Austenitic stainless steels offer:
- Improved weldability
- Resistance to a great variety of corrosives
- Good castability, machinability, weldability
- Improved strength at elevated temperatures
Typical uses and applications for austenitic stainless steels include:
- Paper pulp solutions and nitric acids
- Hot sulfuric acids
- Dilute hydrochloric acid and hot chloride solutions
- Nitric-hydrofluoric pickling solutions
Martensitic stainless steels are:
- Resistant to atmospheric corrosion
- Resistant to mild organic media in mild service
- Hardenable through heat treatment
In addition, these steels:
- Have good impact resistance
- Offer improved elevated temperature strength properties
- Have improved seawater corrosion resistance with additions of molybdenum
Martensitic stainless steels are commonly used for:
- Pumps, compressors
- Valves
- Hydraulic turbines
- Propellers
- Machinery components
Duplex stainless steels:
- Are about twice as strong as regular austenitic or ferritic stainless steels
- Have a range of corrosion resistance
- Show good stress corrosion cracking resistance
- Have lower nickel and molybdenum contents than their austenitic counterparts of similar corrosion resistance, resulting in lower cost
Duplex stainless steels are commonly used in applications that have exposure to chlorides and require crevice corrosion resistance.
Heat resistant stainless steels provide:
- Scaling resistance at high temperatures
- High sulfur applications where high strength is not required
- Corrosion resistance at high temperatures (moderate strength)
- Resistance to thermal fatigue and shock induced by severe temperature cycling
Common applications for heat-resistant stainless steels include:
- Ore roasting furnace parts, rabble arms and blades, steel mill furnaces
- Salt pots
- Grate bars
- Tube supports and beams in oil refinery heaters
- Scaling resistance at high temperatures
- Radiant tubes
- Oxidizing and carburizing atmospheres
Precipitation hardened stainless steels offer:
- Excellent resistance to stress corrosion and cracking in substances containing chloride (e.g. seawater)
- High resistance to sulfuric acid and nitric acids
Precipitation/age-hardened stainless steels are commonly used where high strength and improved corrosion resistance are required. For example:
- Highly stressed machined castings in the aircraft and food processing industries
- Pumps
- Valves
- Stressed components in the marine, chemical, textile and paper industries
Nickel-base alloys are most often alloyed with a particular element to impact certain properties. They are known for:
- High strength
- Toughness
- Resistance to mineral acids
- Resistance to organic acids and salts
Nickel-base alloys are commonly used for:
- Fluid handling systems, such as pump and valve components
- High velocity fluid or crevice applications
- Caustic soda processing components
- Applications which encounter hot corrosives or corrosive vapors
Wear-resistant cast iron offers:
- Resistance to oxidation
- Resistance to the impacts of high-sulfur flue gas
Wear-resistant cast iron is best used in low stress applications that do not require impact strength.
