Materials & grades
S7 shock-resisting tool steel: nearest equivalents 50CrMoV13-15 (1.2355) and 1.2357
S7 is an air-hardening shock-resisting tool steel with about 0.5 % carbon, 3.25 % chromium and 1.4 % molybdenum that keeps high toughness at about 55–60 HRC, used for chisels, punches, heading dies and shear blades. It has no exact European, Indian or Japanese equivalent; 50CrMoV13-15 (1.2355) is the nearest European grade.
Names by standard
What it is called in each region
| Region | System | Designation | Standard | Match |
|---|---|---|---|---|
| USA | AISI / ASTM A681 type | S7 | ASTM A681 | Same material |
| UNS | T41907 | — | Same material | |
| UK | BS EN ISO 4957 | 50CrMoV13-15The UK adopts EN ISO 4957, so the nearest European grade applies. No BS 4659 name for S7 was found. | BS EN ISO 4957 | Closest equivalent |
| EU | EN 10027-1 name | 50CrMoV13-15Industeel gives 50CrMoV13-15 as the EURONORM name for S7 and Böhler describes K320 as 1.2355 (50CrMoV13-15, S7). It is listed in EN ISO 4957 (SteelNumber grade list, Total Materia). | EN ISO 4957 | Closest equivalent |
| EN 10027-2 number | 1.2355Material number given by Böhler and Industeel for S7-type steel. Böhler sells it as K320. | EN ISO 4957 | Closest equivalent | |
| DIN (legacy) | 50CrMoV13-14 (1.2357)Older German name with slightly less carbon. Böhler's data table shows ~1.2357 and ~50CrMoV13-14 beside S7; zknives and Total Materia also list it. | — | Closest equivalent | |
| India | IS 3748 | 50CrMoV13-15India adopts ISO 4957 identically as IS 3748:2022, so the nearest ISO grade applies. | IS 3748:2022 (identical to ISO 4957) | Closest equivalent |
On equivalence
- No exact equivalent exists outside the US. Industeel maps S7 to 50CrMoV13-15 (≈1.2355). Böhler describes K320 as 1.2355 (50CrMoV13-15, S7) but prints ~1.2357 and ~50CrMoV13-14 in its data table, marking them approximate. Treat both as closest, not equivalent.
- 50CrMoV13-14 (1.2357) is the older DIN name with 0.50 % carbon typical and 3.25–3.30 % chromium; its published analyses differ slightly between sources.
- S7 carbon is 0.45–0.55 % (A681); Crucible's typical is 0.55 % while Böhler K320 is 0.53 % and Industeel 0.50 %.
- No JIS G 4404 grade or BS 4659 name is linked to S7 in the sources reviewed. The UK and India adopt ISO 4957, so 50CrMoV13-15 is their nearest grade too.
- S7 is not a hot-work steel, although it is used in warm shock applications. For hot work see H13.
