17-4PH
1.4542 / 630 · EN 10088 / ASTM A564 · 1.4542
17-4PH (1.4542 / 630) is a stainless steel (Precipitation Hardening family) to EN 10088 / ASTM A564 (1.4542). It has a specified 0.2 % proof stress of 1000 MPa and a typical tensile strength of about 1070 MPa, with a uniform elongation of 10 %. Nominal carbon content is around 0.07 %. For nonlinear FEA, a bilinear model uses E = 200 GPa up to yield and a tangent modulus of 751 MPa above it. Unusually for a stainless steel it can be hardened by heat treatment, trading some corrosion resistance for strength and wear resistance.
Bilinear material model — nonlinear FEA
Uniform elongation εu = 10.0% · conservative analysis limit ½εu = 5.0%
Bilinear (BISO) approximation. Elastic modulus E up to the 0.2% proof stress R_p0.2, then a single tangent slope Eₜ to the ultimate tensile strength: Eₜ = (Rₘ − R_p0.2) / (εu − R_p0.2/E − 0.002), where εu is the uniform elongation and Rₘ is a typical (nominal) UTS within the specified band. The half-εu figure is a conservative strain limit for the analysis. Treat these as guidance for first-pass models; for critical work use a measured true stress–strain curve for the actual product and condition.
Ratings — engineering judgement
Weldabilitypoor
Difficult — hardens on cooling. Preheat and post-weld tempering are normally required.
Machinabilitymoderate
Soft and gummy at low carbon — sharp tooling helps surface finish.
Corrosion resistancegood
Good atmospheric and mild-chemical resistance from the chromium content; less resistant than austenitics in chlorides.
Hardenabilitygood
Hardenable by heat treatment (unusual among stainless steels).
Toughnessmoderate
Adequate toughness for general use at ambient temperature.
Indicative ratings derived from composition and family — engineering guidance, not specification values.
Physical properties
| Density | 7750 | kg/m³ |
| Elastic modulus | 200 | GPa |
| Shear modulus | 76.9 | GPa |
| Poisson's ratio | 0.30 | |
| Thermal expansion | 10.5 | ×10⁻⁶/°C |
| Thermal conductivity | 25 | W/(m·K) |
| Specific heat | 460 | J/(kg·K) |
| Magnetic | Yes |
Typical values for precipitation hardening steel — use the mill certificate for the specific product.
Chemical composition (wt %)
Composition per EN 10088 / AISI for 17-4PH (1.4542).
Available forms
Common applications
- Process, food and pharmaceutical equipment
- Architectural and marine hardware
- Fasteners and fittings for corrosive service
- Tanks, pipework and heat exchangers
History
Precipitation-hardening stainless steels were developed for aerospace: they are supplied soft and machinable, then given a single low-temperature ageing treatment that precipitates copper- or aluminium-rich phases to reach very high strength with minimal distortion — all while keeping useful corrosion resistance. The workhorse PH grade (also 1.4542 / 630) — soft to machine, then aged to ~1100 MPa; pump shafts, valves, aerospace.
- 194617-4PH introduced for high-strength corrosion-resistant aerospace parts
- 1950Semi-austenitic 17-7PH developed for springs and structures
This profile is generated from the grade's core data and family. Composition is decoded from the designation where its naming system defines it; physical properties are family-typical and ratings are indicative. Confirm critical values against the governing standard or the mill certificate. Equivalents, historical designations and hand-written expert notes are added per grade over time.