Steel S20C · supply condition · default condition
Steel S20C-CD
Properties of the CD condition, compared with the other S20C tempers.
Default stocked form: higher strength, tight tolerance and good surface for shafts, pins and turned parts.
What is S20C-CD?
S20C-CD is S20C supplied in the CD condition — default stocked form: higher strength, tight tolerance and good surface for shafts, pins and turned parts. S20C-CD 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). S20C-CD has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 89% of steel grades. It melts at 1,490°C (2,714 °F).
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-CD properties
Typical room-temperature values for S20C-CD — 14 properties are specific to this condition; the rest are grade-level values shared by every S20C temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
S20C-CD has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 89% of steel grades. It melts at 1,490°C (2,714 °F).
Mechanical16
S20C-CD 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-CD 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-CD conducts electricity at 10.8 % IACS, better than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 87% of steel grades.
Sustainability4
Producing a kilogram of S20C-CD 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-CD'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.
Other S20C tempers and conditions
S20C is also supplied in 6 other conditions. The full side-by-side table is on the S20C overview.
- CDDefaultDefault stocked form: higher strength, tight tolerance and good surface for shafts, pins and turned parts.400 MPa yield · 143 HB
- QTOnly worth it on small sections — low carbon limits hardenability, giving modest strength gains over normalizing.420 MPa yield · 170 HB
- CARBChoose for wear surfaces (gears, pins, bushings): hard 0.5–1.2 mm case on a tough, low-strength core.400 MPa yield · 60 HRC
- CD-SRUse when machined parts must stay straight — residual stress removed at ~550–650 °C with only small strength loss.350 MPa yield · 137 HB
- NUniform fine grain and predictable properties — the condition JIS specifies minimum strengths against (≥402 MPa UTS).280 MPa yield · 131 HB
- HRCheapest form for welded structures and parts to be fully machined or later heat treated.260 MPa yield · 121 HB
- ASoftest, most ductile state — pick for deep drawing, severe cold bending or before carburizing.240 MPa yield · 111 HB
Working with S20C-CD
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.
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.
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 | — |
S20C-CD — frequently asked
What is S20C-CD used for?
S20C-CD is typically used for general fabrication, brackets and welded plate. In short: cold-drawn machining bar.
What is the yield strength of S20C-CD?
S20C-CD 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-CD 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-CD 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-CD?
Not anodizable — protect by zinc plating, black oxide, phosphate + oil, nitrocarburizing or paint; carburize and grind where wear resistance is needed.
Can S20C-CD 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-CD?
S20C-CD 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.
Can FabDigit make parts in S20C-CD?
Yes — S20C-CD is available for CNC machining and sheet metal with instant online pricing. 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.