Steel S20C
JIS S20C
S20C is a low-carbon quality structural steel to JIS G4051 with 0.18–0.23 % C, broadly interchangeable with AISI 1020 and 20 steel.
Values for the CD condition
S20C tempers and conditions
S20C is supplied in 7 conditions, soft to hard. CD 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 |
|---|---|---|---|---|---|---|
Solution annealed | Softest, most ductile state — pick for deep drawing, severe cold bending or before carburizing. | 240 | 395 | 34 | 111 HB | — |
Hot rolled | Cheapest form for welded structures and parts to be fully machined or later heat treated. | 260 | 420 | 30 | 121 HB | — |
Normalized | Uniform fine grain and predictable properties — the condition JIS specifies minimum strengths against (≥402 MPa UTS). | 280 | 450 | 30 | 131 HB | — |
Cold drawn, stress relieved | Use when machined parts must stay straight — residual stress removed at ~550–650 °C with only small strength loss. | 350 | 470 | 18 | 137 HB | — |
CDDefault Cold drawn | Default stocked form: higher strength, tight tolerance and good surface for shafts, pins and turned parts. | 400 | 500 | 14 | 143 HB | — |
Carburized, quenched and low-temperature tempered | Choose for wear surfaces (gears, pins, bushings): hard 0.5–1.2 mm case on a tough, low-strength core. | 400 | 600 | 15 | 60 HRC | — |
Quenched and tempered | Only worth it on small sections — low carbon limits hardenability, giving modest strength gains over normalizing. | 420 | 560 | 22 | 170 HB | — |
What is S20C?
S20C is a low-carbon quality structural steel to JIS G4051 with 0.18–0.23 % C, broadly interchangeable with AISI 1020 and 20 steel. It is chosen for weldability, cold formability and low cost in general machine parts, brackets and welded assemblies, and for carburized parts needing a hard case over a tough core; cold-drawn bar gives about 400 MPa yield, 500 MPa tensile, 14 % elongation and 143 HB (78 HRB). Limits are poor atmospheric and fresh-water corrosion resistance, limited response to direct quenching, and low hardenability in heavy sections. Use S45C where higher through-hardened strength is required. S20C has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 90% of steel grades. It melts at 1,490°C (2,714 °F). S20C has a yield strength of 400 MPa (58 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 60% of steel grades. Elongation at break is 14% and the elastic modulus is 205 GPa (29.7 Msi).
What is S20C used for?
- General fabrication
- Brackets
- Welded plate
Advantages
- Conducts heat well — 51.9 W/m·K (30 BTU/hr·ft·°F), better than 96% of steel grades
- High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
- Readily welded — 92/100, better than 93% of steel grades
Limitations
- Limited ductility — 14%, worse than 75% of steel grades
S20C properties
Typical room-temperature values for S20C-CD; bars are the position among steel grades.
Physical3
S20C has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 90% of steel grades. It melts at 1,490°C (2,714 °F).
Mechanical16
S20C has a yield strength of 400 MPa (58 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 60% of steel grades. Elongation at break is 14% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
S20C is rated for continuous service to 400°C (752 °F). It conducts heat at 51.9 W/m·K (30 BTU/hr·ft·°F), better than 96% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
S20C 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 S20C takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability8
S20C's machinability is good (58/100, better than 75% of steel grades); weldability excellent (92/100); formability good (60/100).
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. S20C is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S20C
Is S20C easy to machine?
Free machining at moderate speeds but gummy in the annealed state — cold-drawn bar, positive rake and sharp tooling give the best finish; expect burrs.
Can S20C be welded?
Excellent weldability by all arc processes with no preheat up to ~25 mm; carbon equivalent ≈ 0.3, use E70xx/ER70S-x filler.
Can S20C be formed, bent or molded?
Bends, headers and stamps readily when annealed or hot rolled; cold-drawn bar needs generous bend radii or intermediate anneal.
Manufacturability
The process limits FabDigit applies to S20C. Every S20C part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better58 / 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 |
Sheet metal
| Formability | Excellent60 / 100 |
|---|---|
| Weldability | Excellent92 / 100 |
S20C 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 | 0.18 – 0.23 | 0.2 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.03 | |
| S | ≤ 0.04 | |
| Curesidual, max | ≤ 0.3 | |
| Niresidual, max | ≤ 0.2 | |
| Crresidual, max; Ni+Cr ≤ 0.35 | ≤ 0.2 | |
| Fe | balance |
What surface finishes work on S20C?
Not anodizable — protect by zinc plating, black oxide, phosphate + oil, nitrocarburizing or paint; carburize and grind where wear resistance is needed.
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 S20C in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Other
- 1020
How much does S20C cost?
S20C is a budget-cost steel ($), cheaper than about 100% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
S20C — frequently asked
What is S20C used for?
S20C is typically used for general fabrication, brackets and welded plate. In short: cold-drawn machining bar.
What is the yield strength of S20C?
S20C has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is S20C easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Free machining at moderate speeds but gummy in the annealed state — cold-drawn bar, positive rake and sharp tooling give the best finish; expect burrs.
Can S20C be welded?
Yes — weldability is rated excellent (92/100). Excellent weldability by all arc processes with no preheat up to ~25 mm; carbon equivalent ≈ 0.3, use E70xx/ER70S-x filler.
What surface finishes work on S20C?
Not anodizable — protect by zinc plating, black oxide, phosphate + oil, nitrocarburizing or paint; carburize and grind where wear resistance is needed.
Can S20C be formed, bent or molded?
Bends, headers and stamps readily when annealed or hot rolled; cold-drawn bar needs generous bend radii or intermediate anneal.
What is the maximum service temperature of S20C?
S20C is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S20C-CD and S20C-A?
CD is the default condition — default stocked form: higher strength, tight tolerance and good surface for shafts, pins and turned parts. A: softest, most ductile state — pick for deep drawing, severe cold bending or before carburizing. Yield strength is 400 MPa in CD versus 240 MPa in A.
How much does S20C cost?
S20C is a budget-cost steel ($), cheaper than about 100% 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 S20C?
Yes — S20C is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- JIS G 4051 — Carbon steels for machine structural use — JISC (2016)
- GB/T 699 — Quality carbon structural steels (20 steel) — SAC (2015)
- ASTM A108 / SAE J403 (1020) — ASTM / SAE (2018)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19: Fatigue and Fracture — ASM International (1996)
- worldsteel LCI data for steel bar — World Steel Association (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.