Steel S5
AISI/SAE S5 · UNS T41905
S5 (UNS T41905) is a silicon-manganese-molybdenum shock-resisting tool steel with high hardenability and toughness, supplied as annealed bar at about 215 HB (95 HRB).
Values for the Annealed condition
S5 tempers and conditions
S5 is supplied in 4 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft-annealed bar/plate as supplied | Standard stock condition for machining tools before hardening. | 440 | 725 | 25 | 215 HB | — |
900 °C, air cooled | Intermediate condition used to homogenize forgings before spheroidize annealing; not a service condition. | 800 | 1,250 | 10 | 40 HRC | 3.8 % IACS |
58–60 HRC (low temper ~175–205 °C) | Maximum hardness/wear condition for punches and shear blades where impact loads are moderate. | 1,850 | 2,150 | 4 | 59 HRC | — |
870 °C oil quench, untempered | Peak hardness before tempering; must be tempered immediately to avoid cracking. | 2,050 | 2,400 | 1 | 63 HRC | 3.5 % IACS |
What is S5?
S5 (UNS T41905) is a silicon-manganese-molybdenum shock-resisting tool steel with high hardenability and toughness, supplied as annealed bar at about 215 HB (95 HRB). It is used where tooling takes heavy impact — pneumatic chisels, punches and shear blades — and is oil-hardened from 870 °C and tempered at 175–425 °C to 50–60 HRC. Annealed properties are around 440 MPa yield, 725 MPa tensile and 25 % elongation; wear resistance and hot hardness are modest, service is limited to about 400 °C, and S7 is the usual air-hardening alternative for larger sections. S5 has a density of 7.76 g/cm³ (0.28 lb/in³), lighter than 92% of steel grades. It melts at 1,420°C (2,588 °F). S5 has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 50% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi).
What is S5 used for?
- Pneumatic chisels
- Punches
- Shear and cropping blades
- Rivet sets and chipping hammers
- Cold heading and stamping tooling
- Impact drivers and screwdriver bits
- Concrete breaker points
Advantages
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Poor heat conductor — 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Low electrical conductivity — 4 % IACS, worse than 83% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
S5 properties
Typical room-temperature values for S5-Annealed; bars are the position among steel grades.
Physical3
S5 has a density of 7.76 g/cm³ (0.28 lb/in³), lighter than 92% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
S5 has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 50% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
S5 is rated for continuous service to 400°C (752 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades. Thermal expansion is 12.4 µm/m·K (6.89 µin/in·°F).
Electrical3
S5 conducts electricity at 4 % IACS, worse than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of S5 takes about 36 MJ of energy and emits 2.6 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 40%.
Manufacturability8
S5's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (25/100); formability poor (30/100).
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. S5 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S5
Is S5 easy to machine?
Machine in the annealed condition (~215 HB) with sharp carbide or HSS tooling; the ~2% Si makes chips gummy, so use positive rake, rigid setups and flood coolant, and finish-grind after hardening.
Can S5 be welded?
Only repair welding is advised: preheat 300–350 °C, use matching or low-hydrogen electrodes, keep interpass heat, then temper immediately at the part's tempering temperature.
Can S5 be formed, bent or molded?
Hot forge 1040–1100 °C, stop above ~900 °C and slow-cool, then spheroidize anneal 760–790 °C; cold forming is limited to light bending in the annealed state.
Manufacturability
The process limits FabDigit applies to S5. Every S5 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair50 / 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 |
S5 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 | 0.5 – 0.65 | 0.58 |
| Sihigh Si gives the shock-resisting character | 1.75 – 2.25 | 2 |
| Mn | 0.6 – 1 | 0.8 |
| Mo | 0.2 – 1.35 | 0.4 |
| Croptional addition per ASTM A681 | ≤ 0.5 | 0.3 |
| Voptional, grain refinement | ≤ 0.35 | 0.2 |
| Niresidual | ≤ 0.3 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on S5?
Harden from 870 °C in oil (or interrupted/marquench), temper at 175–425 °C for 50–60 HRC; protect with black oxide, phosphate or oil — no anodizing, and avoid hard chrome above the temper temperature.
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 S5 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T41905
How much does S5 cost?
S5 is a premium-cost steel ($$$), pricier than about 57% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
S5 — frequently asked
What is S5 used for?
S5 is typically used for pneumatic chisels, punches, shear and cropping blades, rivet sets and chipping hammers, cold heading and stamping tooling and impact drivers and screwdriver bits. In short: shock-resistant tool steel.
What is the yield strength of S5?
S5 has a typical yield strength of 440 MPa (63.8 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 50% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is S5 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the annealed condition (~215 HB) with sharp carbide or HSS tooling; the ~2% Si makes chips gummy, so use positive rake, rigid setups and flood coolant, and finish-grind after hardening.
Can S5 be welded?
Not readily — weldability is rated poor (25/100). Only repair welding is advised: preheat 300–350 °C, use matching or low-hydrogen electrodes, keep interpass heat, then temper immediately at the part's tempering temperature.
What surface finishes work on S5?
Harden from 870 °C in oil (or interrupted/marquench), temper at 175–425 °C for 50–60 HRC; protect with black oxide, phosphate or oil — no anodizing, and avoid hard chrome above the temper temperature.
Can S5 be formed, bent or molded?
Hot forge 1040–1100 °C, stop above ~900 °C and slow-cool, then spheroidize anneal 760–790 °C; cold forming is limited to light bending in the annealed state.
What is the maximum service temperature of S5?
S5 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does S5 cost?
S5 is a premium-cost steel ($$$), pricier than about 57% 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 S5?
Yes — S5 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 (2015)
- 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)
- ASM Handbook Vol.16: Machining — ASM International (1989)
- MatWeb AISI S5 tool steel datasheets — MatWeb LLC (2024)
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.