1095 steel (G10950): properties, composition, equivalents
1095 steel (AISI/SAE 1095, UNS G10950): 0.95 % C high-carbon steel for knives, springs and blades. Hardens to 64–66 HRC; used at 56–60 HRC (blades) or 44–50 HRC (springs). Composition, heat treatment, 1095 vs 1084/O1/5160, C100S/SK4/CK101 equivalents.
What is 1095?
AISI 1095 is the highest-carbon member of the plain-carbon 10xx series: 0.90–1.03 % carbon with only 0.3–0.5 % manganese, UNS G10950. Above the eutectoid composition it forms excess cementite, which gives excellent edge retention and wear resistance after hardening to 64–66 HRC — the reason 1095 has been the standard American knife, sword, saw-blade and spring-clip steel for a century. Blades are tempered to 56–62 HRC; springs, clock springs and blue-tempered strip to 44–50 HRC.
Because it contains no alloying elements, hardenability is very low: a fast quench (brine or a fast quench oil) and thin sections (< 6 mm) are needed for full hardness, and the steel is unforgiving of slow quenches (pearlite forms in about one second). This makes 1095 easy to differentially harden — a clay-coated back stays soft while the edge hardens — but it also means 1095 is not a through-hardening steel for thick parts. Toughness is modest and corrosion resistance nil (blades rust without oil).
EN C100S (1.1274), JIS SK95 (SK4) and BS CS100 are the same steel; W1 tool steel is the tool-quality version; 1084 and 5160 are the tougher alternatives.
1095 chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | 0.9 – 1.03 | |
| Mn | 0.3 – 0.5 | |
| P | ≤ 0.04 | |
| S | ≤ 0.05 |
SAE J403 / ASTM A29 (G10950). Si ≈ 0.15–0.30 typical (not specified). Compare EN C100S (1.1274): C 0.95–1.05, Mn 0.30–0.60, Si 0.15–0.35; JIS SK4 (SK95): C 0.90–1.00; DIN Ck101.
1095 mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| Annealed (spheroidized) strip — typical | ≈ 380 (≈ 55.1) | ≈ 650 (≈ 94.3) | 13 | ≈ 190 HB (max 210) |
| Hot rolled bar — typical | ≈ 460 (≈ 66.7) | ≈ 965 (≈ 140.0) | 9 | ≈ 293 HB |
| Normalized (900 °C) — typical | ≈ 500 (≈ 72.5) | ≈ 1015 (≈ 147.2) | 9 | ≈ 293 HB |
| Blue-tempered spring strip (A682), 44–50 HRC — typical | ≈ 1100–1300 (≈ 159.5–188.5) | ≈ 1400–1700 (≈ 203.1–246.6) | 3 | 44–50 HRC |
| Q&T, tempered 540 °C (1000 °F) — typical | ≈ 690 (≈ 100.1) | ≈ 1000 (≈ 145.0) | 13 | ≈ 300 HB |
| Q&T, tempered 315 °C (600 °F) — typical | ≈ 950 (≈ 137.8) | ≈ 1250 (≈ 181.3) | 10 | ≈ 375 HB |
| Knife blade, tempered 175–230 °C (350–450 °F) | — | — | — | 58–62 HRC |
| As-quenched (brine/fast oil, 800 °C) | — | — | — | 64–66 HRC |
Typical values (ASM / strip-producer data). 1095 has very low hardenability (ideal critical diameter ≈ 15–20 mm in water); full hardness requires thin sections and fast quench (brine, Parks 50 or equivalent fast oil). Strip products are ordered by hardness (HRC / HV) rather than strength.
Impact toughness
1095 requires a minimum Charpy V-notch energy of 10 J at 20 °C (typical, Q&T 300 HB; blades at 60 HRC ≈ 5–10 J unnotched). Low toughness — 1095 is a wear/edge steel, not a shock steel; differential hardening or a 200–230 °C temper improves blade toughness. Not for low-temperature service.
