask, "Are you sure this is UV-resistant?"

Enemy Two: Environmental Stress Cracking (ESC)

• Mechanism: Installation stress (screw tightening force) + organic solvent vapor (acetone/benzene) combined → unexpected brittle cracking at the stress point

• Typical scenarios: The chemical plant's air contains a small amount of organic solvent vapor + the screws on the outer cover plate are tightened properly → after a period of operation, cracks appear around the screw holes.

• Solution: Confirm the material's tolerance to organic solvents in the project environment; optimize installation torque to avoid over-tightening; for environments with high concentrations of organic solvents, it is recommended to replace with stainless steel.

Application scenarios of PC/ABS plastic

Procurement Reminder

When choosing a PC/ABS plastic casing, the key is to look at two "additions": Is a UV stabilizer added? Can a chemical compatibility assessment be provided?

We offer a range of PC/ABS plastic housings with UV-resistant formulations suitable for environments with corrosion ratings of C1-C3. For chemical plant projects, we can provide chemical compatibility assessment advice. Learn about PC/ABS plastic housing series

Quick Selection Table by Project Type

How do I use this table?

1. Please confirm your project type (coastal/industrial zone/inland/chemical plant, etc.).

2. Find the corresponding recommended material in the table.

3. Check if there are any additional notes in the Special Requirements section.

4. For special customization, please contact customer service to confirm the replacement solution.

(The above selections are general suggestions only. For support in selecting corrosion-resistant materials for specific projects, please contact our technical team—we can provide a free selection assessment based on ISO 9223 corrosion levels and project requirements, typically offering preliminary advice within 24 hours. ) Contact the technical team for a free selection assessment.)

Summary of the key points of this article

1. Stainless steel is the "preferred choice" for coastal and offshore environments. — 316 contains molybdenum, and its resistance to chloride ion corrosion is far superior to that of 304. Under proper selection (316 is selected for C5/CX environments) and installation conditions, it can achieve more than 20 years of maintenance-free operation.

2. The corrosion resistance of an aluminum casing depends on the quality of the coating. — Once the coating is damaged, pitting will occur rapidly.

3. PC/ABS plastic is a zero-corrosion material.— However, be wary of UV aging and stress cracking (ESC) in chemical environments.

4. The selection logic is "Scene → Material".— C5/CX → Stainless steel, C3-C4 → Aluminum, C1-C3 → PC/ABS plastic.

5. Pay attention to the material of the components when purchasing.— Once you choose the right casing, the fasteners must also be up to par.

Previous article: Have you grasped the underlying logic of corrosion protection selection and the understanding that IP ≠ corrosion protection? Please read the first article in this series.Lesson One in Corrosion Protection Selection: IP Rating Doesn't Equal Corrosion Protection – How Should Electrical Enclosures Be Selected for Coastal Projects?

Next episode preview: Have you chosen your material? Next, let's learn about ISO 9223 corrosion ratings and system-level corrosion protection solutions—fasteners, sealing strips, and electrochemical corrosion. Please read the third article in this series, "From ISO 9223 Corrosion Ratings to System-Level Corrosion Protection—A Complete Analysis of Electrical Enclosure Selection for Coastal Projects."