Steel S50C · temper
Steel S50C Annealed
Properties of the Annealed condition, compared with the other S50C tempers.
Pick when maximum machinability, cold formability or easiest drilling is needed before hardening.
What is S50C Annealed?
S50C Annealed is S50C in the Annealed temper — pick when maximum machinability, cold formability or easiest drilling is needed before hardening. S50C Annealed has a yield strength of 365 MPa (52.9 ksi) and a tensile strength of 636 MPa (92.2 ksi) — weaker than 71% of steel grades. Elongation at break is 24% and the elastic modulus is 205 GPa (29.7 Msi). S50C Annealed has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). Normalized is the default condition FabDigit quotes; Annealed is available on request or by drawing note.
Advantages
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- High electrical conductivity — 10 % IACS, better than 82% of steel grades
Limitations
- Low fracture toughness — 50 MPa·√m (45.5 ksi·√in), worse than 87% of steel grades
S50C Annealed properties
Typical room-temperature values for S50C Annealed — 13 properties are specific to this condition; the rest are grade-level values shared by every S50C temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
S50C Annealed has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
S50C Annealed has a yield strength of 365 MPa (52.9 ksi) and a tensile strength of 636 MPa (92.2 ksi) — weaker than 71% of steel grades. Elongation at break is 24% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
S50C Annealed is rated for continuous service to 350°C (662 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
S50C Annealed conducts electricity at 10 % IACS, better than 82% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of S50C Annealed takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
S50C Annealed's machinability is good (55/100, better than 62% of steel grades); weldability fair (40/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other S50C tempers and conditions
S50C is also supplied in 8 other conditions. The full side-by-side table is on the S50C overview.
- NormalizedDefaultDefault stocked condition: uniform fine pearlitic structure, balanced strength and machinability for general shafting and mold plate.427 MPa yield · 217 HB
- Q&T 40-45 HRCMaximum through-hardness practical for S50C in small sections where wear resistance dominates over toughness.1,050 MPa yield · 43 HRC
- Q&T 34-38 HRCHigher-strength Q&T level for wear-loaded pins, cams and small shafts where impact demand is moderate.850 MPa yield · 36 HRC
- Q&T 28-32 HRCGeneral-purpose quench-and-temper level for shafts and gear blanks needing toughness with moderate strength.700 MPa yield · 30 HRC
- CDChoose for close-tolerance, bright bar used as-supplied for shafts, pins and studs with higher yield strength.580 MPa yield · 197 HB
- IH 52-58 HRCUse for shaft journals, guide rails and sprocket teeth needing a hard wear surface over a tough normalized core.430 MPa yield · 55 HRC
- PH 190-220HBStandard S50C mold-base plate condition: stress-relieved, machined flat, used directly without further heat treatment.420 MPa yield · 205 HB
- HRCheapest stock form for weld fabrications and parts that will be machined then heat treated.380 MPa yield · 197 HB
- AnnealedPick when maximum machinability, cold formability or easiest drilling is needed before hardening.365 MPa yield · 187 HB
Working with S50C Annealed
Is S50C easy to machine?
Machines predictably at ~50% of 1212; best in annealed or normalized state with carbide tooling, 120–200 m/min turning, ample coolant to avoid built-up edge.
Can S50C be welded?
CE ≈ 0.6 — preheat 200–300 °C, use low-hydrogen E7018/ER70S electrodes and post-weld stress relief or temper to avoid HAZ cracking.
Can S50C be formed, bent or molded?
Hot forge 1100–1200 °C with slow cooling; cold bending is limited — use generous radii (≥3t) in the annealed condition only.
What surface finishes work on S50C?
No corrosion resistance bare — protect with black oxide, phosphate, zinc/hard-chrome plating, nitriding or paint; polishes to a fair mold-plate finish but carbide inclusions limit mirror work.
S50C 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 |
|---|---|---|
| CJIS G4051 | 0.47 – 0.53 | 0.5 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Curesidual, max | ≤ 0.3 | 0.1 |
| Niresidual, max | ≤ 0.2 | 0.05 |
| Crresidual; Ni+Cr ≤ 0.35 | ≤ 0.2 | 0.05 |
| Fe | balance | — |
S50C Annealed — frequently asked
What is S50C Annealed used for?
S50C Annealed is typically used for crankshafts, shafts and industrial bolts. In short: workhorse Japanese carbon bar.
What is the yield strength of S50C Annealed?
S50C Annealed has a typical yield strength of 365 MPa (52.9 ksi) and a tensile strength of 636 MPa (92.2 ksi) — weaker than 71% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is S50C Annealed easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines predictably at ~50% of 1212; best in annealed or normalized state with carbide tooling, 120–200 m/min turning, ample coolant to avoid built-up edge.
Can S50C Annealed be welded?
With care — weldability is rated fair (40/100). CE ≈ 0.6 — preheat 200–300 °C, use low-hydrogen E7018/ER70S electrodes and post-weld stress relief or temper to avoid HAZ cracking.
What surface finishes work on S50C Annealed?
No corrosion resistance bare — protect with black oxide, phosphate, zinc/hard-chrome plating, nitriding or paint; polishes to a fair mold-plate finish but carbide inclusions limit mirror work.
Can S50C Annealed be formed, bent or molded?
Hot forge 1100–1200 °C with slow cooling; cold bending is limited — use generous radii (≥3t) in the annealed condition only.
What is the maximum service temperature of S50C Annealed?
S50C Annealed is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S50C Normalized and S50C-CD?
Normalized is the default condition — default stocked condition: uniform fine pearlitic structure, balanced strength and machinability for general shafting and mold plate. CD: choose for close-tolerance, bright bar used as-supplied for shafts, pins and studs with higher yield strength. Yield strength is 427 MPa in Normalized versus 580 MPa in CD.
Can FabDigit make parts in S50C Annealed?
Yes — S50C Annealed 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 — JSA (2016)
- GB/T 699 — Quality carbon structural steels (50 ) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels (AISI 1050) — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- ASTM A29/A29M — Steel bars, carbon and alloy, hot-wrought — ASTM (2020)
- Mold base plate (S50C) product data — LKM / FUTABA mold base catalogs (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.