High Strength SS · Martensitic
Stainless Steel 440B
Stainless Steel 440B is a high strength stainless steel — cutlery-grade hardenable stainless. Typical values: 425 MPa yield, 7.81 g/cm³, rated to 650 °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 440B sits against the other 87 stainless steel grades in the catalog.
Datasheet
| Yield strength | 425 MPa62 ksi |
|---|---|
| Tensile strength | 1,080 MPa157 ksi |
| Hardness | 97 HRB≈ 224 HB |
| Density | 7.81 g/cm³0.282 lb/in³ |
| Specific strength (yield ÷ density) | 54 |
| Min service temp | -50 °C-58 °F |
| Max service temp | 650 °C1,202 °F |
| Electrical conductivity | 2.8 % IACS1.6 MS/m |
| Machinability | Fair40 / 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. 440B is highlighted; hover a dot for its name, or open the interactive family chart.
Manufacturability
The process limits FabDigit's quote engine applies to 440B. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Fair40 / 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 440B 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 440B, 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 440B
Coatings and treatments compatible with stainless steel on the processes 440B 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 440B in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S44003
- EN / DIN / Werkstoff-Nr.
- 1.4112
- JIS
- SUS440B
Stock forms
Raw-material forms FabDigit sources 440B 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.