Steel S7
AISI/SAE S7 · UNS T41907 · EN 1.2355, 50CrMoV13-15
S7 is an air-hardening Cr-Mo-V shock-resisting tool steel from the ASTM A681 S group (1.2355 / 50CrMoV13-15 / T41907), pairing very high toughness and resistance to impact chipping with 54–58 HRC working hardness.
Values for the Annealed condition
S7 tempers and conditions
S7 is supplied in 6 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft, as-supplied bar/plate for machining | Standard stocked condition: machine, then harden and temper. | 530 | 830 | 18 | 15 HRC | 2.9 % IACS |
Hardened & Tempered 50–52 HRC | Choose when impact and gross shock dominate (heavy shear knives, forming dies, tooling for warm work). | 1,450 | 1,750 | 9 | 51 HRC | — |
austenitize 925–955 °C, air quench, temper (general) | Generic in-service condition when a specific hardness band is not called out. | 1,600 | 2,000 | 6 | 56 HRC | — |
case ~900–1100 HV | Add when surface wear or galling limits tool life; core properties stay those of the tempered condition. | 1,600 | 1,950 | 6 | 55 HRC | 2.7 % IACS |
Hardened & Tempered 54–56 HRC | Balanced hardness/toughness band most used for cold punches, chisels and rivet sets. | 1,650 | 2,000 | 6 | 55 HRC | — |
Hardened & Tempered 56–58 HRC | Maximum wear/indentation resistance for punches and shear blades where loads are not severely shock-loaded. | 1,750 | 2,150 | 4 | 57 HRC | — |
What is S7?
S7 is an air-hardening Cr-Mo-V shock-resisting tool steel from the ASTM A681 S group (1.2355 / 50CrMoV13-15 / T41907), pairing very high toughness and resistance to impact chipping with 54–58 HRC working hardness. Typical parts are punches, shear blades, rivet sets, cold and warm forging dies, plastic mould inserts and pneumatic tool components, where air quenching keeps distortion and cracking risk low in heavy sections. Wear resistance and hot hardness are clearly below D2, A2 and H13, and the steel does not resist corrosion; A2 or D2 is the better choice where abrasive wear dominates. S7 has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F). S7 has a yield strength of 530 MPa (76.9 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 69% of steel grades. Elongation at break is 18% and the elastic modulus is 207 GPa (30 Msi).
What is S7 used for?
- Jackhammer bits
- Rivet sets
- Punches
Advantages
- Polishes to a fine finish — 75/100, better than 94% of steel grades
- High service temperature — 500°C (932 °F), better than 90% of steel grades
Limitations
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- High embodied carbon — 2.7 kg CO₂/kg, worse than 89% of steel grades
- Poor heat conductor — 26 W/m·K (15 BTU/hr·ft·°F), worse than 87% of steel grades
S7 properties
Typical room-temperature values for S7-Annealed; bars are the position among steel grades.
Physical3
S7 has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical17
S7 has a yield strength of 530 MPa (76.9 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 69% of steel grades. Elongation at break is 18% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
S7 is rated for continuous service to 500°C (932 °F). It conducts heat at 26 W/m·K (15 BTU/hr·ft·°F), worse than 87% of steel grades. Thermal expansion is 12.6 µm/m·K (7 µin/in·°F).
Electrical3
S7 conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of S7 takes about 36 MJ of energy and emits 2.7 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 40%.
Manufacturability7
S7's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (30/100); 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. S7 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S7
Is S7 easy to machine?
Machine in the annealed condition (~200 HB) with rigid setups and moderate speeds; leave 0.3–0.8 mm for finish grinding after hardening since air quench still moves parts slightly.
Can S7 be welded?
Weld only for repair: preheat 200–320 °C, use matching or Cr-Mo tool-steel filler, keep interpass temperature and temper immediately at 15–30 °C below the original tempering temperature.
Can S7 be formed, bent or molded?
Hot work at 1050–900 °C with slow cooling and a full anneal (~800–830 °C, slow cool) afterwards; austenitize 925–955 °C, air quench in still air, double temper 205–480 °C to the target hardness.
Manufacturability
The process limits FabDigit applies to S7. Every S7 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 |
S7 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 | 0.45 – 0.55 | 0.5 |
| Si | 0.2 – 1 | 0.4 |
| Mn | 0.2 – 0.9 | 0.7 |
| Cr | 3 – 3.5 | 3.25 |
| Mo | 1.3 – 1.8 | 1.4 |
| Voptional; 1.2355 typically ~0.2 V | ≤ 0.35 | 0.25 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on S7?
Takes a good mold polish when hardened; protect the non-stainless surface with black oxide, phosphate, hard chrome, nitriding or PVD, and oil parts in storage.
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 S7 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T41907
- EN / DIN / Werkstoff-Nr.
- 1.235550CrMoV13-15
How much does S7 cost?
S7 is a specialty-cost steel ($$$$$), pricier than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
S7 — frequently asked
What is S7 used for?
S7 is typically used for jackhammer bits, rivet sets and punches. In short: extreme shock resistance.
What is the yield strength of S7?
S7 has a typical yield strength of 530 MPa (76.9 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 69% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is S7 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the annealed condition (~200 HB) with rigid setups and moderate speeds; leave 0.3–0.8 mm for finish grinding after hardening since air quench still moves parts slightly.
Can S7 be welded?
Not readily — weldability is rated poor (30/100). Weld only for repair: preheat 200–320 °C, use matching or Cr-Mo tool-steel filler, keep interpass temperature and temper immediately at 15–30 °C below the original tempering temperature.
What surface finishes work on S7?
Takes a good mold polish when hardened; protect the non-stainless surface with black oxide, phosphate, hard chrome, nitriding or PVD, and oil parts in storage.
Can S7 be formed, bent or molded?
Hot work at 1050–900 °C with slow cooling and a full anneal (~800–830 °C, slow cool) afterwards; austenitize 925–955 °C, air quench in still air, double temper 205–480 °C to the target hardness.
What is the maximum service temperature of S7?
S7 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does S7 cost?
S7 is a specialty-cost steel ($$$$$), pricier than about 58% 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 S7?
Yes — S7 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 — Alloy Tool Steels — ASTM International (2015)
- EN ISO 4957 / DIN 1.2355 (50CrMoV13-15) — CEN / DIN (2018)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Specialty Handbook: Tool Materials — ASM International (1995)
- S7 shock-resisting tool steel datasheets — Crucible / Böhler-Uddeholm / Hudson Tool Steel (2022)
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.