As a Chinese custom metal parts manufacturer in China established in 1997, we have over two decades of experience in stamping, drawing, welding, laser cutting, and sheet metal processing. We have also developed strategies for addressing metal corrosion, a common form of corrosion that can lead to serious consequences during production. Rust, a common form of corrosion, not only affects the appearance of parts but also significantly impairs their performance and shortens their service life. Today, drawing on years of industry experience, we provide a detailed analysis of metal rust, focusing on the types of metals susceptible to corrosion, the causes of rust, its hazards, prevention, and remedial measures, to help more businesses and individuals effectively address the challenges of metal corrosion.

Types of Metals Susceptible to Corrosion

In the metalworking industry, the corrosion resistance of different metals varies significantly. The following are some common types of metals susceptible to corrosion in our business:

· Iron and its alloys:Common carbon steel, for example, is a typical metal susceptible to rust. In routine stamping and sheet metal processing, carbon steel is exposed to air and reacts quickly with oxygen and moisture in the air, gradually forming rust on the surface, impacting the subsequent processing and use of the part. Corrosion is particularly severe in summer or during rainy seasons.

· Aluminum and its alloys: Although a thin oxide film naturally forms in the air, providing some temporary protection, this film is easily destroyed in humid and acidic environments, leading to corrosion on aluminum parts. This is especially true after stretching and welding processes. If improper protection is not provided, corrosion problems are more pronounced.

·Copper and its alloys: While relatively corrosion-resistant, they can develop a green patina on the surface in high humidity and sulfur dioxide-containing environments. This not only affects the part's appearance but also its electrical and thermal conductivity, posing a quality risk to precision copper parts after laser cutting.

 Causes of Metal Rust

Metal rust is the result of a combination of internal and external factors. Based on our production experience, the specific causes are as follows:

(I) Internal Factors

· Chemical Composition: The chemical composition of a metal determines its rust resistance. For example, pure iron is more susceptible to rust than iron alloys with added elements such as chromium and nickel. In our custom metal parts, carbon steel exhibits varying rust resistance depending on its carbon content. Higher carbon content generally indicates a higher rust susceptibility. · Structural defects: Cracks, inclusions, and other defects in metal structures can become the starting points for rust. Improper process control during stamping and stretching can easily lead to microcracks in metal parts. During subsequent use, moisture and oxygen can easily penetrate these cracks, accelerating rust.

(II) External Factors

· Humidity: The higher the humidity, the more susceptible the metal is to rust. Moisture is a key medium for chemical reactions during rusting, and the rate of rusting accelerates significantly during the rainy season.

· Oxygen: The oxidation reaction between metal and oxygen is the primary chemical reaction that causes rust. Whether during part processing or during storage and use of finished products, as long as the metal is in contact with air, it will continuously react with oxygen, creating conditions for rust.

· Harmful substances: Harmful substances in the environment, such as sulfur dioxide, carbon dioxide, and salt spray, can accelerate metal rust. For example, customers in coastal areas have reported that metal parts we deliver are more susceptible to rust in high-salt air environments than in inland areas. III. Harms of Metal Rust

Metal rust has a significant impact on industrial production and the use of metal parts. Based on our client cases, the main hazards include:

· Reduced Mechanical Properties: Rust causes the metal surface to become rough, damages the internal structure, and significantly reduces strength, hardness, and toughness.

· Impact on Precision and Performance: For precision stamped and laser-cut parts, rust increases friction between parts, affects motion accuracy, and reduces overall equipment performance.

· Increased Maintenance Costs: Rusted parts require repair or replacement, which consumes time and manpower, increasing costs for the company.

· Environmental Pollution: Rust debris can pollute the production and surrounding environment. The waste liquids and gases generated during rust removal, if not properly handled, can also harm the environment and fail to meet environmentally friendly production requirements.

Preventative Measures for Metal Rust

Based on over 20 years of metal processing experience, we have summarized the following practical metal rust prevention measures to effectively protect metal parts:

· Surface Coating: This is the most common and effective method, isolating the metal from air and moisture. Depending on customer requirements and application scenarios, options include painting, plastic spraying, galvanizing, hot-dip galvanizing, and chrome plating. In our production, sheet metal parts destined for long-term outdoor use are hot-dip galvanized, resulting in a zinc coating with excellent corrosion resistance. Stamped parts requiring a high aesthetic quality receive electroplating with chrome, providing both aesthetic appeal and rust resistance.

· Alloying: The addition of specific alloying elements to metals enhances rust resistance. For example, stainless steel is created by adding chromium, nickel, and other elements to iron. We produce stainless steel stampings and drawn parts based on customer needs. These parts exhibit significantly better rust resistance than ordinary carbon steel parts in humid and corrosive environments.

· Environmental Control: The humidity, temperature, and hazardous material content of metal parts are controlled during use and storage. Our warehouses are equipped with dehumidifiers to maintain optimal humidity levels. Furthermore, metal parts are protected from mixing with materials containing harmful substances such as sulfur dioxide and salt spray to reduce the risk of rust.

· Regular Maintenance: Metal parts are regularly cleaned and inspected to remove surface dust and dirt and to check for signs of rust. We remind our customers to regularly maintain and repair any minor rust that is found to prevent further rust. 

Remedial Measures for Metal Rust

If rust has already occurred on metal parts, targeted remedial measures should be taken based on the severity of the rust to minimize damage:

•Minor Rust: Use mechanical rust removal. Use sandpaper, a wire brush, a grinding wheel, or other tools to gently polish the rusted surface until the shiny metal surface is exposed. After polishing, clean the surface of oil and dust, then apply a layer of anti-rust paint or oil to form a protective coating to prevent further rust. We often use this method to treat slightly rusted parts during after-sales maintenance.

•Moderate Rust: Use chemical rust removal. Either an acidic rust remover (such as hydrochloric acid or diluted sulfuric acid) or an alkaline rust remover can be used. Strictly follow the operating procedures and take personal protective measures to avoid damage to skin and the metal surface caused by the rust remover. After rust removal, rinse the metal surface with clean water to remove any residual rust remover, then perform a passivation treatment to improve the part's rust resistance. 

Severe Rust: If metal parts are severely damaged, their structural strength has significantly decreased, and rust removal and repair are impossible, they require prompt replacement to prevent failure that could impact equipment operation and even cause a safety incident. We can quickly customize replacement parts to ensure smooth production.

In short, metal rust is a common yet potentially detrimental problem in metal processing and use. Kailai Machinery, a small-scale custom metal parts manufacturer with over 20 years of experience, hopes this article will help businesses and individuals gain a deeper understanding of metal rust, effectively prevent rust on metal parts, extend their service life, and minimize financial losses. If you have any questions regarding metal stamping, drawing, welding, laser cutting, sheet metal processing, or metal rust prevention, please contact us. We will leverage our expertise to provide you with high-quality solutions and services.