Selection summary
Overview
15-5 PH is a chromium-nickel-copper precipitation-hardening stainless steel developed for high strength, hardness, good forgeability, and improved transverse toughness compared with conventional 17-4 PH processing. Properties depend on solution treatment, aging condition, product form, section size, and orientation, so the condition must be part of every drawing, certificate, and acceptance test.
This page separates standard-oriented limits from typical reference data. Purchase acceptance comes from the ordered specification and certified material test report.
Names and systems
Identity & standards
Similar designations across ASTM, EN, JIS, and other systems are not automatically interchangeable. Product form and ordered standard control chemistry, properties, dimensions, condition, and testing.
Reference chemistry
Composition
| Element | Reference range | Why it matters |
|---|---|---|
| Chromium | 14.0–15.5% | Corrosion resistance |
| Nickel | 3.5–5.5% | Martensitic transformation and toughness |
| Copper | 2.5–4.5% | Precipitation hardening |
| Niobium + tantalum | 0.15–0.45% | Precipitation and microstructure control |
Concise grade-family reference only. Confirm every element limit against the current standard for the exact product ordered.
Condition matters
Reference properties
H900, H1025, H1075, H1150 and specification variants differ materially
Product form, section, orientation, and aging condition must be named
Typical room-temperature engineering reference
Environment first
Corrosion behavior
Provides useful corrosion resistance for many aerospace, industrial, and process components when correctly heat treated and finished.
It is not a universal substitute for 304/316 and condition, stress, chloride exposure, crevices, and surface contamination affect performance.
Temperature, concentration, deposits, crevices, stress, surface finish, cleaning, and fabrication quality can change service performance.
Service limits
Temperature & service
Long exposure near or above the aging range can alter strength and toughness; service temperature must be assessed against the ordered condition.
Delivery condition
Heat treatment & condition
15-5 PH is solution treated and then precipitation aged to an explicitly ordered condition such as H900, H1025, H1075, or H1150 under the applicable specification.
Aging condition changes strength, toughness, stress-corrosion margin, dimensions, and sometimes machinability; tests must use the ordered product orientation and section.
Process route
Fabrication
Machine in the solution-treated condition where practical, then age to the ordered condition with distortion and stock allowance controlled.
Welding and postweld aging require a qualified route that preserves required strength, toughness, and corrosion behavior.
Magnetic response: Magnetic in solution-treated and aged martensitic conditions.
Decision boundaries
Comparisons & substitution
15-5 PH is generally compared with 17-4 PH when greater transverse toughness and forgeability are desired, but the two UNS grades and specification requirements are not interchangeable.
More highly overaged conditions trade strength for toughness and stress-corrosion margin; 300-series stainless remains preferable when weldability or corrosion, rather than ultra-high strength, is primary.
Where it is used
Applications
Ordering scope
Product forms & standards
Bars, shapes, forgings, and machined stock under the applicable PH stainless product standard with both starting and final condition stated.
Plate, sheet, strip, or wire under the form-specific standard, including transformation, cold-work, aging, direction, and final-property requirements.
Decision support
Selection guidance
Choose this grade when
- High strength and transverse toughness are required in a precipitation-hardened forging or bar.
- A recognized product specification and qualified heat treater can certify the exact aging condition.
Review another grade when
- The design assumes a generic PH strength without specifying H condition, orientation, or section.
- Maximum corrosion resistance, extensive welding, or low magnetic response is the primary requirement.
Before ordering
Procurement checklist
Name the governing product specification and edition, exact UNS designation, dimensions, tolerances, finish, and delivery or heat-treatment condition.
Require a traceable material test report and verify chemistry, mechanical tests, heat treatment, marking, and any supplementary examination against the purchase order.
State the service environment, design temperature, fabrication route, inspection plan, certification, packaging, and any regulatory or end-user approval before order release.
Traceable evidence