Steel P5
AISI/SAE P5 · UNS T51605
P5 (T51605) is a carburizing Cr-Ni mold steel with higher chromium than P2 or P3, producing a harder case for better wear resistance.
Reference datasheet — P5 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 Annealed condition
P5 tempers and conditions
P5 is supplied in 4 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft, as-supplied condition for machining and cold hubbing | Standard stock condition: maximum softness (105–116 HB) for cavity hubbing, machining and engraving before carburizing. | 290 | 490 | 30 | 110 HB | — |
900–925 °C air cool, grain refinement before final machining | Used after heavy forging or hubbing to refine grain and homogenize structure before the sub-critical anneal. | 340 | 560 | 26 | 150 HB | 35 W/m·K |
case 58–64 HRC | Final service condition: pack/gas carburize 900–925 °C, quench from ~790–830 °C, temper 175–260 °C for a hard wear-resistant case over a tough low-carbon core. | 750 | 1,000 | 12 | 62 HRC | — |
Carburized, hardened and hard-chrome plated cavity | Choose when molding corrosive resins (PVC, FR grades) or when extra cavity wear life and release are needed. | 760 | 950 | 14 | 66 HRC | 7.5 % IACS |
What is P5?
P5 (T51605) is a carburizing Cr-Ni mold steel with higher chromium than P2 or P3, producing a harder case for better wear resistance. It is supplied annealed, normalized or carburized and hardened (optionally chrome plated), and is the easiest grade in this group to hob and engrave — machinability 72 (about 70% of AISI 1212) and formability 80, with annealed values near 290 MPa yield, 490 MPa tensile, 30% elongation and 110 HB. Service temperature is limited to 350 °C and corrosion resistance is low (score 15), so cavities must be plated or oiled. P20 replaces it where pre-hardened plate is acceptable. P5 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). P5 has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 88% of steel grades. Elongation at break is 30% and the elastic modulus is 205 GPa (29.7 Msi).
What is P5 used for?
- carburized mold inserts
- die components requiring hard cases
- small precision molds
Advantages
- Easy to machine — 72/100, better than 97% of steel grades
- Ductile — tolerates forming and impact — 30%, better than 93% of steel grades
- Forms and bends easily — 80/100, better than 93% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Low strength — 290 MPa (42.1 ksi), worse than 88% of steel grades
P5 properties
Typical room-temperature values for P5-Annealed; bars are the position among steel grades.
Physical3
P5 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).
Mechanical15
P5 has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 88% of steel grades. Elongation at break is 30% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
P5 is rated for continuous service to 350°C (662 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 12.4 µm/m·K (6.89 µin/in·°F).
Electrical3
P5 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of P5 takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 40%.
Manufacturability5
P5's machinability is very good (72/100, better than 97% of steel grades); weldability good (60/100); formability very good (80/100).
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. P5 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with P5
Is P5 easy to machine?
Very easy to machine and engrave in the annealed state (~70% of AISI 1212), but the soft low-carbon matrix tends to smear — use sharp positive-rake tools and finish before carburizing; after case hardening only grinding/EDM apply.
Can P5 be welded?
Low carbon makes repair welding practical with matching low-alloy or Ni-based filler; preheat 200–300 °C, and re-carburize or at least re-temper the repaired area.
Can P5 be formed, bent or molded?
Designed for cold hubbing (hobbing) of cavities — the master hub is pressed into the annealed blank, with stress-relief anneals between passes; hot forge 1050–1150 °C, finish above 900 °C.
P5 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 carburizing / cold hubbing | ≤ 0.1 | 0.1 |
| Mn | 0.2 – 0.6 | 0.4 |
| Si | 0.1 – 0.4 | 0.25 |
| Crgives the harder, more wear-resistant case vs P2/P3 | 2 – 2.5 | 2.25 |
| Nioptional residual/addition | ≤ 0.35 | 0.2 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on P5?
Carburized case takes a high polish and texture well; hard chrome or electroless nickel plating is common for corrosive resins and added wear life; keep oiled or plated as the alloy rusts freely.
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 P5 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T51605
How much does P5 cost?
P5 is a premium-cost steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
P5 — frequently asked
What is P5 used for?
P5 is typically used for carburized mold inserts, die components requiring hard cases and small precision molds. In short: easiest P-series to hob; higher-chromium case; best formability in family.
What is the yield strength of P5?
P5 has a typical yield strength of 290 MPa (42.1 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 88% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is P5 easy to machine?
Yes — machinability is rated very good (72/100, better than 97% of steel grades). Very easy to machine and engrave in the annealed state (~70% of AISI 1212), but the soft low-carbon matrix tends to smear — use sharp positive-rake tools and finish before carburizing; after case hardening only grinding/EDM apply.
Can P5 be welded?
Yes — weldability is rated good (60/100). Low carbon makes repair welding practical with matching low-alloy or Ni-based filler; preheat 200–300 °C, and re-carburize or at least re-temper the repaired area.
What surface finishes work on P5?
Carburized case takes a high polish and texture well; hard chrome or electroless nickel plating is common for corrosive resins and added wear life; keep oiled or plated as the alloy rusts freely.
Can P5 be formed, bent or molded?
Designed for cold hubbing (hobbing) of cavities — the master hub is pressed into the annealed blank, with stress-relief anneals between passes; hot forge 1050–1150 °C, finish above 900 °C.
What is the maximum service temperature of P5?
P5 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does P5 cost?
P5 is a premium-cost steel ($$$), cheaper than about 51% 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 — Standard Specification for Tool Steels Alloy — ASTM International (2022)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Tool Steels: P-type mold steels) — ASM International (1990)
- ASM Handbook Vol. 4: Heat Treating — Heat Treating of Tool Steels — ASM International (1991)
- Tool Steels, 5th Edition (Roberts, Krauss, Kennedy) — ASM International (1998)
- UNS T51605 alloy data — 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.