Chemical composition
Composition limits, mass %
| Element | S7 (T41907)USA · ASTM A681-08 (includes product analysis tolerances) | 50CrMoV13-15 (≈1.2355)EU · Industeel S7 data sheet (EURONORM 50CrMoV13-15, mill limits) |
|---|---|---|
| C | 0.45–0.55 | 0.48–0.55 |
| Si | 0.20–1.00 | — |
| Mn | 0.20–0.90 | 0.60–0.90 |
| P | ≤0.030 | — |
| S | ≤0.030 | — |
| Cr | 3.00–3.50 | 3.00–3.50 |
| Mo | 1.30–1.80 | 1.30–1.55 |
| V | ≤0.35 | 0.20–0.35 |
| Ni+Cu | ≤0.75 | — |
Mechanical properties
Strength and hardness
| Condition | Tensile strength | Yield strength | Elongation | Hardness |
|---|---|---|---|---|
| Annealed (ASTM A681)Specified maximum; cold-drawn bar may be up to 255 HBASTM A681-08, Table 2 | — | — | — | ≤229 HB |
| Annealed (mill delivery)Typical mill maximumMill data sheets listed under sources | — | — | — | ≤225 HB (Böhler K320 and Industeel); about 187–220 HB (Crucible) |
| Hardened and tempered, response test (ASTM A681)Specified minimum after austenitizing at 941–954 °C (1725–1750 °F), air quench, one 2-hour temper at 204 °C (400 °F)ASTM A681-08, Table 3 | — | — | — | ≥56 HRC |
| As air quenchedTypical, austenitized 940 °C (1725 °F)Crucible S7 data sheet | — | — | — | 59–61 HRC |
| Tempered at 205–315 °CTypical, austenitized 940 °C, air cooledCrucible S7 data sheet | — | — | — | 55–58 HRC at 205 °C, 54–56 HRC at 260 °C, 53–55 HRC at 315 °C |
| Tempered at 370–540 °CTypical, austenitized 940 °C, air cooledCrucible S7 data sheet | — | — | — | 52–54 HRC at 370–425 °C, 51–53 HRC at 480 °C, 50–52 HRC at 540 °C |
| Tempered at 595–705 °CTypical, austenitized 940 °C, air cooledCrucible S7 data sheet | — | — | — | 46–48 HRC at 595 °C, 40–42 HRC at 650 °C, 33–35 HRC at 705 °C |
| Impact toughness, Charpy C-notchTypical, tempered to 57 HRC after austenitizing at 955 °C (1750 °F). For comparison, D2 at 60 HRC gives about 28 J and A2 at 60 HRC about 53 J.Crucible S7 data sheet | — | — | — | 57 HRC, about 169 J (125 ft-lb) |
In practice
Behaviour, heat treatment and uses
Characteristics
- Designed for high impact and shock resistance at relatively high hardness: about 57 HRC with a Charpy C-notch value of 125 ft-lb (169 J), far above D2, A2 or O1 at 60 HRC (Crucible).
- Wear resistance is low to medium. Crucible's crossed-cylinder adhesive-wear index is 1 for S7 against 2–4 for A2 and D2.
- Deep hardening and air quenching with minimal distortion, except in large sections (over about 75 mm) where an interrupted oil quench may be needed (Crucible).
- Easy to machine annealed: about 75 % of W1 tool steel (Crucible). Böhler rates toughness, wear resistance, compressive strength and dimensional stability as good.
- Used for both cold and warm shock applications. Size change on hardening is about +0.10 % (air cooled from 940–955 °C and tempered at 205 °C, Crucible).
- Not normally nitrided, because the tempering temperature needed before nitriding costs hardness (Crucible).
Heat treatment
- Annealing: about 820–850 °C (1510–1560 °F) (Böhler); Crucible gives 845 °C (1550 °F), 2 hours, then furnace cool 30 °C per hour to 540 °C and air.
- Stress relieving: annealed parts at 650–675 °C (1200–1250 °F), 2 hours, air cool; hardened parts 15–30 °C below the last temper (Crucible).
- Preheat 730–760 °C, then austenitize at 940–955 °C (1725–1750 °F), 30–45 minutes (Crucible). Böhler gives 930–950 °C and Industeel 940 °C.
- Quench: air, positive-pressure gas (2 bar minimum) or interrupted oil to below 65 °C for sections over about 75 mm. Böhler also allows oil.
- Tempering: 205–540 °C depending on the hardness required. At least 2 hours or 1 hour per 25 mm. Double tempering is recommended, with cooling to room temperature between tempers (Crucible, Industeel).
