Grade 17-4PH
Precipitation hardening stainless · AISI 630 / SAE J467, UNS S17400, EN 1.4542
17-4 PH Precipitation-Hardening Stainless Steel (Grade 630), precipitation-hardening stainless steel.
Data sheet
| Designations | AISI 630 / SAE J467 · UNS S17400 · EN 1.4542 (X5CrNiCuNb16-4) |
|---|---|
| Standards | ASTM A564, ASTM A693, AMS 5643 |
Metallurgy
Reference data for 17-4 PH Precipitation-Hardening Stainless Steel (Grade 630), against ASTM A564, ASTM A693, AMS 5643.
Elemental composition
X5CrNiCuNb16-4 to 1.4542
- Chromium 16,25%15,00–17,50%
- Nickel 4,00%3,00–5,00%
- Carbon 0,040%max 0,070%
- Other additions 5,33%Cu, Nb+Ta, Mn, Si, P, S
- Iron 74,38%Balance
Proportions use the normalised midpoint of each specified range. The midpoint is a derived figure, not something the standard states: read the table for what is actually specified.
Performance profile
Comparative scores out of ten, for weighing one grade against another
These are relative ratings, not measured properties, and they carry no units. Use them to narrow a shortlist, then work from the specified values.
Composition as specified
| Element | Specified | Nominal |
|---|---|---|
| Iron Fe | Balance | 74,38% |
| Carbon C | max 0,070%cap | 0,040% |
| Chromium Cr | 15,00–17,50% | 16,25% |
| Nickel Ni | 3,00–5,00% | 4,00% |
| Copper Cu | 3,00–5,00% | 4,00% |
| Niobium+Tantalum Nb+Ta | 0,15–0,45% | 0,30% |
| Manganese Mn | max 1,00%cap | 0,50% |
| Silicon Si | max 1,00%cap | 0,50% |
| Phosphorus P | max 0,040%cap | 0,020% |
| Sulphur S | max 0,030%cap | 0,015% |
A cap is a ceiling, not a quantity: a heat may contain far less. The nominal column is the midpoint of each range, used for the chart's proportions only.
Mechanical and physical properties
| Property | Value |
|---|---|
| Tensile strength, ultimate | 1 030 MPa149,4 ksi |
| Yield strength, 0,2% offset | 790 MPa114,6 ksi |
| Elongation at break | 15% |
| Hardness | 330 HBW / 108 HRB |
| Modulus of elasticity | 196 GPa28,5 Mpsi |
| Density | 7,78 g/cm³0,28 lb/in³ |
| Thermal conductivity | 17,8 W/(m·K)123,4 BTU·in/(hr·ft²·°F) |
| Thermal expansion | 10,8 µm/(m·K)6 µin/(in·°F) |
Test condition not yet confirmed. These figures are typical values for the grade; the condition a bar was supplied in changes them materially, so ask us for the mill certificate before designing to a number.
Pitting resistance
PREN 16,25
Cr + 3,3 Mo + 16 N, across the full specified composition
- Freshwater0–20
- Brackish20–32
- Seawater32–40
- Extreme offshoreover 40
A standard states its elements as ranges, so a grade has a window rather than a single score. The bar is that window; the tick is the midpoint.
Corrosion and fabrication
Chloride and marine service
Corrosion resistance comparable to Type 304 in most media; susceptible to crevice attack in stagnant seawater.
Acidic and chemical media
Good in dilute organic acids and petroleum refinery environments; superior to standard martensitic grades.
Sensitisation and thermal behaviour
Precipitation hardened via sub-microscopic copper-rich epsilon phase precipitates during aging (480°C–620°C / H900–H1150).
Welding
Good; weldable in Condition A using AWS ER630; post-weld solution treat and age (STA) yields uniform properties without distortion.
Machining and cold forming
Machinability index 48% relative to AISI 1212. Moderate in Condition A; easily machined in annealed condition, followed by simple low-temperature aging heat treatment.
Where it is used
- Aerospace structural fittings, landing gear components, and actuators
- Pump shafts, impellers, and valve stems for nuclear and chemical service
- Gas turbine compressor blades and aerospace engine mounts
- Paper mill equipment and marine drive shafts
Aerospace · Defense · Nuclear · Petrochemical · Marine
Performance scores in full
The same six scores the profile plots, as numbers.
| Property | 17-4PH |
|---|---|
| Corrosion resistance | 7.5 / 10 |
| Weldability | 7 / 10 |
| High-temperature resistance | 7.2 / 10 |
| Tensile strength | 9.5 / 10 |
| Cold formability | 4.5 / 10 |
| Machinability | 5 / 10 |
This page is guidance for selecting a grade, not a specification. Design to the governing standard and the mill certificate for the heat you are supplied.
The specifications and data on this site are provided for general information only. Verify any real-world project with a qualified metallurgist before relying on these figures. We take no responsibility for the use and application of this information.