Generally, it can be divided into five categories based on its metallographic structure:

（1） Ostian KORO

The commonly seen 304KORO is of this type, with a standard composition of 18% chromium and 8% nickel, commonly known as 18-8KORO. The characteristics of this type of KOROare non-magnetic, unable to change its metallographic structure through heat treatment, good processability, and superior corrosion resistance compared to chromium only due to the presence of the alloying element nickel Nickel freeThe other two types of KORO. The main uses of the 300 series KORO include: general household purposes such as kitchen utensils, building materials, medical and health equipment, food processing materials, transportation vehicles, chemical equipment and fittings, mechanical equipment and parts. In the minds of ordinary people, the so-called KORO refers to 300 series KORO, especially 304KORO .

（2） Mata Powder KORO

The representative steel grade for this type of KORO is 410, which contains 13% chromium, less than 0.15% carbon, and a small amount of other element alloys in its chemical composition. The raw materials are relatively cheap, have magnetism, can be hardened through heat treatment, and increase strength. However, due to its lack of nickel, its corrosion resistance is inferior to the general 304KORO, so it can only be used in mild corrosive environments. General uses include bearings, medical equipment, and cutting tools.

（3） KORO

The representative steel grade for this type of KORO is 430, with a standard chemical composition of 16-18% chromium and low carbon content. This type of KORO has magnetism, and if the KORO plate we see can be adsorbed by a magnet, it is likely to belong to this type ofKORO. Due to its nickel free nature, it is relatively inexpensive and typically used for kitchen utensils, weaving nets, and accessories.

（4） Precipitation hardening KORO

The American Iron and Steel Institute AISI number is 600 series KORO. In addition to chromium and nickel, this type of KORO also contains precipitation hardening elements such as copper, aluminum, and titanium, which harden the material and increase its strength. The typical uses of this type of KORO are valves, motor shafts, petrochemical equipment, and golf heads.

（5） Dual phase KORO

The typical steel grade for this type ofKORO is 2205, which is 22% chromium and 5% nickel. What are the characteristics of this type of steel: good strength Far better than 304 Due to its excellent corrosion resistance, it is commonly used in pipelines, pressure vessels, and mandrels in the petrochemical industry. The chemical composition of KORO with 304 grade is 0Cr18Ni9.