Steel S2
AISI/SAE S2 · UNS T41902
S2 is a water-hardening, silicon-manganese-molybdenum shock-resisting tool steel (AISI/ASTM A681 S-series) with medium carbon and low total alloy content, giving very high impact toughness at 50–60 HRC.
Values for the Annealed condition
S2 tempers and conditions
S2 is supplied in 5 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft-annealed bar/flat, as supplied for machining | Standard stock condition (183–217 HB) for machining, forming and drilling before hardening. | 460 | 760 | 20 | 200 HB | — |
cold-drawn/ground bar and drill rod | Size-accurate drill-rod/ground-bar stock for bit and punch blanks; slightly harder than hot-rolled annealed. | 620 | 850 | 14 | 22 HRC | 5.5 % IACS |
900–925 °C air cool (mill pre-treatment before annealing) | Intermediate mill/forge-recovery condition; not a service condition — normally annealed afterwards. | 700 | 1,050 | 12 | 31 HRC | 5.5 % IACS |
Hardened & Tempered | Toughest practical working condition for chisels, rivet sets and pneumatic-hammer tooling under heavy shock. | 1,500 | 1,750 | 9 | 52 HRC | — |
Quenched and tempered | General hardened-and-tempered service condition (typically 54–58 HRC) for shock tools and bits. | 1,700 | 2,000 | 6 | 57 HRC | — |
What is S2?
S2 is a water-hardening, silicon-manganese-molybdenum shock-resisting tool steel (AISI/ASTM A681 S-series) with medium carbon and low total alloy content, giving very high impact toughness at 50–60 HRC. It is the classic grade for screwdriver bits, hex keys, chisels, punches, rivet sets and pneumatic tool components where repeated shock would crack a higher-carbon die steel. Limits are shallow hardenability with a severe water/brine quench (distortion and quench-crack risk), poor wear resistance versus D2/M2, no corrosion resistance, and rapid softening above the tempering temperature (~250 °C). S2 has a density of 7.79 g/cm³ (0.281 lb/in³), lighter than 90% of steel grades. It melts at 1,425°C (2,597 °F). S2 has a yield strength of 460 MPa (66.7 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 55% of steel grades. Elongation at break is 20% and the elastic modulus is 207 GPa (30 Msi).
What is S2 used for?
- Screwdrivers
- Pneumatic tool bits
- Chisels
Limitations
- Difficult to weld — 15/100, worse than 91% of steel grades
- Poor heat conductor — 25.5 W/m·K (14.7 BTU/hr·ft·°F), worse than 88% of steel grades
- Low electrical conductivity — 5.5 % IACS, worse than 81% of steel grades
S2 properties
Typical room-temperature values for S2-Annealed; bars are the position among steel grades.
Physical3
S2 has a density of 7.79 g/cm³ (0.281 lb/in³), lighter than 90% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
S2 has a yield strength of 460 MPa (66.7 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 55% of steel grades. Elongation at break is 20% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
S2 is rated for continuous service to 400°C (752 °F). It conducts heat at 25.5 W/m·K (14.7 BTU/hr·ft·°F), worse than 88% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
S2 conducts electricity at 5.5 % IACS, worse than 81% of steel grades.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of S2 takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 45%.
Manufacturability8
S2's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (15/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. S2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S2
Is S2 easy to machine?
Machine in the annealed condition with sharp carbide or cobalt HSS at moderate speed; the ~1 % Si makes chips gummy, so use generous coolant and finish-grind after hardening.
Can S2 be welded?
Not a welding grade — repair only, with 200–320 °C preheat, matching or austenitic filler, and an immediate re-temper to avoid quench cracks.
Can S2 be formed, bent or molded?
Forge 1010–1150 °C, never below ~900 °C, slow cool then anneal 760–790 °C; harden 845–885 °C with a severe water/brine quench (thin sections may be oil-quenched) and temper 175–370 °C for 50–60 HRC.
Manufacturability
The process limits FabDigit applies to S2. Every S2 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair45 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
S2 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | 0.4 – 0.55 | 0.5 |
| Siraises hardenability and tempering resistance | 0.9 – 1.2 | 1.05 |
| Mn | 0.3 – 0.5 | 0.4 |
| Mo | 0.3 – 0.6 | 0.45 |
| Voptional grain refiner | ≤ 0.5 | 0.2 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on S2?
Grind, then protect with black oxide, manganese phosphate or oil; thin electroplating requires post-plate bake (~190 °C) to avoid hydrogen embrittlement.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel S2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T41902
How much does S2 cost?
S2 is a high-cost steel ($$$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
S2 — frequently asked
What is S2 used for?
S2 is typically used for screwdrivers, pneumatic tool bits and chisels. In short: tough; water-hardening tool.
What is the yield strength of S2?
S2 has a typical yield strength of 460 MPa (66.7 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 55% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is S2 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed condition with sharp carbide or cobalt HSS at moderate speed; the ~1 % Si makes chips gummy, so use generous coolant and finish-grind after hardening.
Can S2 be welded?
Not readily — weldability is rated poor (15/100). Not a welding grade — repair only, with 200–320 °C preheat, matching or austenitic filler, and an immediate re-temper to avoid quench cracks.
What surface finishes work on S2?
Grind, then protect with black oxide, manganese phosphate or oil; thin electroplating requires post-plate bake (~190 °C) to avoid hydrogen embrittlement.
Can S2 be formed, bent or molded?
Forge 1010–1150 °C, never below ~900 °C, slow cool then anneal 760–790 °C; harden 845–885 °C with a severe water/brine quench (thin sections may be oil-quenched) and temper 175–370 °C for 50–60 HRC.
What is the maximum service temperature of S2?
S2 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does S2 cost?
S2 is a high-cost steel ($$$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in S2?
Yes — S2 is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A681 — Standard Specification for Tool Steels Alloy — ASTM International (2022)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (tool steels) — ASM International (1990)
- Tool Steels, 5th Edition (Roberts, Krauss, Kennedy) — ASM International (1998)
- Shock-resisting tool steel S2 data sheet — Tool-steel producers (Crucible/Böhler/Hudson-type datasheets) (2020)
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.