Stainless steel is an iron-chromium alloy known for its corrosion resistance. The most common questions are what it is made of, whether it contains nickel, whether it is magnetic, whether it rusts, what types exist, and how duplex differs from super duplex. This guide answers each briefly and links to the full article; Langley Alloys specialises in duplex, super duplex and nickel grades.
What is stainless steel made of?
Stainless steel is an iron-based alloy with at least 10.5% chromium, which forms a self-repairing passive layer that resists corrosion. Nickel, molybdenum, nitrogen and carbon are added in varying amounts to tune each grade's strength, structure and corrosion resistance. Read more in our guide to what stainless steel is made of.
Does stainless steel contain nickel?
Some grades do and some barely any. Austenitic stainless steels typically contain 8-14% nickel to stabilise their structure, duplex grades use less, and ferritic and martensitic grades contain little or none. Nickel adds toughness and high-temperature performance but raises cost. See whether stainless steel contains nickel for the full picture.
Is stainless steel magnetic?
It depends on the family. Austenitic grades such as 304 and 316L are generally non-magnetic, while ferritic, martensitic and duplex grades are magnetic because they contain ferrite. The microstructure, not the stainless label, decides. Our article on whether austenitic stainless steel is ferrous explains why.
Does stainless steel rust?
Stainless steel resists rust but is not rust-proof. Its chromium passive layer normally prevents corrosion, yet it can still rust in chlorides, tight crevices, strong acids, or when contaminated by ordinary carbon steel. Higher-alloy grades resist the worst conditions. Learn when stainless steel rusts and how to avoid it.
What are the types of stainless steel?
Stainless steels fall into five families set by microstructure: austenitic, ferritic, martensitic, duplex including super duplex, and precipitation-hardening. Each balances corrosion resistance, strength and formability differently, from everyday 304 and 316L to high-performance duplex grades. See the types of stainless steel for a comparison table.
What is the difference between duplex and super duplex?
Both have a two-phase austenitic-ferritic structure, but super duplex carries more chromium, around 25% versus 22%, raising its pitting resistance equivalent number from about 34 to above 40. Both are roughly twice as strong as austenitic stainless. Read duplex versus super duplex stainless steels for detail.
Langley Alloys stocks the higher-alloy grades behind many of these answers - explore our super duplex and duplex ranges.