Guide to Selecting Stainless Steel and Carbon Steel in Metal Fabrication

When starting on your next metal fabrication project, you should take careful consideration of the type of steel you intend to use. At Cncteck, we manufacture our metal fabrications using different varieties of steel. Out of the different kinds of steel, we commonly use stainless steel and carbon steel. Before you even contemplate on the grade of steel to use, we often first advise our clients on the type of steel to use. To help you reach a decision, here is further insight into the differences in features between carbon steel and stainless steel.

What’re the basics of Carbon Steel and Stainless Steel Material

Steel mainly comprises of iron with about 2% of carbon. If the carbon levels go above 2%, then it is referred to as cast iron. Though cast iron does have its useful applications, we do not normally use it in metal fabrication. When the carbon content is less than 1%, then the resultant metal is carbon steel. This type of steel usually has trace amounts of manganese, phosphorus, sulfur, silicon, and phosphorus. Lower carbon content makes the steel more machinable, ductile and much easier to weld.

Stainless Steel is mainly carbon steel with a large composition of chromium. The chromium levels are usually about 10.5%. Chromium has a considerably strong affinity for oxygen, which gives makes stainless steel ideally corrosion resistance. The plain carbon steel iron binds to oxygen, causing it to rust. On the other hand, in stainless steel, a chromium oxide compound binds to its surface, which prevents rust from forming. Additionally, when you scratch its surface, the newly exposed chromium establishes more rust-preventing oxygen bonds.

How to Choose Between Stainless Steel and Carbon Steel in Metal Fabrication

Depending on what you are trying to achieve, here are a few key factors you should look at.

• Finish or appearance
• Ductility
• Strength
• Weldability
• Cost

Finish/ Corrosion Resistance/ Appearance

Carbon steel in the metal fabrication process often needs a coating to prevent it from rusting. Powder coating and painting are commonly preferred options. Before painting or powder coating it, we first have to prepare the surface. Also, we occasionally perform a periodic touch up for paint jobs. Stainless steel does not require such coating unless you intend to use it in a strong chlorine environment. This is, for instance, in the sea air or swimming pool where chlorine-induced corrosion is likely to occur. We recommend the use of 316-grade stainless steel, which is chlorine resistant. Interestingly, we can perform a variety of finishes on stainless steel. We commonly brush stainless steel household appliances while we recommend polishing for other appliances to give them a mirror-like finish.

• Ductility

Ductility essentially refers to how readily a metal will stretch or bend without experiencing cracking. Bending operations, such as on press brakes, usually require metals with a lot of ductilities. We normally radius less ductile metal though they are likely to experience cracking if bent through sharp angles.

Carbon steel has excellent ductility. The ductility of stainless steel is heavily reliant on its composition. Austenitic stainless steel is known to have notable amounts of nickel in addition to chromium, which has good ductility. Stainless steel that has higher amounts of carbon lacks the ductility needed to use in fabrication easily.

• Strength

Experts at Cncteck know that the strength of most metals is inversely proportional to ductility. Stainless steel is usually stronger than any grade of carbon steel, which makes it harder to form.

• Weldability

As the levels of carbon rise in carbon steel, it becomes more difficult to weld. We normally perform preheating on it to enable a good weld when the carbon content is above 1%. Stainless steel is usually harder to weld because of its lower thermal conductivity than carbon steel. Austenitic stainless steel happens to weld easily since it has excellent conductivity. It normally does not experience hardening upon heating it. This, therefore, means that while welding, the affected zone does not harden. Welding may, however, increase its susceptibility to corrosion.

• Cost

Cost is an important consideration for any project. Though different grades vary in cost, stainless steel is usually more expensive than carbon steel. However, there are a few mitigating factors you should consider. Since stainless steel is stronger, you may able to use less of it. Also, since it is relatively more corrosion resistant, you do not incur painting expenses. As a result, considering the duration you may be using the fabrication, the cost differential significantly narrows.

What we can offer Stainless Steel and Carbon Steel in Metal Fabrication?

While stainless steel and carbon steel are different, one is not necessarily superior to the other as context matters. Each type of steel has its advantages and disadvantages which should help you match the steel to the job requirement. Furthermore, we also can offer you these secondary finishing services such as black oxide, powder coating, plating chrome, drawbench, nickel finishing, and more processes. At Cncteck, we are ready to simplify this decision making so contact us now with any inquiry on your next metal fabrication project.

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