Does Stainless Steel Rust?
Stainless steel is called stainless because of its resistance to corrosion and rust. Does stainless steel rust? Yes, but at a vastly slower rate than other metals. This resilience makes stainless steel an enormously popular choice for a wide range of manufacturing processes and applications. Rust can cause immense delays to your work, increase costs and damage expensive machinery beyond repair. Understanding why stainless steel resists rust and how to avoid excessive rust can be useful assets when considering how and when to use stainless steel.
Stainless steel: the basics
Before considering the relationship between stainless steel and rust, it’s helpful to understand what stainless steel is. ‘Stainless steel’ refers to a group of iron alloys containing at least 10.5% chromium. There are over 150 different grades of stainless steel, all of which offer a unique combination of corrosion resistance and strength. Chromium is key to stainless steel’s improved corrosion resistance and strength.
Why does stainless steel rust slowly?
Chromium is stainless steel’s weapon against rust. When exposed to the surrounding oxygen, the chromium within stainless steel creates a thin layer of chromium oxide surrounding the metal piece. Unlike iron oxide, which forms flaky and corrosive rust, chromium oxide clings to the steel and acts as a barrier. This barrier separates the steel’s iron content from water and oxygen in the air. This reaction gives stainless steel components resistance in corrosive environments, the passive layer giving them a huge advantage over normal steel.
Factors which affect stainless steel rust
The ability of stainless steel to resist rust depends upon certain conditions. One of the most important is the composition of the stainless steel. Austenitic stainless steels are particularly corrosion-resistant. For example, grade 304 stainless steel is a type of austenitic stainless steel with high rust resistance, making it ideal for catering equipment. Grade 316 stainless steel is more expensive but even more resistant. This steel has exceptional corrosion resistance because of the addition of molybdenum to the alloy, particularly against chlorides and industrial solvents. That addition means this grade is commonly chosen for stainless steel products like surgical instruments and industrial components, such as bolts and nuts.
The surrounding environment can also affect corrosion. Substances like seawater and chlorine create a corrosive environment, accelerating the rusting process of stainless steel components. In particular, chlorine can cause pitting corrosion, where rust bores cavities in the steel piece. For brittle normal steel, this can quickly damage metal pieces beyond repair. If you know your steel will be used in corrosive environments like seawater, you should consider using grades like 316 stainless steel, which can handle the corrosive pressures. Even if your steel pieces won’t be immersed in a harsh environment, splashes and leaks can factor into the speed of corrosion.
Does stainless steel rust? Sure, but you can guarantee your stainless steel products avoid corrosion. Avoiding rust starts at the design phase of production. To reduce surface rust, you can design plants and production lines to ensure stainless steel is used in areas with minimal water penetration and free air circulation. When forging and fabricating metal pieces, ensure the steel alloy avoids cross-contamination with other metals that may reduce corrosion resistance. Preventing contact with iron and carbon steel is an essential precaution to take. Many operators outsource their steel forging needs to dodge these risks, as professional steelworkers are trained to take as many precautions as possible.
Once you’ve designed and fabricated your stainless steel pieces, the next step to minimising the impacts of rust is to ensure you’re maintaining the metal properly. If any rust has appeared, remove it as quickly as possible. After mechanical or chemical cleaning, remember to clear the grime using warm water and soap, then apply a rust-resistant coating if possible.
If you follow these steps, your stainless steel will rust exceptionally slowly. You can extend this slowness by using high-quality austenitic stainless steel with high chromium content. Stainless steel is renowned for its resistance to rust, making it a fantastic choice for your projects.
How we can help
At Greg Sewell Forgings, we appreciate the importance of creating high-quality metal components that are built to last. We can assist your projects from start to finish. We can design steel components for a range of industries, creating elegant designs that will keep your stainless steel in pristine condition for as long as possible.
Does stainless steel rust? Not if we can stop it. Our team of experts holds itself to the highest possible standards of efficient and careful service. We offer a range of fabrication services, ranging from stainless steel threading to custom CNC machining. As one of Australia’s oldest forging companies, we have a depth of experience that guarantees we can help you design, create and maintain steel components. If you have a project that requires metalworking expertise, get in contact today!