Molybdenum (and Tungsten) Titanium (and Niobium & Zirconium)

Molybdenum (and Tungsten)

• Corrosion Resistance: Increases resistance to local (pitting, crevice) and general corrosion.
• High Temperature Strength: Added to martensitic steels.
• Ferrite Stabilizers: Used in austenitic alloys but balanced with austenite stabilizers.

Titanium (and Niobium & Zirconium)

• Intergranular Corrosion Resistance: Stabilizes stainless steel when low carbon control isn’t possible.
• Affinity for Carbon: Forms carbides, preventing chromium carbide formation and chromium depletion.
• Ferrite Stabilizers: Helps maintain structural stability

Chromium

• Importance: Chromium is crucial for stainless steel production.
• Minimum Requirement: At least 10.5% chromium is needed to form a protective chromium oxide layer on the steel surface.
• Protective Layer: The strength of this passive layer increases with higher chromium content.
• Structural Effect: Chromium induces the formation of ferrite within the alloy, acting as a ferrite stabilizer.

Nickel

• Corrosion Resistance: Nickel enhances general corrosion resistance.
• Formation of Austenite: Nickel promotes the formation of austenite, making it an austenite stabilizer.
• Nickel Content in Stainless Steel: Stainless steels with 8-9% nickel are fully austenitic, offering superior welding and working properties compared to ferritic stainless steels.
• Higher Nickel Content: Increasing nickel content beyond 8-9% improves both corrosion resistance (especially in acidic environments) and workability.