17-4 PH Round Bar Specification, Sizes, Grades and Buying Guide
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Table of Contents
- What Is the 17-4 PH Round Bar Specification?
- 17-4 PH Round Bar Grade Identification
- ASTM Specification for 17-4 PH Round Bar
- 17-4 PH Round Bar Chemical Composition
- 17-4 PH Round Bar Mechanical Properties
- 17-4 PH Round Bar Heat-Treatment Conditions
- 17-4 PH Round Bar Sizes and Dimensions
- 17-4 PH Round Bar Finishes
- 17-4 PH Round Bar Testing and Documentation
- How to Prepare a 17-4 PH Round Bar Inquiry
- Common Buying Mistakes
- Frequently Asked Questions
- Conclusion
What Is the 17-4 PH Round Bar Specification?
The 17-4 PH Round Bar Specification is important when purchasing this precipitation-hardening stainless steel for engineering, manufacturing or industrial applications.
17-4 PH is not simply identified by the words “stainless steel round bar.”
Depending on the requirement, a proper purchase specification can include the grade, UNS designation, applicable standard, heat-treatment condition, diameter, length, surface finish, testing requirements and documentation.
17-4 PH is commonly known as UNS S17400 and Type 630.
The alloy is a precipitation-hardening stainless steel developed for applications requiring a combination of high strength and useful corrosion resistance. Technical data from ATI identify 17-4 PH as UNS S17400 and show that different heat treatments can produce a wide range of mechanical properties.
For buyers, understanding the specification before requesting a quotation can prevent one of the most common problems in specialty steel purchasing:
Receiving a technically different product from what the application actually requires.
17-4 PH Round Bar Grade Identification
One of the first things an engineer or purchaser should know is how 17-4 PH is identified across different systems.
Common designations include:
| Designation | Identification |
|---|---|
| 17-4 PH | Common commercial name |
| UNS S17400 | UNS designation |
| Type 630 | Stainless steel type |
| AISI 630 | Common grade designation |
| EN 1.4542 | European material number |
| X5CrNiCuNb16-4 | Common EN designation |
Not every designation should automatically be treated as interchangeable in every purchasing situation.
The applicable product standard still matters.
For example, the current ASTM A564/A564M specification covers hot-finished and cold-finished age-hardening stainless-steel bars and shapes and specifically includes Type 630.
Therefore, a professional inquiry should ideally state both the material grade and the required standard.
ASTM Specification for 17-4 PH Round Bar
For many industrial purchasing requirements, ASTM A564/A564M is an important specification to understand.
ASTM describes A564/A564M as the specification for hot-rolled and cold-finished age-hardening stainless-steel bars and shapes.
It covers products including:
- Rounds
- Squares
- Hexagons
- Bar shapes
- Angles
- Tees
- Channels
The specification also allows these products to be produced through processes such as hot rolling, extrusion or forging. Type 630 may be supplied in solution-annealed or age-hardened conditions under the standard.
For critical orders, buyers should therefore avoid writing only:
“17-4 PH Round Bar required.”
A better inquiry would identify the required standard, condition and dimensions.
For the latest applicable requirements, buyers should verify the current edition directly through the ASTM International standards database.
17-4 PH Round Bar Chemical Composition
The chemical composition is another important part of the specification.
17-4 PH is primarily a chromium-nickel-copper precipitation-hardening stainless steel with niobium added as part of its alloy design.
Typical composition ranges associated with UNS S17400 include:
| Element | Typical Range / Maximum |
|---|---|
| Carbon | ≤ 0.07% |
| Chromium | 15.5–17.5% |
| Nickel | 3.0–5.0% |
| Copper | 3.0–5.0% |
| Niobium + Tantalum | 0.15–0.45% |
| Manganese | ≤ 1.0% |
| Silicon | ≤ 1.0% |
| Phosphorus | ≤ 0.04% |
| Sulfur | ≤ 0.03% |
Exact limits depend on the governing specification.
