440A vs 440C Martensitic Stainless Steels: Balanced Corrosion vs Max Wear Resistance

 

What are their core compositions and performance differences?

440A contains 0.60–0.75% C, 16–18% Cr, ≤0.75% Mo-heat-treatable to 56HRC (balanced wear/corrosion).440C features 0.95–1.20% C, 16–18% Cr, ≤0.75% Mo-heat-treatable to 60HRC (max wear resistance, lower corrosion resistance).Both are magnetic and require quenching/tempering to harden.

How do their properties suit distinct applications?

440A is used for low-wear tools: kitchen knives, small bearings (dry indoor environments).440C dominates high-wear parts: surgical scalpels, precision bearing races (demands edge retention).

How do their corrosion resistances compare?

440A tolerates dry indoor/mild humidity (best in 440 series).440C rusts quickly in humid settings-requires coatings for outdoor use.

What are the heat treatment guidelines?

440A: Quench 1010–1060°C, temper 150–200°C (balance hardness/toughness).440C: Quench 1010–1070°C, triple temper 150–200°C (eliminate retained austenite).

What are the key guidelines?

Neither grade suits marine/chemical environments-upgrade to 17-4 PH.Prioritize 440A for balanced wear/corrosion; select 440C for max wear resistance (dry settings only).