Carbon steel
It mainly refers to the steel whose mechanical properties depend on the carbon content in the steel, and generally does not add a large amount of alloying elements, sometimes called plain carbon steel or carbon steel.
Carbon steel, also called carbon steel, refers to an iron-carbon alloy with a carbon content WC less than 2%.
In addition to carbon, carbon steel generally contains a small amount of silicon, manganese, sulfur, and phosphorus.
According to the application, carbon steel can be divided into three types: carbon structural steel, carbon tool steel and free-cutting structural steel, and carbon structural steel can be divided into two types: building structural steel and machine-made structural steel;
According to the smelting method, it can be divided into open hearth steel, converter steel and electric furnace steel;
According to the deoxidation method, it can be divided into boiling steel (F), killed steel (Z), semi-killed steel (b) and special killed steel (TZ);
According to the carbon content, carbon steel can be divided into low carbon steel (WC ≤ 0.25%), medium carbon steel (WC0.25%-0.6%) and high carbon steel (WC>0.6%);
According to the content of phosphorus and sulfur, carbon steel can be divided into ordinary carbon steel (higher phosphorus and sulfur), high-quality carbon steel (lower phosphorus and sulfur), high-grade high-quality steel (lower phosphorus and sulfur) and Extra high quality steel.
Generally, the higher the carbon content in carbon steel, the greater the hardness and the higher the strength, but the lower the plasticity.
Stainless steel
Stainless acid-resistant steel is called stainless steel for short. It is composed of stainless steel and acid-resistant steel. In short, the steel that can resist atmospheric corrosion is called stainless steel, and the steel that can resist chemical medium corrosion is called acid-resistant steel. Stainless steel is a high-alloy steel with more than 60% iron as the matrix and alloying elements such as chromium, nickel, and molybdenum.
When the chromium content in the steel exceeds 12%, the steel is not easy to corrode and rust in the air and dilute nitric acid. The reason is that chromium can form a very tight chromium oxide film on the surface of the steel, which effectively protects the steel from corrosion. The chromium content in stainless steel is generally more than 14%, but stainless steel is not absolutely rust-free. In coastal areas or some places with severe air pollution, when the content of chloride ions in the air is high, there may be some rust spots on the surface of stainless steel exposed to the atmosphere, but these rust spots are limited to the surface and will not erode the inner matrix of stainless steel. the
Generally speaking, steel with a content of Wcr greater than 12% has the characteristics of stainless steel. Stainless steel can be divided into five categories according to the microstructure after heat treatment: ferritic stainless steel, martensitic stainless steel, and austenitic stainless steel. , Austenitic-ferritic stainless steel and precipitated carbide stainless steel.
Stainless steel is usually divided according to the matrix structure:
1. Ferritic stainless steel. Chromium 12% to 30%. Its corrosion resistance, toughness and weldability increase with the increase of chromium content, and its resistance to chloride stress corrosion is better than other types of stainless steel.
2. Austenitic stainless steel. It contains more than 18% chromium, and also contains about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements. Good overall performance, resistant to corrosion by various media.
3. Austenitic-ferritic duplex stainless steel. It has the advantages of both austenitic and ferritic stainless steels, and has superplasticity.
4. Martensitic stainless steel. High strength, but poor plasticity and weldability.
The difference between carbon steel and stainless steel:
1. Different colors: stainless steel contains more chromium and nickel metals, and its appearance is mostly silver and bright. Carbon steel is mainly carbon and iron alloys, and other metal elements are relatively small. The main color of the appearance is the color of iron, and the color will be much darker.
2. Different textures: stainless steel contains many other metal elements and has a smooth surface, while carbon steel contains more iron and carbon nia, which has the essence of iron, and 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. Stainless steel is not magnetic under normal conditions and will not be attracted by magnets.
4. Different carbon elements: carbon steel mainly refers to the steel whose mechanical properties depend on the carbon content of the steel, and generally does not add a large amount of alloy metal elements, in which the carbon content WC is less than 2%. In order to maintain the corrosion resistance of stainless steel, the carbon content Both are low, and the maximum does not exceed 1.2%.
5. Different alloy content: carbon steel contains very few alloy elements, only a small amount of silicon, manganese, sulfur and phosphorus. Stainless steel contains a lot of gold elements, mainly 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-nickel metal and has strong corrosion resistance.
