17-4 PH (S17400)

What is 17-4 PH and its applications?

17-4 PH (UNS S17400), also known as Type 630, is a chromium-nickel-copper precipitation-hardening stainless steel. It is used where high strength and hardness are required together with moderate corrosion resistance.

Loaded mechanical components: Parts requiring a defined strength and hardness balance.
Valve and process equipment: Components selected against both load and corrosion requirements.
Precision assemblies: Hardware with condition-specific dimensional and mechanical acceptance.

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Engineering Application & Selection Guide

Copper-rich precipitation strengthens its martensitic structure during aging. Conditions such as H900 and H1150 provide different strength, toughness and environmental-cracking behavior; the condition must be specified explicitly.

17-4 PH hex bolts — For loaded structures, state the aging condition and required tensile, hardness and toughness acceptance.
17-4 PH stud bolts — For valve connections, review chloride and sour-service exposure against the exact condition.
17-4 PH socket head cap screws — For precision tooling, define the machining, threading and heat-treatment sequence and final dimensional inspection.

Use the 17-4 PH condition guide before choosing or replacing an aging condition. H1150 is not a universal corrosion approval, and H900 is not suitable simply because it offers higher strength. Check the applicable environmental and design restrictions.

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17-4 PH Composition

Composition limits · wt.%

ElementWeight %

Cr: 15–17.5%
Ni: 3–5%
Cu: 3–5%
Nb: 0.15–0.45%
C: ≤0.07%
Mn: ≤1.0%
P: ≤0.040%
S: ≤0.030%
Si: ≤1.0%

ASTM / ASME specifications by product form

Finished-product requirements

Specify the finished-fastener mechanical requirements, condition and inspection separately from the starting-stock specification.

17-4 PH hex bolt requirements ↗

Fasteners · dimensional references

Product	Reference
Hex bolts	ISO 4014 / ISO 4017 · ASME B18.2.1
Threaded studs	DIN 976-1 · ASME B18.31.2
Hex nuts	ISO 4032 · ASME B18.2.2
Socket head screws	ISO 4762 · ASME B18.3
Flat washers	ISO 7089 / ISO 7090 · ASME B18.21.1
Custom fasteners	Customer drawing

Raw-material specifications

Product form / scope	Reference
Bar, wire & shapes · Specify the heat-treatment condition.	ASTM A564
Sheet, plate & strip · Product-form-specific material reference.	ASTM A693

Dimensions do not define material or finished-part compliance. Specify the grade, condition and applicable requirements.

How to specify round bar, plate, wire and strip ↗

17-4 PH Mechanical Properties

Reference sample and condition

Data basis: Typical reference values
Condition: H900
Test temperature: Room temperature
Heat treatment: Solution treated, then aged at 482°C (900°F).
Gauge length: 2 in (50.8 mm)

Key properties	Value
Tensile strength	1340 MPa
0.2% yield strength	1240 MPa
Elongation	10%

ATI · 17-4 PH · 2016 bulletin · pages 1–2 and 4–5; H900 typical properties ↗

Procurement and application guide

Specify the material and final condition

State H900, H1150 or the required condition explicitly.

Material forms in the technical reference: Plate · Sheet · Strip · Bar · Wire · Shapes.

Define the finished-part acceptance

Include the material or bolting specification, required final condition, dimensions and quantity. State the service medium, temperature and loading where known. Agree the required tests, inspection coverage and acceptance criteria for the finished part.

Start with the information you have

Send a drawing or share the product form and dimensions. Identify any undecided requirements for review rather than copying a typical property value into the purchase order.

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Condition-specific data

Catalogue reference by heat treatment

ASTM A564 catalogue references; separate from the producer typical values above.

Condition / size	Tensile MPa	Yield MPa	A5 %	Reduction of area %	Hardness HRC
H900 · ≤75 mm	≥1310	≥1170	≥10	≥40	≥40
H900 · >75–200 mm	≥1310	≥1170	≥10	≥35	≥40
H1025 · ≤200 mm	≥1070	≥1000	≥12	≥45	≥35
H1100 · ≤200 mm	≥965	≥795	≥14	≥45	≥31
H1150 · ≤200 mm	≥930	≥725	≥16	≥50	≥28
H1150D	≥860	≥725	≥16	≥50	24–33