STAINLESS STEEL WITH THEIR GRADES

Stainless steels are iron-base alloys containing 10.5% or more Chromium. Other alloying elements may be added during melting, such as Nickel, Molybdenum, Columbium, or Titanium, which serve to change or enhance certain properties of characteristics.

Several methods are commonly used to identify stainless steels.

They are:

• Classification by metallurgical structure – Austenitic, Ferritic, Martensitic, Precipitation hardening, or Duplex which we have already discussed.
• Designation by the AISI numbering system – namely 200, 300, and 400 series numbers. This is what we going to discuss now which comes under stainless steel grades.
• Designation by the Unified Numbering System, which ASTM and SAE developed to apply to all commercial metals and alloys.
• Trade names – which are generally, used with proprietary or special analysis stainless steels.
• Abbreviated composition.

Here we will discuss on stainless steel grades which is the second identification method from the above five methods.

Different Stainless Steel Grades

Type 304 – These stainless steel grades serves a wide range of applications. It withstands ordinary rusting in architecture; it is resistant to food-processing environments (except possibly for high-temperature conditions involving high acid and chloride contents), it resists organic chemicals, dyestuffs, and a wide variety of inorganic chemicals. Type 304 L (low carbon) resists nitric acid well and sulfuric acids at moderate temperature and concentrations. It is used extensively for storage of liquid gases, equipment for use at cryogenic temperatures (304N), appliances and other consumer products, kitchen equipment, hospital equipment, transportation and waste-water treatment.

Type 316 – In this stainless steel grades, it contains slightly more nickel than Type 304, and 2-3% molybdenum giving it better resistance to corrosion than Type 304, especially in chloride environments that tend to cause pitting. Type 316 was developed for cause in sulphite pulp mills because it resists sulphuric acid compounds. Its use has been broadened, however, to handling many chemicals in the process industries.

Type 317 – In these stainless steel grades, these contains 304% molybdenum (high levels are also inthis series) and more chromium than Type 316 for even better resistance to pitting and crevice corrosion.

Type 430 – Type 430 stainless steel grades has lower alloy content than Type 304 and is used for highly polished trim applications in mild atmospheres. It is also used in nitric acid and food processing.

Type 410 – Type 410 stainless steel grades has the lowest alloy content of the three general purpose stainless steels and is selected for highly stressed parts needing the combination of strength and corrosion resistance, such as fasteners. Type 410 resists corrosion in mild atmospheres, steam and many mild chemical environments.

Type 2205 – These stainless steel grades may have advantages over Type 304 and 316 since it is resistant to chloride stress corrosion cracking and is about twice as strong.