Stainless steel is a material that has revolutionized our domestic and industrial applications. It offers remarkable durability, strength, and corrosion resistance which is why it is found in everything from cutlery knives to skyscrapers. But what exactly is stainless steel?
Let’s discuss all details of this alloy, including its types, classes, and feasibility.
An Overview.
Stainless steel is a category of steel. The alloy contains at least 10.5% chromium in its composition, and you can also add other elements like nickel, molybdenum, and titanium to enhance its properties. This gives it high resistance to corrosion, rust, and staining.
They introduce properties like strength, durability, and resistance to heat and wear in the material.
Stainless steel comes in different types, series, and grades. We’ll discuss them below.
Types of Stainless Steel.
This material can be divided into different categories on the basis of its composition:
1. Austenitic.
This is the most commonly used type of stainless steel, and it contains chromium, nickel, and molybdenum. You’ll find it non-magnetic and highly resistant to corrosion, rust, and staining. As a result, you can use austenitic stainless steel in sensitive applications, like implants.
These steels have good weldability and foamability and are used in various applications, such as kitchenware, medical equipment, and architectural structures.
2. Ferritic.
This category has alloys with high concentrations of chromium and relatively lower concentrations of nickel. It’s stable against chemical forces and heat, so it’s used in applications requiring high-temperature resistance, such as heat exchangers, automotive exhausts, and appliances.
Ferritic stainless steels are magnetic, justifying their use in applications where magnetic properties are favorable, such as transformers and electric motors.
3. Martensitic.
These steels are characterized by their high carbon levels and lower nickel levels, granting them superior strength. However, this makes them slightly less tolerant to corrosion than other types of stainless steel, especially in acidic environments.
Martensitic stainless steels are also less heat-tolerant than steels. Due to their exceptional hardness and considerable chemical stability, you’ll primarily find them in cutting tools, kitchen knives, and other sharp objects.
4. Duplex.
Alloys in this category are known for their excellent hardness and corrosion resistance. They contain almost equal parts of austenitic and ferritic phases– a combination that makes them highly durable.
You’ll find duplex steels excellent for applications that require high strength, such as oil and gas pipelines, chemical processing equipment, and off-shore structures.
5. Precipitation-Hardening Stainless Steel.
This category contains alloys with high levels of chromium, nickel, and copper, making them strong, tough, and resistant to corrosive agents. Due to its high strength, PH steel is commonly used in aerospace and other demanding applications.
Stainless Steel Series
Stainless steels are also classified into different series; let’s discuss the standard ones.
- 200 stainless steel series: Instead of nickel, this series makes use of a high manganese concentration. This makes them relatively cheaper. You’ll find the 200 series in food processing and the automotive industry.
- 300 stainless steel series: This series contains high levels of nickel, making its grades highly corrosion-resistant. They are used in many applications, such as architectural structures and medical equipment.
- 400 stainless steel series: The 400 series materials have a high carbon content, but they are relatively less corrosive. They are mostly used in knives and other sharp objects.
- 500 stainless steel: Materials in this series have large amounts of chromium and molybdenum added to them. They are highly temperature resistant and are used in automotive exhausts and heat exchangers.
- 600 stainless series: These grades are both temperature and corrosion-resistant. They are found in gas turbines and processing equipment.
How to Manufacture Stainless Steel.
Here is an overview of the manufacturing process.
- Melting and refining: First, you melt and refine the raw materials. These include iron, nickel, chromium, and other alloying elements, which are melted in a furnace and refined to remove impurities.
- Casting: Once the materials are melted and refined, you cast them into ingots or billets.
- Hot rolling: You then heat your ingots or billets and pass them through a series of hot rolling mills. These flatten and shape them into the desired form, such as sheets, bars, or coils.
- Cold rolling: After hot rolling, you have to cold-roll the steel. You do this by passing the material through multiple of cold rolling subsequently. This shapes it shape further.
- Annealing and pickling: You treat the cold-rolled steel by heating it to a high temperature and cooling it slowly. This improves the material’s ductility and strength.
You then pickle your alloy and treat it with acid to remove any impurities and improve its surface finish.
- Finishing: This involves various processes to give the material its final shape and surface finish.
This may include cutting, polishing, or other techniques, depending on the application and intended use of the stainless steel.
Factors Affecting the Quality of Stainless Steel
The quality of stainless steel is affected by various factors, including material sourcing, the manufacturing process, the finishing process, and surface treatment.
- Material sourcing: The quality of stainless steel heavily depends on the quality of its raw materials – the purity of the metal.
- Manufacturing process: As we saw, the manufacturing process of steel has multiple steps, including melting and refining, casting, hot rolling, cold rolling, annealing, pickling, and finishing. You must carefully control all these steps to ensure the resulting stainless steel has the desired quality.
- Finishing processes: Finishing is an essential step in producing high-quality stainless steel.
You must execute the finishing processes such as cutting, polishing, and buffing carefully to avoid damaging the surface of your stainless steel.
- Surface treatment: Treatments such as powder coating, electropolishing, and chemical cleaning can improve the surface finish of the material and make it more resistant to corrosion and other forms of wear and tear.
How Does Stainless Steel Compare with Other Materials?
Here’s how this alloy performs against a few common materials:
Stainless vs. Carbon Steel
When compared to carbon steel, stainless steel is a lot more corrosion-resistant. It’s used over carbon steel in harsh environments. Stainless steel is also more ductile than carbon steel, which makes it more resistant to stress in demanding operations.
Stainless Steel vs. Aluminum
Stainless steel is more durable than aluminum. It has more tensile strength than aluminum which is why it is used in applications that require high strength and durability.
Stainless Steel vs. Plastics
Stainless steel has a higher lifespan than most plastics. And it is generally stronger and more eco-friendly than plastics. It can also withstand high temperatures and is easier to clean than most plastics.
Benefits and Drawbacks of Stainless Steel.
The advantages of stainless steel often outweigh its disadvantages. Let’s look at them side-by-side.
| Advantages. | Disadvantages. |
| Stainless steel is highly corrosion-resistant. | It is generally most costly than other materials. |
| It is durable and resistant to wear and tear. | It is relatively heavier than other alternatives, which can be a disadvantage in applications where weight is a negative factor. |
| The material has a modern and sleek appearance, making it popular in consumer goods. | It is difficult to work with due to its high hardness. |
| Stainless steel is hygienic, non-porous, and easy to clean. | Despite its durability, stainless steel is highly susceptible to getting scratched over time. |
| You can indefinitely recycle and reuse it. |
Endnote
Stainless steel is a versatile material used in various industries due to its unique properties. Understanding the types, manufacturing processes, and properties is essential for anyone looking to invest in stainless steel for their project.
Although this material has many advantages, you must also be aware of its limitations, like its cost.
If you have any further questions or you are looking to buy or set an inquiry about stainless steel products, then feel free to contact us to set an inquiry today.
FAQs
- Can stainless steel corrode?
Yes, stainless steel can rust. Although the material is resistant to corrosion, prolonged exposure to moisture and oxygen can start damaging the surface of the substance. Exposure to abrasive chemicals such as acids and chloride ions can also cause the stainless steel to rust.
