What is stainless steel and why collect it for scrapping?

Introduction:

Stainless steel is a very strong and durable metal that is used in many different types of products. It is often seen in kitchen appliances, cookware, jewellery, and other items. stainless steel is made up of several different metals that are mixed together to create a strong metal. So let’s give you a stainless steel 101, and what makes it up.

What is stainless steel?

Stainless steel is made of iron, carbon, and at least 10.5 percent chromium. This is where the chromium comes in. It reacts with oxygen to make a layer that protects the steel from corrosion. That protects stainless steel from rusting, which is important for outdoor site furnishings, like bollards, that are installed in wet areas. The more chromium there is, the better the corrosion resistance.

Carbon makes up about 1.2% of stainless steel and provides its resistance to corrosion. Tin makes up about 3% of stainless steel and helps it to resist rust and also has a low reactivity. But there amounts vary. If you want stainless steel, you’ll have to have at least 10.5 percent chromium in it. The components and ratios will change depending on the grade you want and the use you want the steel for.

But what is carbon steel?

You probably know already but when iron and carbon are mixed together, they make steel, this is also called carbon steel.

It is one of the most common types of steel, and it is often used in construction projects because it is strong and can resist corrosion. Carbon steel has a small amount of carbon in it, whereas stainless steel is a type of steel that has a larger amount of carbon in it, as well as chromium. Carbon steel is a ferromagnetic material meaning that it has the ability to be attracted to magnets. The carbon content in the steel affects the magnetic properties with higher carbon concentrations resulting in a stronger magnetism.

There are four general types of carbon steel.

1. Low carbon steel or mild steel

Low carbon steel has 0.04–0.3 percent carbon content and is the most common type of carbon steel. Mild steel is also called low carbon steel because it has a low carbon content of 0.05–0.25%. Mild steel is very ductile and can be made into many different shapes. It can be used to make things like car body parts, plates, and wire. If you add manganese up to 1.5% to the low carbon content range, the mechanical properties are good enough for stampings, forged parts, seamless tubes and boiler plates.

2. Medium carbon steel

In general, medium-carbon steel has a carbon content range of 0.31% to 0.61%, and a manganese range of 0.6% to 1.65%. To make it even better, you can heat treat and quench this steel to change its microstructure and mechanical properties more. Shafts, axles, gears, rails, and railway wheels are some of the most common applications.

3. High carbon steel

Carbon in high carbon steel ranges from 0.6% to 1.0%. It also has 0.3–0.9% manganese. High carbon steels can be used to make springs and wires with a lot of strength. These items can’t be welded unless a detailed heat treatment plan is included in the welding process. It’s used for things like cutting tools and wires with a lot of strength.

4. Ultra-high carbon steels

These steels have a range of 1.25–2% carbon, and they are regarded as experimental alloys because they were made to see how they worked. Tempering can make steel that is very hard, which is good for things like knives, axles, and punches.

Carbon helps iron be more hard and strong. However, too much carbon can cause problems, like when carbide forms during welding. It is very important to calibrate and reduce the carbon content of molten stainless steel to the right level before you can cast it. There are two ways foundries can control the amount of carbon in their metal.

When you use Argon Oxygen Decarburization, you get rid of a lot of things that you don’t want (AOD). To make the steel less carbon-based, you can add an argon gas mixture into it. This reduces the carbon content while causing little damage to other parts.

VOC Decarburization is also used (VOD). Molten steel is moved to another chamber, where oxygen is pumped into it while heat is used, in this method of making steel, Once all the gases that have been released are gone, a vacuum comes in and takes them away from the chamber. Even more carbon is removed, so the carbon content is even less. This makes it even less carbon-based.

Carbon steel rusts, conversely, chromium helps to make the steel less reactive with other elements and also gives it a nice shine.

The vast majority the steel you will encounter in scrapping will be a form of carbon steel.

Advantages of Stainless Steel

Stainless steel has a wide range of surface finishes, from matte to bright and including distressed and etched. It can be engraved or coloured, making it both unique and aesthetically pleasing at affordable prices. It is usually used by architects and interior designers for building envelope, interior design, and street furniture.

Unlike other substances, stainless steel has exceptional mechanical properties at ambient temperatures – it’s steel, after all! In particular, it combines ductility, elasticity and hardness, allowing it to be employed in tough metal forming modes (deep stamping, flat bending, extrusion, etc.) while offering resistance to heavy wear (friction, abrasion, impact, elasticity, etc.).

Surprisingly, when used in structural applications, stainless steel has the best fire-resistance of any metal when exposed to temperatures over 800 degrees. Stainless steel is rated A2s1d0 for fire-resistance without toxic fume emission.

This one goes without saying. Stainless steel is protected with a passive layer of chromium oxide that forms naturally on the surface through the interaction of chromium and oxygen from air or liquid. If the surface is damaged, it regenerates itself, rendering stainless steels resistant to corrosion.

Stainless steel is safe and easy to clean like plain dishes, dish soaps, and laundry detergents. Stainless steel perfectly serves the functions of cookware and tableware that require regular and effective cleaning.

Its recyclable. Well, that’s why you are here isn’t it.

Stainless steel properties

Different chromium levels of stainless steel will give it different properties, with a lower chromium content generally producing a cheaper but less durable steel. There are various types of stainless steel, which include:

• Austenitic, Type of stainless steel that is used the most: this type of stainless steel has a low yield strength but is strong at resisting corrosion and heat. It is used in things like housewares as well as in industrial piping and vessels, construction, and architectural facades.
• Ferritic, a type of steel that doesn’t have a lot of nickel in it, which makes it more resistant to corrosion, heat, and cracking than other types of steel. It’s used in things like washing machines, boilers, and indoor architecture.
• Stainless steel that has a lot of chromium, like Martensitic, is magnetic and less corrosion-resistant than other stainless steels because it has a lot of chromium. Martensitic is hard and strong, so it is used to make knives and blades for aeroplane engines.
• In the paper, pulp, shipbuilding, and petrochemical industries, duplex steel is used because it is both strong and flexible. It has twice the yield strength of austenitic stainless steel, which is used in paper and pulp.
• Precipitation, with the corrosion resistance of austenitic metals, but can be hardened to higher strengths, and so can be made to be extremely strong when other elements like aluminium, copper and niobium are added

Is Stainless Steel magnetic?

No -well sort off, which means your magnet really is your friend. Note that stainless steel does spark on a spark test. This can help differentiate it from Aluminium. In fact Martensitic and ferritic stainless steels are magnetic and this is important for scrappers to know and understand.

Whether or not it is magnetic comes down to how the steel is made. They can be magnetic because they have a “ferritic” structure (see above). Remember the chromium? To make it look like ferritic, chromium is added. This, along with the addition of carbon, makes the steel stronger and makes it a martensitic steel. Stainless steel knives are usually made of martensitic steel.

Martensitic steel is different from the most common types of stainless steel, which are called austenitic. In austenitic steel, there is a lot more chromium, and nickel is also there. It is the addition of nickel that makes steel not magnetic.

Conclusion

Stainless steel is more valuable than steel because it is resistant to corrosion and rust. Steel will corrode and rust over time, which will make the metal brittle and weak. This makes stainless steel more valuable for industrial and construction applications. It also means your local scrap yard will give you more money for it. Certainly, stainless steel is not as lucrative as copper but its still worth separating.

It is worth noting however that if your stainless steel is magnetic, it needs to go in the steel pile and not the stainless steel pile, or your scrap yard will penalise you. They have magnets too!!!