Steel P6
AISI/SAE P6 · UNS T51606
P6 is a low-carbon Ni-Cr carburizing mold steel from the AISI P (plastic mold) group, supplied annealed near 195 HB (415 MPa yield, 655 MPa tensile) so cavities can be machined or cold-hobbed before case hardening.
Reference datasheet — P6 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 ANN condition
P6 tempers and conditions
P6 is supplied in 5 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Pick when cavities are to be cold-hobbed with a master punch; softest achievable structure. | 350 | 585 | 25 | 165 HB | 6 % IACS |
ANNDefault Annealed | Standard stock condition for machining or cold hobbing of cavities before carburizing. | 415 | 655 | 20 | 195 HB | — |
Normalized | Used to refine grain and homogenize forged or hobbed blanks before carburizing. | 550 | 830 | 17 | 23 HRC | 5.5 % IACS |
Hardened & tempered | Direct oil quench without carburizing for tough holder/backing parts that need strength but not a wear surface. | 900 | 1,100 | 14 | 35 HRC | — |
Carburized, hardened & tempered | Standard service condition: hard wear-resistant case over a tough low-carbon core for impact-loaded mold parts. | 930 | 1,150 | 12 | 60 HRC | 32 W/m·K |
What is P6?
P6 is a low-carbon Ni-Cr carburizing mold steel from the AISI P (plastic mold) group, supplied annealed near 195 HB (415 MPa yield, 655 MPa tensile) so cavities can be machined or cold-hobbed before case hardening. It is chosen where a mold sees repeated impact: the carburized case reaches about 58 HRC while the low-carbon core stays tough at 20 % elongation. The steel is not corrosion resistant, needs plating for aggressive resins, and is limited to 300 °C service; prehardened P20 is simpler when impact is not the driving load. P6 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). P6 has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 56% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
What is P6 used for?
- carburized mold cores
- impact-resistant mold inserts
- die components
Advantages
- Easy to machine — 62/100, better than 89% of steel grades
- Forms and bends easily — 70/100, better than 86% of steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
P6 properties
Typical room-temperature values for P6-ANN; bars are the position among steel grades.
Physical3
P6 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
P6 has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 56% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
P6 is rated for continuous service to 300°C (572 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical2
P6 has an electrical resistivity of 3×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of P6 takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 45%.
Manufacturability8
P6's machinability is good (62/100, better than 89% of steel grades); weldability good (60/100); formability very good (70/100).
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. P6 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with P6
Is P6 easy to machine?
Machine fully in the annealed state with sharp, positive-rake carbide or HSS; the soft, gummy low-carbon Ni-Cr matrix smears, so use high feed, flood coolant and finish before carburizing.
Can P6 be welded?
Weld only annealed or normalized material with a low-carbon/low-alloy filler, preheat 200–300 °C, then re-anneal or re-carburize; welding a carburized case invites cracking.
Can P6 be formed, bent or molded?
Its main advantage is cold hobbing — cavity impressions can be pressed into the soft annealed blank, with stress-relief anneals between hobbing passes.
P6 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 |
|---|---|---|
| Clow carbon for cold hobbability | 0.05 – 0.15 | 0.1 |
| Mn | 0.35 – 0.7 | 0.5 |
| Si | 0.1 – 0.4 | 0.25 |
| Cr | 1 – 1.75 | 1.5 |
| Nicore toughness | 3.25 – 3.75 | 3.5 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on P6?
Case-hardened surfaces polish and texture well after tempering; add hard chrome or electroless nickel for corrosion protection since the steel rusts readily.
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
Equivalent designations
Standards and trade names that resolve to Steel P6 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T51606
How much does P6 cost?
P6 is a standard-cost steel ($$), cheaper than about 71% 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.
P6 — frequently asked
What is P6 used for?
P6 is typically used for carburized mold cores, impact-resistant mold inserts and die components. In short: hobbable mold steel; tough core, hard case; impact-duty P grade.
What is the yield strength of P6?
P6 has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 56% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is P6 easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machine fully in the annealed state with sharp, positive-rake carbide or HSS; the soft, gummy low-carbon Ni-Cr matrix smears, so use high feed, flood coolant and finish before carburizing.
Can P6 be welded?
Yes — weldability is rated good (60/100). Weld only annealed or normalized material with a low-carbon/low-alloy filler, preheat 200–300 °C, then re-anneal or re-carburize; welding a carburized case invites cracking.
What surface finishes work on P6?
Case-hardened surfaces polish and texture well after tempering; add hard chrome or electroless nickel for corrosion protection since the steel rusts readily.
Can P6 be formed, bent or molded?
Its main advantage is cold hobbing — cavity impressions can be pressed into the soft annealed blank, with stress-relief anneals between hobbing passes.
What is the maximum service temperature of P6?
P6 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 P6-ANN and P6 CARB-58?
ANN is the default condition — standard stock condition for machining or cold hobbing of cavities before carburizing. CARB-58: standard service condition: hard wear-resistant case over a tough low-carbon core for impact-loaded mold parts. Yield strength is 415 MPa in ANN versus 930 MPa in CARB-58.
How much does P6 cost?
P6 is a standard-cost steel ($$), cheaper than about 71% 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
- ASTM A681 — Alloy Tool Steels — ASTM International (2015)
- ASM Handbook Vol.1: Properties and Selection: Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- Tool Steels, 5th ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- UNS T51606 alloy record — SAE/ASTM Unified Numbering System (2017)
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.