1095 equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| CS100 | BS (superseded British) | Identical | BS 1449 CS100 carbon spring strip. |
| C100S | EN (European) | Identical | 1.1274 (EN 10132-4 spring strip): C 0.95–1.05, Mn 0.30–0.60, Si 0.15–0.35. |
| SK95 (SK4) | JIS (Japan) | Identical | JIS G4401 SK95: C 0.90–1.00, Mn 0.10–0.50 — the Japanese knife/saw grade; SK85 (SK5) is the 0.85 % C step. |
| W1 | AISI / SAE | Near | AISI W1 water-hardening tool steel at 0.95–1.05 % C is chemically the same, supplied to tool-steel cleanliness (ASTM A686). |
| 1084 / 1084 | AISI / SAE | Near | 0.84 % C: near-eutectoid, more forgiving heat treatment, slightly tougher — the beginner knifemaker's alternative. |
| C90S / C98S | EN (European) | Near | 1.1217 / 1.1233 — adjacent carbon steps in EN spring-strip grades. |
| T9A / T10A | GB/T (China) | Near | GB/T 1298 T10A: C 0.95–1.04, Mn ≤ 0.40 — Chinese carbon tool steel; T9A at 0.85–0.94. |
| U9A / U10A | GOST (Russia/CIS) | Near | GOST 1435 U10A: C 0.95–1.09, Mn 0.17–0.33 (tool steel); 65G/70S2A are the spring steels. |
| 5160 | AISI / SAE | Functional | 0.6 % C, 0.8 % Cr spring steel: far tougher, less edge retention — for swords, leaf springs and choppers. |
| O1 | AISI / SAE | Functional | Oil-hardening tool steel (1.2510): deeper hardening, better wear, easier quench — the tool-shop upgrade. |
| 52100 | AISI / SAE | Functional | Plain 0.95 % C: similar hardness, much lower hardenability, no chromium carbides — cheaper knife/spring alternative. |
Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for 1095 →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| C1095 | AISI (pre-1960s) | Still printed on knife blanks and saw blades. |
| G10950 | UNS | |
| CS95 / CS100 | BS 1449 (withdrawn) | Carbon spring strip. |
| Ck101 / C100S | DIN 17222 / EN 10132-4 | Cold-rolled spring strip. |
| SK4 / SK95 | JIS G4401 | SK4 (old) = SK95 (2000+). |
| W1 (near) | AISI tool steel | W1 (0.6–1.4 % C water-hardening tool steel) — the same steel with tool-steel quality control. |
Product forms and tolerance standards
Product forms: cold-rolled strip and flat stock (ASTM A684 / A682) — annealed or blue-tempered (hardened & tempered spring strip), hot-rolled and cold-drawn bar (A29, A108) — knife billets, wire (A228 music wire is a 0.8–0.95 C relative), plate (limited), flat ground stock for knifemakers.
Dimensional tolerances: strip: ASTM A684 (annealed) / A682 (tempered); thickness commonly ±0.025 mm; bar: ASTM A29 / A108.
Key property values
1095 hardness
As-quenched 64–66 HRC (thin sections, fast quench); knives tempered 175–230 °C → 58–62 HRC; springs and blue-tempered strip → 44–50 HRC; annealed (spheroidized) ≈ 190 HB (max 210); hot-rolled ≈ 293 HB.
1095 yield and tensile strength
Annealed ≈ 380 / 650 MPa; hot-rolled ≈ 460 / 965 MPa; Q&T tempered 540 °C ≈ 690 / 1000 MPa; tempered 315 °C ≈ 950 / 1250 MPa; blue-tempered spring strip ≈ 1100–1300 / 1400–1700 MPa.
Heat treatment
Spheroidize anneal 730–760 °C slow cool (for machining/forming). Normalize 870–900 °C (grain refinement after forging). Harden 790–815 °C (1450–1500 °F) — do not overheat (retained austenite, grain growth) — quench in brine or fast oil; thin blades can be water-quenched with care. Temper immediately: 175–230 °C for blades (58–62 HRC), 260–315 °C for chisels/punches (54–58 HRC), 370–450 °C for springs (44–50 HRC). Ac1 ≈ 725 °C, Acm ≈ 800 °C, Ms ≈ 215 °C. Quench must reach < 540 °C within ~1 s for full hardness.
