Stainless steel is a versatile material prized for its strength and resistance to corrosion and oxidation. It is an alloy primarily made of iron, with a significant amount of chromium (at least 10.5%) which provides its stainless properties, along with varying amounts of other elements such as nickel, molybdenum, titanium, and copper. The different types of stainless steel are classified into families based on their microstructure, which affects their properties and uses. Here’s a breakdown of the main types:
1. Austenitic Stainless Steel
- Structure: Contains high levels of chromium and nickel, and often includes molybdenum to increase corrosion resistance. It is non-magnetic and cannot be hardened by heat treatment.
- Common Grades: 304 and 316, with 316 having more molybdenum for even greater corrosion resistance.
- Uses: Widely used in kitchen utensils, medical surgical instruments, food processing equipment, and in marine environments. This is the stainless steel that is used by the various manufacturers that supply our stainless steel cabinet offerings.
2. Ferritic Stainless Steel
- Structure: Contains higher chromium levels but much lower nickel content than austenitic. It is magnetic and has a microstructure similar to carbon steel.
- Common Grades: 430 and 446; 430 is used for good resistance to atmospheric corrosion and 446 for high oxidation resistance at elevated temperatures.
- Uses: Often used in automotive applications, appliances, and industrial equipment.
3. Martensitic Stainless Steel
- Structure: Contains moderate levels of chromium and low levels of nickel. Can be hardened and tempered by heat treatments.
- Common Grades: 410 and 420; 410 is suitable for less severe corrosion environments, while 420 is known for its higher carbon content for better edge retention.
- Uses: Commonly used in cutlery, surgical instruments, fasteners, and turbines.
4. Duplex Stainless Steel
- Structure: Combines the qualities of austenitic and ferritic, leading to high strength and excellent resistance to corrosion.
- Common Grades: 2205, which contains about 22% chromium, 5% nickel, and 3% molybdenum.
- Uses: Particularly useful in environments that are highly corrosive, such as chemical processing plants, oil and gas industry, and sea water equipment.
5. Precipitation Hardening Stainless Steel
- Structure: Can be both austenitic or martensitic in the base state but are hardened by a process of aging that precipitates out hardening phases in the metal.
- Common Grades: 17-4PH and 15-5PH, which include elements like copper, niobium, and aluminum.
- Uses: Used in aerospace, chemical processing, and high-stress applications needing high strength and moderate corrosion resistance.
Each type of stainless steel is selected based on the specific environmental conditions and performance requirements it needs to meet. The choice of grade impacts the material’s ability to resist corrosion, withstand temperature extremes, and maintain structural integrity under stress.
