How is steel made?
The main raw material of iron making is iron ore, the main component of iron ore is Fe2O3, there is no carbon; the second raw material of iron making is coke, part of which is left in the molten iron during the iron making process, resulting in carbon content in the molten iron. The production of iron and steel is from iron ore to pig iron, and pig iron is used as raw material for steelmaking. The process of steelmaking is mainly the process of carbon removal, which can not be completely removed. Steel needs a certain amount of carbon to achieve the best performance.

In order to improve the properties of steel, some alloy elements need to be added on the basis of smelting carbon steel.
Pig iron (cast iron) - 2.0-4.5% C
Steel (carbon steel) - 0.05-2.0% C
Wrought iron (pure iron) - C content less than 0.05%
Iron ore → pig iron → steel

Therefore, iron and steel are alloys composed of C (carbon), Si (silicon), Mn (manganese), P (phosphorus), s (sulfur) and a small number of other elements. In addition to Fe (iron), the content of C plays an important role in the mechanical properties of steel, so it is called iron-carbon alloy. It is the most important and important metal material in engineering technology.

According to carbon content, it can be divided into:
According to the different carbon content, carbon steel is divided into low carbon steel, medium carbon steel, and high carbon steel. With the increase of carbon content, the hardness and toughness of carbon steel increase and decrease.
1) Low carbon steel - carbon content ≤ 0.25%.
2) Medium carbon steel -- carbon content > 0.25% ≤ 0.60%.
3) High carbon steel -- carbon content > 0.60%

According to the total content of alloy elements:
In order to improve the properties of the steel, the alloy steel, such as chromium steel, manganese steel, chromium manganese steel, chromium-nickel steel, is made by adding some alloy elements on the basis of smelting carbon steel. Alloy steel, also known as special steel, has some special properties, such as high hardness, high wear resistance, high toughness, corrosion resistance, and so on. The alloy elements often added to steel are Si, W, Mn, Cr, Ni, Mo, V, Ti, etc.

According to the total content of alloy elements, it can be divided into:
1) Low alloy steel - total content of alloy elements ≤ 5%.
2) The total content of alloy elements in medium alloy steel is 5% - 10%.
3) The total content of alloy elements in high alloy steel is more than 10%.

Alloy steel is classified by use:
1) Alloy structural steel: used as engineering components (pipes, supports, etc.); various mechanical parts (shafts, gears, springs, impellers, etc.).
2) Alloy tool steel: used as a measuring tool, mold, tool, etc.
3) Special performance steel: such as stainless steel, heat-resistant steel, etc., with special physical or chemical properties.

CNC steel/stainless steel machining: https://www.cnclathing.com/cnc-machining-stainless-steel