There are many grades but most types of steel fall into two broad categories,carbon steels and stainless steels.Both Carbon and Stainless Steel have the same basic composition of iron and carbon, stainless steel also have a variety of other alloy elements, as nickel,chromium,etc.In this blog post we analyze carbon steel vs stainless steel.
Stainless steel refers to a type of steel with corrosion resistance,an alloy steel containing high chromium (usually 12%~30%), Its main components are iron, chromium (Cr) and nickel (Ni). Carbon steel is an iron-carbon alloy whose main components are iron and carbon.
Stainless Steel
Stainless acid-resistant steel is referred to as stainless steel. It is composed of two parts: stainless steel and acid-resistant steel.Steel that can be resistant to weak corrosive media such as air, steam, and water are called stainless steel;while steel that can be resistant to chemical corrosive media (chemical corrosion such as acids, alkali, salts, etc.) are called acid-resistant steel.Stainless steel is a high-alloy steel with more than 60% iron as the base and added alloying elements such as chromium, nickel, and molybdenum.
Is Stainless Steel Rust?
When the chromium content in steel is more than 12%,the stainless steel will not easily corrode and rust in air and dilute nitric acid.The reason is that chromium can form a very tight chromium oxide film on the surface of steel, effectively protecting the steel from corrosion.Stainless steel is therefore given a protective layer of chromium to create a barrier between environmental oxygen and the metal's iron content.This allows it to resist corrosion or rust and makes it 'stainless.'
The chromium content in stainless steel generally more than 14%, but stainless steel is not absolutely free from rust. In coastal areas or some places with serious air pollution, when the chloride ion content in the air is high, some rust spots may appear on the surface of stainless steel exposed to the atmosphere.However, these rust spots are limited to the surface,will not corrode the internal matrix of the stainless steel.
Stainless Steel Categories
Generally,steel with a Cr content greater than 12% has the characteristics of stainless steel.Different chromium levels of stainless steel will give it different properties, with a lower chromium content generally producing a cheaper but less durable steel.
Stainless steel can be divided into several categories according to its trace elements and microstructure after heat treatment.
- Austenitic Stainless Steel, the most widely used type of stainless steel, with low yield strength but strong corrosion and heat resistance, this is the largest family of stainless steel and makes up about two thirds of all stainless steel production
- Ferritic Stainless Steel, a form of steel generally with no nickel, often possessing better corrosion, heat, and cracking resistance than more common types
- Martensitic Stainless Steel, which tends to be magnetic and less corrosion-resistant than other stainless steels due to its low chromium content – these matels are very hard and strong
- Duplex Stainless Steel, a composite of austenitic and ferritic steels, making it both strong and flexible, with twice the yield strength of austenitic stainless steel
- Precipitation Stainless Steel, 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
Stainless Features
- Excellent corrosion resistance: Due to the content of chromium and nickel, stainless steel has excellent corrosion resistance in humid environments and acid and alkali conditions.
- High temperature resistance: Stainless steel can maintain good mechanical properties at high temperatures and is suitable for high temperature environments.
- Easily cleaned: The surface of stainless steel is smooth, not easy to accumulate dirt, and easy to clean, complying with hygienic standards.
- Beautiful: Stainless steel has a unique metallic luster and modern feel, and is often used in architectural decoration and household items
Stainless Steel Advantages
- Corrosion resistant properties
- High and low temperature resistant
- Exists in a large variety of types
- Strong and highly durable
- Low maintenance and easily cleaned
- Long lasting, with a relatively low cost over the course of its lifecycle
- Can be given a surface finish if attractive cosmetic appearance is desired, and does not tarnish easily
- Environmentally friendly and recyclable
Carbon Steel
Carbon steel is a carbon-iron alloy whose main components are iron and carbon,generally does not contain a large amount of alloying elements. It is sometimes also called plain carbon steel or carbon steel.Carbon steel is widely used in construction, machinery manufacturing, automobile industry and other fields.
