Which element is the primary austenite-nucleating alloying addition for non-magnetic behavior in stainless steel when over 6%?

Which element is the primary austenite-nucleating alloying addition for non-magnetic behavior in stainless steel when over 6%?

• A. Chromium
• B. Nickel
• C. Iron
• D. Vanadium

Answer: (B)

Nickel is the strongest element that stabilizes the austenite phase in stainless steel. When its content is above about 6%, the face-centered cubic (FCC) austenite structure is retained at room temperature, and that phase is non-magnetic. That’s why austenitic stainless steels, which typically contain several percent nickel (around 8–12%), are non-magnetic and ductile. Chromium, while vital for corrosion resistance, tends to promote ferrite more than austenite, especially in lower-Ni grades, and vanadium mainly forms carbides for strength rather than stabilizing austenite. Iron is the base metal, and it doesn’t by itself drive the non-magnetic austenitic structure. So the primary austenite-stabilizing addition that yields non-magnetic behavior when over 6% is nickel.

Nickel is the strongest element that stabilizes the austenite phase in stainless steel. When its content is above about 6%, the face-centered cubic (FCC) austenite structure is retained at room temperature, and that phase is non-magnetic. That’s why austenitic stainless steels, which typically contain several percent nickel (around 8–12%), are non-magnetic and ductile. Chromium, while vital for corrosion resistance, tends to promote ferrite more than austenite, especially in lower-Ni grades, and vanadium mainly forms carbides for strength rather than stabilizing austenite. Iron is the base metal, and it doesn’t by itself drive the non-magnetic austenitic structure. So the primary austenite-stabilizing addition that yields non-magnetic behavior when over 6% is nickel.