MATERIALS · STAINLESS STEEL

17-4 PH Stainless Steel

AISI 630 (17-4 PH) / 1.4542. 17-4 PH (AISI 630) is a martensitic precipitation-hardening stainless steel with about 15–17.5% chromium, 3–5% nickel and 3–5% copper. Parts are usually machined in the solution-treated Condition A and then given a single low-temperature ageing treatment that raises tensile strength to as much as 1310 MPa minimum (H900) with little distortion. Its corrosion resistance is broadly comparable to 304 in most media.

DENSITY

7.75 g/cm³

HARDNESS

Cond. A: 363 HB

TENSILE STRENGTH

Cond. A: 1030–1100 typical MPa

MACHINABILITY

Fair (45%)

TURNING, CARBIDE

80–160 m/min

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17-4 PH STAINLESS STEEL

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EQUIVALENT GRADES

Same steel, other names.

Nearest equivalents across standards. Check the exact standard on critical parts.

StandardGrade
AISI/SAE630
UNSS17400
ASTMA564 Type 630 (bar), A693 (plate, sheet, strip)
EN / W.NrX5CrNiCuNb16-4 / 1.4542
ISX05Cr16Ni4CuNb (IS 6603:2024)
JISSUS630

Also known as: 17-4 PH, 17-4, 630, SS630, 1.4542, X5CrNiCuNb16-4, S17400, 17Cr-4Ni, SUS630

CHEMICAL COMPOSITION

What it is made of.

ElementWeight %
C≤0.07
Si≤1.00 (ASTM A564); ≤0.70 (EN 10088-3)
Mn≤1.00 (ASTM A564); ≤1.50 (EN 10088-3)
P≤0.040
S≤0.030
Cr15.0–17.5 (ASTM A564); 15.0–17.0 (EN 10088-3)
Ni3.0–5.0
Cu3.0–5.0
Nb (+Ta)0.15–0.45 (ASTM A564); 5×C–0.45 (EN 10088-3)
Mo≤0.60 (EN 10088-3 only)

MECHANICAL PROPERTIES

Strength and hardness.

ConditionBar: Condition A (solution treated) typical values; aged conditions are ASTM A564 / AMS 5643 minimums
Tensile strength (MPa)Cond. A: 1030–1100 typical (1200 max, EN 10088-3); H900: 1310 min; H1025: 1070 min; H1150: 930 min
Yield strength (MPa)Cond. A: 760–790 typical; H900: 1170 min; H1025: 1000 min; H1150: 725 min
Elongation (%)Cond. A: 5–8 typical; H900: 10 min; H1025: 12 min; H1150: 16 min
HardnessCond. A: 363 HB (38–39 HRC) max; H900: 40–47 HRC; H1025: 34–42 HRC; H1150: 28–37 HRC
Density (g/cm³)7.75

MACHINING

How to machine 17-4 PH Stainless Steel.

Turning, carbide (m/min)80–160
Turning, HSS (m/min)15–25
MachinabilityFair (Condition A), 45% (AISI B1112 = 100%, Condition A (published figures 40–45%; lower when aged to high strength))

Most 17-4 PH parts are machined in Condition A (solution treated, up to about 363 HB), where it cuts roughly like 304 but gives long, gummy chips, so chip-breaker geometry and a steady feed matter. Age after machining: the low-temperature treatment causes little distortion, only a small, predictable contraction (about 0.05% at H900) that close-tolerance work should allow for. If cutting after ageing, H1150 machines better than H900; for H900 drop carbide speeds to roughly 55–85 m/min and use TiAlN- or TiCN-coated tools. Use flood coolant throughout.

APPLICATIONS

Where it is used.

Valve and engine componentsGearsHigh-strength shafts, including boat shaftsTurbine bladesMoulding diesOilfield and chemical process componentsAerospace parts

INDUSTRIES THAT USE IT

Aerospace and Defence ComponentsMedical Device Components

PROCESSING

Heat treatment and welding.

Heat treatmentSolution treat (Condition A) at about 1025–1055 °C and cool to below 32 °C, then age and air cool: H900 is 1 h at 482 °C, H1025 is 4 h at 552 °C and H1150 is 4 h at 621 °C. Ageing at higher temperatures lowers strength but improves toughness and resistance to stress corrosion cracking.
WeldingReadily welded by common fusion and resistance methods, usually without preheat; use matching AWS E/ER630 filler and age (or solution treat and age) after welding to restore strength.
Supplied asRound bar, Hex bar, Plate, Sheet, Strip, Forgings

QUESTIONS

About 17-4 PH Stainless Steel.

What do H900, H1025 and H1150 mean?

They are ageing conditions named after the ageing temperature in °F: H900 is 1 hour at 482 °C, while H1025 and H1150 are 4 hours at 552 °C and 621 °C. H900 gives the highest strength (1310 MPa minimum tensile for bar); higher ageing temperatures give lower strength but better toughness and resistance to stress corrosion cracking.

Is 17-4 PH magnetic?

Yes. Unlike 304 and 316, 17-4 PH has a martensitic structure and is strongly magnetic in all conditions, including the solution-treated Condition A.

Should 17-4 PH be machined before or after ageing?

Most parts are machined in Condition A and then aged, because ageing is a low-temperature treatment with little distortion; allow for a small contraction of about 0.05% at H900. Machining after ageing is possible but slower and harder on tools, with H1150 easier than H900. Condition A material should not normally be put into service without ageing.

RELATED MATERIALS

Compare with similar grades.

STAINLESS STEEL

SS303 Stainless Steel

AISI 303 / 1.4305 · 8 g/cm³

STAINLESS STEEL

SS304 Stainless Steel

AISI 304 / 1.4301 · 8 g/cm³

STAINLESS STEEL

SS316 / 316L Stainless Steel

AISI 316 / 316L / 1.4401 / 1.4404 · 8 g/cm³

STAINLESS STEEL

SS410 Stainless Steel

AISI 410 / 1.4006 · 7.75 g/cm³

Data reviewed 2026-10-02 against:

Typical values for reference. Always check the mill certificate and the standard your customer specifies.

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