Typical uses
- Chisels and punches under shock loading
- Shear blades and shear knives
- Cold and warm heading dies
- Blanking and forming dies
- Hobbed dies and small plastic moulds
- Tablet compression and zinc die-casting dies
- Backing and support plates
Tool steels
Similar grades compared
| Grade | C % | Mn % | Cr % | Ni % | Tensile, first listed condition |
|---|---|---|---|---|---|
| S7 | 0.45–0.55 | 0.20–0.90 | 3.00–3.50 | — | — |
| A2 / 1.2363 | 0.95–1.05 | 0.40–1.00 | 4.75–5.50 | — | — |
| D2 / 1.2379 | 1.40–1.60 | 0.10–0.60 | 11.00–13.00 | — | — |
| D3 / 1.2080 | 2.00–2.35 | 0.10–0.60 | 11.00–13.50 | — | — |
| O1 / 1.2510 | 0.85–1.00 | 1.00–1.40 | 0.40–0.70 | — | — |
| H11 / 1.2343 | 0.33–0.43 | 0.20–0.50 | 4.75–5.50 | — | 1790–1845 MPa |
| H13 / 1.2344 | 0.32–0.45 | 0.20–0.60 | 4.75–5.50 | — | 1730–1845 MPa |
| M2 / HS6-5-2C | 0.78–0.88 | 0.15–0.40 | 3.75–4.50 | — | ≤950 MPa |
| M42 / HS2-9-1-8 | 1.05–1.15 | 0.15–0.40 | 3.50–4.25 | — | ≤1010 MPa |
| P20 / 1.2311 | 0.28–0.40 | 0.60–1.00 | 1.40–2.00 | 0.90–1.20 | 950–1100 MPa |
Composition from the US standard where one exists, otherwise the first standard listed on each grade's page. Strength conditions differ between grades; open a grade for its full table.
Questions answered
Common questions
What is the equivalent of S7 tool steel?
The nearest European grade is 50CrMoV13-15 (1.2355), which the UK (BS EN ISO 4957) and India (IS 3748:2022) also use; the older DIN 50CrMoV13-14 (1.2357) is also quoted. None is an exact match, and no JIS grade is linked to S7.
What is S7 tool steel used for?
Parts that take heavy impact: chisels, punches, shear blades, heading dies and small plastic moulds. It stays tough at about 57 HRC, where D2 or A2 would chip.
Is S7 air hardening?
Yes. ASTM A681 tests S7 with an air quench from 941–954 °C. Sections over about 75 mm may need an interrupted oil quench (Crucible).
S7 or H13: which is tougher?
At working hardness S7 is used harder: Crucible lists S7 at 57 HRC and H13 at 46 HRC. H13 is the better choice for elevated-temperature work because it holds hardness when hot.
What hardness does S7 reach?
About 59–61 HRC as air quenched and 55–58 HRC after a 205 °C temper. ASTM A681 requires at least 56 HRC after air hardening and a 204 °C temper.
From the Corona catalog
Need a part made to this specification?
Send the drawing, the material or grade, the finish, the quantity and the delivery country. The team reviews the requirement and the manufacturing route.
Start an enquiryKeep reading
Related references
References
Sources
- ASTM A681-08 Standard Specification for Tool Steels Alloy (copy hosted by Fushun Special Steel) — Table 1 composition, Table 2 annealed hardness, Table 3 response to hardening. 2008 edition; check the current revision.
- Crucible S7 data sheet (AISI S7) — Typical composition, tempering and impact table, size change, heat treatment, comparison with H13, O1, A2, D2.
- Böhler K320 data sheet (voestalpine) — 1.2355 (50CrMoV13-15, S7); data table ~1.2357 / ~50CrMoV13-14 / S7; annealed 225 HB max; hardening 930–950 °C.
- Industeel (ArcelorMittal): AISI S7 data sheet — EURONORM 50CrMoV13-15, ≈1.2355, ASTM A681 S7; mill composition limits; annealed 225 HB max.
- SteelNumber: EN ISO 4957 grade list (includes 1.2355 50CrMoV13-15) — Independent check: lists 1.2355 50CrMoV13-15 and 1.2825 95MnWCr5 but not 100MnCrW4.
- Total Materia: DIN 50CrMoV13-15 (EN ISO 4957:2018) — Independent check: tool steel under EN ISO 4957:2018, equivalents include EN 1.2355 and B.S. 50CrMoV13-15.
- Zknives: AISI S7 designations — Lists DIN 50CrMoV13-14, W-Nr 1.2357, UNS T41907; no BS, IS, JIS or EN entry.
- Total Materia: DIN 50 CrMoV 13-14 tool steel — Older DIN listing for the 1.2357 grade.
Values summarize published limits and typical data. The governing standard and the current edition control; check them before specifying.