Steel S15CK
JIS S15CK
S15CK is a JIS plain low-carbon carbon steel supplied as a carburizing grade for economical light-duty case-hardened parts.
Reference datasheet — S15CK 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 HR condition
S15CK tempers and conditions
S15CK is supplied in 7 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Wire/bar for cold forging and cold heading of pins, bolts and shafts before carburizing. | 220 | 370 | 38 | 105 HB | 11 % IACS |
Solution annealed | Softest condition; choose for maximum ductility before deep drawing or heavy machining. | 235 | 390 | 36 | 111 HB | 10.8 % IACS |
HRDefault Hot rolled | Standard stock condition for carburizing blanks; machine then case harden. | 255 | 420 | 32 | 121 HB | — |
Normalized | Uniform fine-grain structure before carburizing; reduces distortion and improves machined finish. | 275 | 450 | 32 | 126 HB | 10.8 % IACS |
Quenched and tempered | Rarely used for this low-carbon grade; only for thin sections where modest core strength gain is wanted without carburizing. | 350 | 500 | 26 | 160 HB | 10.5 % IACS |
Carburized + quenched & tempered | The functional service condition: hard wear-resistant case (0.3–1.0 mm) over a tough soft core for light-duty pins, bushings and small gears. | 390 | 560 | 25 | 60 HRC | — |
Cold drawn | Pick for close tolerance, bright surface and better chip control on turned pins and shafts. | 440 | 520 | 15 | 149 HB | — |
What is S15CK?
S15CK is a JIS plain low-carbon carbon steel supplied as a carburizing grade for economical light-duty case-hardened parts. In the default condition it provides 255 MPa yield, 420 MPa tensile, 32% elongation and about 121 HB (68 HRB), with machinability around 50% of AISI 1212; stock is available hot rolled, annealed, spheroidized, normalized, cold drawn and in carburized or quenched-and-tempered conditions. Core strength is low and the steel has no corrosion resistance, so it suits pins and bushings rather than heavily loaded gears. S20CK gives slightly higher core strength, and SCM415 or 15CrNi6 are the step up for alloyed cases. S15CK has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 90% of steel grades. It melts at 1,495°C (2,723 °F). S15CK has a yield strength of 255 MPa (37 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 93% of steel grades. Elongation at break is 32% and the elastic modulus is 205 GPa (29.7 Msi).
What is S15CK used for?
- pins
- light gears
- bushings
Advantages
- Readily welded — 95/100, better than 97% of steel grades
- Forms and bends easily — 85/100, better than 96% of steel grades
- Ductile — tolerates forming and impact — 32%, better than 95% of steel grades
- High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
- Conducts heat well — 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades
Limitations
- Low strength — 255 MPa (37 ksi), worse than 93% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
S15CK properties
Typical room-temperature values for S15CK-HR; bars are the position among steel grades.
Physical3
S15CK has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 90% of steel grades. It melts at 1,495°C (2,723 °F).
Mechanical16
S15CK has a yield strength of 255 MPa (37 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 93% of steel grades. Elongation at break is 32% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
S15CK is rated for continuous service to 400°C (752 °F). It conducts heat at 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
S15CK conducts electricity at 10.8 % IACS, better than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of S15CK takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
S15CK's machinability is fair (50/100, worse than 53% of steel grades); weldability excellent (95/100); formability excellent (85/100).
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. S15CK is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S15CK
Is S15CK easy to machine?
Soft and gummy — use sharp positive-rake tools, high speed with coolant and chip-breaking geometry, or specify cold-drawn/normalized stock for cleaner finishes.
Can S15CK be welded?
Excellent weldability by all arc, resistance and gas processes with no preheat; avoid welding after carburizing since the hard case cracks and decarburizes.
Can S15CK be formed, bent or molded?
Very good cold formability — suits cold heading, upsetting, deep drawing and bending; hot forge 1100–1250 °C, then normalize before carburizing.
S15CK 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 | 0.13 – 0.18 | 0.16 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.3 – 0.6 | 0.45 |
| Ptighter than non-K grades | ≤ 0.03 | |
| Stighter than non-K grades | ≤ 0.03 | |
| Curesidual | ≤ 0.2 | |
| Niresidual; Ni+Cr ≤ 0.30 | ≤ 0.2 | |
| Crresidual; Ni+Cr ≤ 0.30 | ≤ 0.2 | |
| Fe | balance |
What surface finishes work on S15CK?
No corrosion resistance in itself: finish with zinc or nickel plating, black oxide, phosphate + oil, or paint; carburized parts should be plated with low-hydrogen processes and baked to avoid embrittlement.
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
How much does S15CK cost?
S15CK is a budget-cost steel ($), cheaper than about 90% 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.
S15CK — frequently asked
What is S15CK used for?
S15CK is typically used for pins, light gears and bushings. In short: low-cost carburizing carbon steel; excellent weldability; light-duty case-hardened parts.
What is the yield strength of S15CK?
S15CK has a typical yield strength of 255 MPa (37 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 93% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is S15CK easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Soft and gummy — use sharp positive-rake tools, high speed with coolant and chip-breaking geometry, or specify cold-drawn/normalized stock for cleaner finishes.
Can S15CK be welded?
Yes — weldability is rated excellent (95/100). Excellent weldability by all arc, resistance and gas processes with no preheat; avoid welding after carburizing since the hard case cracks and decarburizes.
What surface finishes work on S15CK?
No corrosion resistance in itself: finish with zinc or nickel plating, black oxide, phosphate + oil, or paint; carburized parts should be plated with low-hydrogen processes and baked to avoid embrittlement.
Can S15CK be formed, bent or molded?
Very good cold formability — suits cold heading, upsetting, deep drawing and bending; hot forge 1100–1250 °C, then normalize before carburizing.
What is the maximum service temperature of S15CK?
S15CK 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.
What is the difference between S15CK-HR and S15CK-CD?
HR is the default condition — standard stock condition for carburizing blanks; machine then case harden. CD: pick for close tolerance, bright surface and better chip control on turned pins and shafts. Yield strength is 255 MPa in HR versus 440 MPa in CD.
How much does S15CK cost?
S15CK is a budget-cost steel ($), cheaper than about 90% 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
- JIS G 4051 — Carbon steels for machine structural use — JISC (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- GB/T 699 — Quality carbon structural steels (15 steel) — SAC (2015)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals (carburizing) — ASM International (2013)
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.