420F or 416 for a turned stainless part?

Both are resulfurized free-machining grades. 416 is softer and the machining champion; 420F carries more carbon and can be hardened to ~50 HRC, so it wins where the part must also resist wear.

Grades · Stainless Steel · 420F

420F

Data verified

420F is the free-machining version of 420, resulfurized (0.15% S minimum) so that hardened stainless parts can be produced economically on automatic lathes. It keeps 420’s hardenability to around 50 HRC but gives up corrosion resistance and weldability for chip-breaking.

Hardness40–52 HRC typical

AISI420F (UNS S42020)

JISSUS420F

CategoryStainless Steel

Chemical composition

Element	Content (%)
C	≥0.15
Si	≤1.00
Mn	≤1.25
P	≤0.060
S	≥0.15
Cr	12.00–14.00
Mo	≤0.60

Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.

Properties

Delivery condition	Annealed (hardened for use)
Hardness (hardened)	40–52 HRC typical
Density	7.70 g/cm³
Magnetic	Yes

Heat treatment

Anneal 840–900 °C slow cool; harden 980–1035 °C oil/air; temper 150–370 °C, as for 420.

Equivalent grades

Standard	Designation
aisi	420F (UNS S42020)
jis	SUS420F

Compare side by side: 420F vs 420 · 420F vs 416

Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.

Applications & Processing

Applications: Valve and pump trim, fasteners and fittings in stainless, instrument parts, gears and shafts needing a hardenable stainless with high machining output.

Processing: Machines far faster than 420 in the annealed state; the high sulfur makes it unsuitable for welding and reduces corrosion resistance, especially in the hardened condition’s sulfide sites.

FAQ

420F or 416 for a turned stainless part?: Both are resulfurized free-machining grades. 416 is softer and the machining champion; 420F carries more carbon and can be hardened to ~50 HRC, so it wins where the part must also resist wear.

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Source: ASTM A276 published ranges (UNS S42020) · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.