Types of Carbon Steel
The defining element of any carbon steel alloy is its carbon content.Depending on the carbon content, carbon steel can be divided into the following categories:
- Low carbon steel:carbon content less than 0.25%
- Medium carbon steel:carbon content between 0.25%-0.60%
- High carbon steel:carbon content above 0.60%
Generally, the higher the carbon content in carbon steel, the greater the hardness and strength, but the less ductile
Carbon Steel Features:
- High strength: Carbon steel has high strength and hardness, especially high carbon steel.
- Good processability: Carbon steel has good forgeability and weldability, and is suitable for a variety of processing methods.
- Lower cost: Compared with stainless steel, carbon steel has lower production costs and is relatively cheaper.
Carbon Steel Advantages:
- Increased strength
- Less expensive than stainless steels
- Wear-resistant
- Durable and shock resistant
- Safe to handle and work with compared to other metals
- Environmentally-friendly and easy to recycle
Carbon Steel Disadvantages
- Strong and sometimes difficult to work with
- Brittle, not easily bent or moulded
- More susceptible to rust and corrosion
- Less attractive appearance, cannot achieve the finish of stainless steel
Difference between Stainless Steel and Carbon Steel
1. Different colors: Stainless steel contains more chromium and nickel metals, and its appearance is mostly bright silver. Carbon steel is mainly an alloy of carbon and iron, with relatively few other metal elements. The main color of its appearance is the color of iron, which will be much darker.
2. Different textures: Stainless steel contains many other metal elements and has a smooth surface. Carbon steel contains a lot of iron and carbon, which is iron-like in nature,the surface is not as smooth as stainless steel.
3. Different magnetism: The surface of carbon steel is magnetic and can be absorbed by magnets. Generally,Stainless steel is not magnetic under normal circumstances and will not be attracted by magnets.
4. Different carbon elements: Carbon steel mainly refers to steel whose mechanical properties depend on the carbon content of the steel, and generally does not add a large amount of alloying metal elements. The carbon content is less than 2%. In order to maintain corrosion resistance, stainless steel has a lower carbon content with the maximum not more than 1.2%.
5. Different alloy content: Carbon steel contains very few alloying elements, only a small amount of silicon, manganese, sulfur and phosphorus. Stainless steel contains other alloy elements, with the main chromium and nickel elements exceeding 12%.
6. Different corrosion resistance: carbon steel contains less alloy elements and has weak corrosion resistance, while stainless steel contains more chromium and nickel metal and has strong corrosion resistance.
Compared with Carbon Steel,the advantage Stainless Steel
- Corrosion Resistance: Stainless steel is more resistant to corrosion than carbon steel in most environments, especially humid, acidic or alkaline conditions,which makes it ideal in applications that require corrosion protection, such as marine facilities, chemical equipment, and food processing equipment.
- Long Service Life:Due to its corrosion resistance, stainless steel generally has a longer service life than carbon steel, reducing replacement and maintenance costs.
- Beautifual Appearance:Stainless steel has a bright appearance and is suitable for occasions that require high decoration and visual effects, such as interior and exterior decoration of buildings, kitchen equipment, etc.
- Heat resistance:Stainless steel can maintain its strength and oxidation resistance in high temperature environments, making it suitable for equipment and components operating at high temperatures.
- Hygiene:Stainless steel has a smooth surface, is not prone to the accumulation of bacteria, and is easy to clean. It is widely used in the fields of food processing and medical equipment.
Stainless steel has become a more ideal choice than carbon steel in many fields due to its advantages such as corrosion resistance, temperature resistance, mechanical properties, long service life, aesthetics and hygienic properties.
Carbon steel plays an important role in many engineering and manufacturing fields due to its high strength and low cost, while stainless steel is indispensable in special-demand applications due to its excellent corrosion resistance, high temperature resistance and aesthetics.
