Steel C45Pb · temper
Steel C45Pb-A
Properties of the A condition, compared with the other C45Pb tempers.
Choose when maximum machinability and low hardness are wanted before final hardening.
What is C45Pb-A?
C45Pb-A is C45Pb in the A temper — choose when maximum machinability and low hardness are wanted before final hardening. C45Pb-A has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 580 MPa (84.1 ksi) — weaker than 80% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi). C45Pb-A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). CD is the default condition FabDigit quotes; A is available on request or by drawing note.
Advantages
- Easy to machine — 72/100, better than 97% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High electrical conductivity — 10.7 % IACS, better than 91% of steel grades
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
Limitations
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
- Low strength — 320 MPa (46.4 ksi), worse than 80% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 77% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
C45Pb-A properties
Typical room-temperature values for C45Pb-A — 11 properties are specific to this condition; the rest are grade-level values shared by every C45Pb temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
C45Pb-A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
C45Pb-A has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 580 MPa (84.1 ksi) — weaker than 80% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
C45Pb-A is rated for continuous service to 300°C (572 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
C45Pb-A conducts electricity at 10.7 % IACS, better than 91% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 87% of steel grades.
Sustainability4
Producing a kilogram of C45Pb-A takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
C45Pb-A's machinability is very good (72/100, better than 97% of steel grades); weldability poor (25/100); 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 C45Pb tempers and conditions
C45Pb is also supplied in 7 other conditions. The full side-by-side table is on the C45Pb overview.
- CDDefaultStandard stock condition: close tolerance, bright surface, high strength — the usual feed for CNC/auto-lathe turned parts.540 MPa yield · 205 HB
- QT 28-32 HRCOrdered when a drawing calls out a hardness band for wear and thread strength on small-diameter bar.750 MPa yield · 30 HRC
- QTUse for loaded shafts, pins and threaded parts needing higher yield with usable toughness.550 MPa yield · 21 HRC
- IHSelect for journals and guide surfaces needing a hard, wear-resistant case over a tough core.550 MPa yield · 55 HRC
- SHPick for slender or asymmetrically machined parts where cold-drawing stresses would cause distortion.500 MPa yield · 200 HB
- NUniform fine-pearlitic structure; balanced strength and toughness for general machined parts.380 MPa yield · 195 HB
- HRCheapest mill condition for parts that will be fully machined or later heat treated.340 MPa yield · 185 HB
- AChoose when maximum machinability and low hardness are wanted before final hardening.320 MPa yield · 180 HB
Working with C45Pb-A
Is C45Pb easy to machine?
Excellent for a 0.45 %C steel — lead gives short chips, lower cutting force and good surface finish; run high speeds with carbide, use dry or oil mist and collect swarf as lead-bearing waste.
Can C45Pb be welded?
Poor: 0.45 %C plus lead promotes hot cracking and porosity; avoid welding, or preheat 200–300 °C, use low-hydrogen consumables and post-weld temper, and ventilate for lead fume.
Can C45Pb be formed, bent or molded?
Limited cold formability (bend radii ≥3t, elongation <12 % in CD); hot form at 850–1150 °C but avoid holding near 1100 °C+ where lead causes hot shortness.
What surface finishes work on C45Pb?
No anodizing; protect with oil, phosphate, black oxide, zinc or nickel plating — bake after plating to limit hydrogen embrittlement in hardened conditions; polishes to a fair finish.
C45Pb 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 | 0.42 – 0.5 | 0.45 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.5 – 0.8 | 0.65 |
| P≤0.035 for quality-steel grades | ≤ 0.05 | — |
| Soften 0.020–0.040 to aid chip breaking | ≤ 0.05 | 0.03 |
| Pbfree-cutting addition | 0.15 – 0.35 | 0.25 |
| CrCr+Mo+Ni ≤ 0.63 total | ≤ 0.4 | — |
| Ni | ≤ 0.4 | — |
| Mo | ≤ 0.1 | — |
| Fe | balance | — |
C45Pb-A — frequently asked
What is C45Pb-A used for?
C45Pb-A is typically used for shafts, bolts and spindles. In short: leaded medium-carbon machining bar.
What is the yield strength of C45Pb-A?
C45Pb-A has a typical yield strength of 320 MPa (46.4 ksi) and a tensile strength of 580 MPa (84.1 ksi) — weaker than 80% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is C45Pb-A easy to machine?
Yes — machinability is rated very good (72/100, better than 97% of steel grades). Excellent for a 0.45 %C steel — lead gives short chips, lower cutting force and good surface finish; run high speeds with carbide, use dry or oil mist and collect swarf as lead-bearing waste.
Can C45Pb-A be welded?
Not readily — weldability is rated poor (25/100). Poor: 0.45 %C plus lead promotes hot cracking and porosity; avoid welding, or preheat 200–300 °C, use low-hydrogen consumables and post-weld temper, and ventilate for lead fume.
What surface finishes work on C45Pb-A?
No anodizing; protect with oil, phosphate, black oxide, zinc or nickel plating — bake after plating to limit hydrogen embrittlement in hardened conditions; polishes to a fair finish.
Can C45Pb-A be formed, bent or molded?
Limited cold formability (bend radii ≥3t, elongation <12 % in CD); hot form at 850–1150 °C but avoid holding near 1100 °C+ where lead causes hot shortness.
What is the maximum service temperature of C45Pb-A?
C45Pb-A is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C45Pb-CD and C45Pb-A?
CD is the default condition — standard stock condition: close tolerance, bright surface, high strength — the usual feed for CNC/auto-lathe turned parts. A: choose when maximum machinability and low hardness are wanted before final hardening. Yield strength is 540 MPa in CD versus 320 MPa in A.
Can FabDigit make parts in C45Pb-A?
Yes — C45Pb-A is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10083-2 Steels for quenching and tempering — non-alloy quality steels — CEN (2006)
- EN 10277-3 Bright steel products — free-cutting steels — CEN (2018)
- EN 10027-2 / Werkstoff-Nummer 1.1201 designation system — CEN (2015)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels — ASM International (1990)
- Bright bar / free-cutting steel datasheets (C45, C45Pb) — European bright-bar producers (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.