Machining-Friendly SS · Free-Machining Stainless
Stainless Steel 420F
Stainless Steel 420F is a machining-friendly stainless steel — free-machining martensitic stainless. Typical values: 345 MPa yield, 7.74 g/cm³, rated to 760 °C. Available for CNC machining at FabDigit.
Properties
Typical room-temperature values in the Annealed condition. Metric first, imperial in gray. The bars show where 420F sits against the other 87 stainless steel grades in the catalog.
Datasheet
| Yield strength | 345 MPa50 ksi |
|---|---|
| Tensile strength | 760 MPa110 ksi |
| Hardness | 95 HRB≈ 213 HB |
| Density | 7.74 g/cm³0.28 lb/in³ |
| Specific strength (yield ÷ density) | 45 |
| Min service temp | -100 °C-148 °F |
| Max service temp | 760 °C1,400 °F |
| Electrical conductivity | 2.5 % IACS1.5 MS/m |
| Machinability | Excellent92 / 100 |
| Weldability | Poor20 / 100 |
| Formability | Fair40 / 100 |
| ISO 513 machining group | M |
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Against other stainless steel grades
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 420F is highlighted; hover a dot for its name, or open the interactive family chart.
Manufacturability
The process limits FabDigit's quote engine applies to 420F. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Excellent92 / 100 |
|---|---|
| ISO material group | M.4 |
| Cutting speed (rough / finish) | 140 / 170 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 4× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Conditions and tempers
How 420F is supplied and what each state is for. The default is what FabDigit quotes unless your drawing says otherwise.
| Condition | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
AnnealedDefault Temper | Softest supply state — for forming, or when you heat-treat after machining | — | — | — | — |
Hardened & Tempered Heat Treat State | Delivered at final hardness — no heat treat after machining | — | — | — | — |
Heat treatment and post-processing
Operations FabDigit's suppliers routinely run on 420F, ranked by how often they make sense for this grade.
Heat treatment
| Solution Anneal | Dissolve carbides; reset austenite (stainless) |
|---|---|
| Stress Relief | Reduce residual stress without changing structure |
| Quench & Temper | Achieve target hardness with controlled toughness28–55 HRC |
Post-processing
| Manual Deburr | Deburrstandard |
|---|---|
| Passivate (Citric) | Passivation |
| Edge Break (0.5mm) | Deburr |
| Passivate (Nitric / AMS 2700) | Passivation |
| Electropolish | Polish |
| Glass Bead Blast | Blast |
| Laser Mark | Marking |
| CMM Inspection | Inspection |
| FAI Report | Inspection |
| Individual Bag | Packaging |
Surface finishes for 420F
Coatings and treatments compatible with stainless steel on the processes 420F runs on. Pick them in the quote configurator or call them out on the drawing.
Passivation
- Electropolishing
- Passivation (Stainless Steel)
- Pickling
Plating
- Chrome Plating
- Electroless Nickel (EN)
- Gold Plating
- Hard Chrome Plating
- Nickel Plating
- Silver Plating
PVD Coating
- AlCrN
- AlTiN
- CrN
- DLC
- MoS2
- TiAlN
- TiB2
- TiCN
- TiN
- WC/C
- ZrN
Organic Coating
- Cerakote
- Epoxy Coating
- Painting
- Powder Coating
- PTFE Coating
CVD Coating
- CVD Al2O3
- CVD TiCN
- CVD TiN
- Multilayer CVD
Marking / Decoration
- Chemical Etching
- Dot Peen Marking
- Electro-chemical Etching
- Ink Stamping
- Laser Marking
- Mechanical Engraving
- Steel Stamping
- Vibro Engraving / Scribing
Black / Phosphate
- Black Oxide
Thermal Spray
- HVOF Coating
- Plasma Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 420F in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S42020
- JIS
- SUS420F
Stock forms
Raw-material forms FabDigit sources 420F in.
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.