Steel S6
AISI/SAE S6 · UNS T41906
S6 is a chromium-silicon-molybdenum shock-resisting tool steel (T41906) in the AISI S group, where about 2 % Si with Cr and Mo combines high toughness with better abrasion resistance than the plain silicon S grades.
Reference datasheet — S6 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ANN condition
S6 tempers and conditions
S6 is supplied in 6 conditions, soft to hard. ANN 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 |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard mill supply condition for bar and flats; machine and drill in this state before hardening. | 415 | 740 | 22 | 210 HB | — |
Hot rolled | Mill hot-worked stock before spheroidize annealing; only for re-forging or stock that will be fully heat treated. | 680 | 1,000 | 12 | 32 HRC | 3 % IACS |
Q&T 50–54 HRC | Pick when shock and chipping resistance outrank wear — heavy pneumatic tools, hot punches, shear knives on thick stock. | 1,400 | 1,700 | 10 | 52 HRC | — |
Q&T 54–56 HRC | Best all-round balance of toughness and wear for chisels, rivet sets and impact punches. | 1,550 | 1,900 | 7 | 55 HRC | — |
Q&T 56–58 HRC | Choose for punches and shear blades where abrasion dominates and impact energy is moderate. | 1,700 | 2,050 | 5 | 57 HRC | — |
Hardened, as-quenched | As-quenched martensite — an intermediate state only; must be tempered immediately to avoid cracking. | 1,800 | 2,200 | 1 | 61 HRC | 2.7 % IACS |
What is S6?
S6 is a chromium-silicon-molybdenum shock-resisting tool steel (T41906) in the AISI S group, where about 2 % Si with Cr and Mo combines high toughness with better abrasion resistance than the plain silicon S grades. Annealed stock is near 210 HB (415 MPa yield, 740 MPa tensile, 22 % elongation) and is oil hardened and double tempered to 50-58 HRC for tools under heavy impact. It has no corrosion resistance, decarburizes strongly during austenitizing, is not a structural weld grade, and service is limited to 200 °C; S7 is the common alternative when air hardening and simpler heat treatment matter. S6 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 93% of steel grades. It melts at 1,420°C (2,588 °F). S6 has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 740 MPa (107 ksi) — weaker than 56% of steel grades. Elongation at break is 22% and the elastic modulus is 207 GPa (30 Msi).
What is S6 used for?
- Chisels
- Heavy-duty punches
- Shear blades
- Forming tools
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Low electrical conductivity — 3 % IACS, worse than 91% of steel grades
- Poor heat conductor — 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
S6 properties
Typical room-temperature values for S6-ANN; bars are the position among steel grades.
Physical3
S6 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 93% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
S6 has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 740 MPa (107 ksi) — weaker than 56% of steel grades. Elongation at break is 22% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
S6 is rated for continuous service to 200°C (392 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades. Thermal expansion is 12.4 µm/m·K (6.89 µin/in·°F).
Electrical3
S6 conducts electricity at 3 % IACS, worse than 91% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of S6 takes about 33 MJ of energy and emits 2.4 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 40%.
Manufacturability7
S6's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (20/100); 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. S6 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S6
Is S6 easy to machine?
Machine only in the annealed state (≈200 HB); the 2 % Si makes chips gummy — use sharp carbide or cobalt HSS, rigid setups, and finish-grind after hardening.
Can S6 be welded?
Not a structural weld grade; repair-weld only with matching or S-series filler at 300–400 °C preheat followed by an immediate full temper.
Can S6 be formed, bent or molded?
Forge 1040–1150 °C, stop above 900 °C, cool slowly and spheroidize anneal at 780–800 °C; cold forming is limited to light bending of annealed strip.
S6 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 – 0.5 | 0.45 |
| Mn | 1.2 – 1.5 | 1.35 |
| Sihigh Si raises tempering resistance and hardenability; promotes decarburization | 2 – 2.5 | 2.25 |
| Cr | 1.2 – 1.5 | 1.35 |
| Mo | 0.3 – 0.5 | 0.4 |
| Vgrain refinement | 0.2 – 0.3 | 0.25 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on S6?
Harden 900–925 °C with a protective/neutral atmosphere or pack to control the strong decarburization tendency, oil quench, temper twice; finish with grinding plus black oxide, phosphate or nitride for rust protection.
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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel S6 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T41906
How much does S6 cost?
S6 is a premium-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.
S6 — frequently asked
What is S6 used for?
S6 is typically used for chisels, heavy-duty punches, shear blades and forming tools. In short: toughest wear-resisting S grade; oil-hardening impact steel; strong decarburization tendency.
What is the yield strength of S6?
S6 has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 740 MPa (107 ksi) — weaker than 56% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is S6 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine only in the annealed state (≈200 HB); the 2 % Si makes chips gummy — use sharp carbide or cobalt HSS, rigid setups, and finish-grind after hardening.
Can S6 be welded?
Not readily — weldability is rated poor (20/100). Not a structural weld grade; repair-weld only with matching or S-series filler at 300–400 °C preheat followed by an immediate full temper.
What surface finishes work on S6?
Harden 900–925 °C with a protective/neutral atmosphere or pack to control the strong decarburization tendency, oil quench, temper twice; finish with grinding plus black oxide, phosphate or nitride for rust protection.
Can S6 be formed, bent or molded?
Forge 1040–1150 °C, stop above 900 °C, cool slowly and spheroidize anneal at 780–800 °C; cold forming is limited to light bending of annealed strip.
What is the maximum service temperature of S6?
S6 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S6-ANN and S6 HT-AQ?
ANN is the default condition — standard mill supply condition for bar and flats; machine and drill in this state before hardening. HT-AQ: as-quenched martensite — an intermediate state only; must be tempered immediately to avoid cracking. Yield strength is 415 MPa in ANN versus 1,800 MPa in HT-AQ.
How much does S6 cost?
S6 is a premium-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.
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 ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- SAE J438 / UNS T41906 designation data — SAE International (2017)
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.