Edge retention and toughness
Wear resistance among the best of the plain-carbon steels (fine cementite); toughness low (≈ 5–10 J unnotched at 60 HRC), improving markedly at 56–58 HRC. Differential hardening (clay/hamon) or a soft spine gives sword-grade toughness with a hard edge.
Corrosion resistance
None — plain carbon steel. Blades develop a patina and rust in humid storage; oil, wax or force a patina (vinegar/mustard) for protection.
Physical properties
Density 7.85 g/cm³, E = 205 GPa, expansion 11.4 × 10⁻⁶/K, conductivity ≈ 50 W/m·K.
Weldability
Not recommended (CE ≈ 1.0+). If unavoidable: preheat 300–400 °C, low-hydrogen filler, post-weld anneal at 730–760 °C, then re-harden. Forge-welding (damascus, san-mai) at 1100–1200 °C with flux is common in knifemaking; arc-welding of blades causes cracking.
Machining, forming and heat treatment
Machinability ≈ 40–45 % of B1112 in the spheroidized condition (hard cementite wears tools; use carbide, low speed). Machine, grind and drill in the annealed state only; after hardening only grinding (with coolant to avoid burning) and EDM are practical. Cold forming: bending of annealed strip to ≥ 2 t; hot forging 1050–850 °C followed by normalizing and spheroidizing. Surface treatments: black oxide, parkerizing, cerakote; no plating on hardened blades without hydrogen bake.
Typical applications
- Knife blades (fixed-blade, machetes, kukris), swords and axes
- Saw blades: hand saws, band and circular saw bodies, scrapers
- Flat and clock springs, spring clips, retaining rings, snap rings (blue-tempered strip)
- Cutting tools: chisels, punches, wood-working blades, shear blades (light duty)
- Agricultural blades: sickles, cutter bars, mower blades
- Music wire relatives (A228) for coil springs; needles, pins, feeler gauges
- Shim stock, doctor blades, feeler-gauge stock
Frequently asked questions
Is 1095 a good knife steel?
Yes for fixed-blade working knives: easy to sharpen, excellent edge retention among carbon steels, takes a very keen edge at 58–62 HRC and can be differentially hardened. Downsides: it rusts, has modest toughness at high hardness, and needs a fast quench that thin blades tolerate but thick ones do not.
What is the difference between 1095 and 1084?
Carbon: 0.95 vs 0.84 %. 1084 is near-eutectoid, so it hardens fully with a slower (safer) quench and is slightly tougher; 1095 holds an edge a little longer and reaches higher maximum hardness (66 vs 65 HRC) but is less forgiving in heat treatment. Beginners usually start with 1084.
How hard does 1095 get?
64–66 HRC as-quenched in thin sections with a brine or fast-oil quench. Knives are tempered to 58–62 HRC, springs to 44–50 HRC. Thick sections (> 6–8 mm) will not through-harden because of the very low hardenability.
What temperature do you heat-treat 1095 at?
Austenitize 790–815 °C (a dull cherry / just past non-magnetic), quench in brine or fast oil (must cool below ~540 °C within a second), temper immediately at 175–230 °C for blades (twice, 1–2 h each). Overheating above 850 °C causes grain growth and retained austenite.
What is 1095 equivalent to in EN and JIS?
EN C100S (1.1274, spring strip) and JIS SK95 (formerly SK4) are the same steel; DIN Ck101 and BS CS100 as well. AISI W1 tool steel is the tool-quality version.
Does 1095 rust?
Yes, readily — it has no chromium. Keep blades dry and oiled, or let them develop a stable patina; for corrosion resistance choose a stainless blade steel (440C, 154CM, VG-10, N690).
Related grades
Verified against ASTM A29/A29M-20 (SAE J403 chemistry); ASTM A29/A29M-20 Table 1 (G10950); ASTM A684/A684M and A682/A682M (strip); ASM Handbook Vol. 4 (heat treating); EN 10132-4:2021 (C100S comparison). Last checked: September 2026.