Technical data published for UNS S17400 confirm chromium, nickel, copper and niobium as key alloying elements.
This chemistry allows the material to respond to precipitation-hardening treatment and develop substantially different strength levels.
17-4 PH Round Bar Mechanical Properties
One of the main reasons engineers select 17-4 PH is its ability to achieve high mechanical strength.
However, there is an important point that buyers sometimes overlook:
17-4 PH does not have one single mechanical-property value.
The final properties depend on the material condition and heat treatment.
For example, technical data for ATI 17-4 PH bar show tensile strength values spanning a broad range depending on condition.
A simplified comparison is:
| Condition | General Characteristic |
|---|---|
| Condition A | Solution annealed |
| H900 | Very high strength and hardness |
| H1025 | High strength with a different toughness balance |
| H1075 | Increased toughness compared with lower ageing conditions |
| H1150 | Higher toughness and ductility, lower strength than H900 |
These should not be treated as guaranteed specification values.
The actual mechanical requirements should always be taken from the applicable material standard, purchase order or customer specification.
17-4 PH Round Bar Heat-Treatment Conditions
Heat treatment is one of the defining features of 17-4 PH.
Unlike ordinary stainless steel grades where the material condition may remain relatively straightforward, 17-4 PH can be aged to obtain different mechanical properties.
Condition A
Condition A is the solution-annealed condition.
It is commonly used as the starting condition before precipitation hardening.
H900
H900 is associated with high strength and hardness.
Technical data from ATI indicate that ageing around 900°F (482°C) produces the highest strength range among the standard conditions listed in its material data.
H1025
H1025 provides a different balance of strength and toughness.
It can be selected when maximum strength is not the only design consideration.
H1075
H1075 moves further toward a combination of strength and toughness.
H1150
H1150 is generally associated with greater toughness and ductility compared with lower-temperature ageing conditions, while giving up some strength.
The correct condition therefore depends on the component.
A shaft carrying a heavy mechanical load may have different requirements from a component where toughness is more important.
17-4 PH Round Bar Sizes and Dimensions
There is no single universal diameter that defines a 17-4 PH Round Bar.
The available size depends on the supplier, mill, manufacturing route and stock position.
Depending on the requirement, round bars can be sourced in:
- Small diameters
- Medium diameters
- Large diameters
- Cut lengths
- Standard mill lengths
- Custom lengths
- Machining stock
A purchase inquiry should clearly state:
Diameter × Length × Quantity
For example:
17-4 PH Round Bar, 40 mm Dia × 3 metre length, required quantity 500 kg.
If the finished component is being machined, the buyer should also clarify whether the quoted diameter is the finished dimension or raw machining dimension.
This can prevent costly misunderstandings.
17-4 PH Round Bar Finishes
The required surface condition can be just as important as the material grade.
Depending on the application, buyers may request:
Hot Finished
Suitable for applications where a basic hot-finished surface is acceptable and further machining will be performed.
Cold Finished
Provides improved dimensional control and surface condition compared with standard hot-finished material.
Rough Turned
Useful where the bar will undergo additional machining.
Ground
Used where tighter dimensional control and improved surface finish are required.
Polished
Selected for applications where surface appearance or surface condition is important.
Machined
Can be supplied to customer-defined dimensions or machining requirements.
The final choice depends on the component design and manufacturing process.
17-4 PH Round Bar Testing and Documentation
For industrial purchasing, the material itself is only one part of the order.
Documentation can be equally important.
Depending on the application and customer specification, buyers may request:
- Chemical analysis
- Tensile test
- Yield strength
- Elongation
- Hardness testing
- Dimensional inspection
- PMI
- Ultrasonic testing
- Heat-treatment records
- Material Test Certificate
- Certificate of Conformance
- Traceability documentation
ASTM A564/A564M includes requirements for testing such as tension, impact and hardness testing for the products covered by the specification.
For critical applications, testing requirements should be confirmed before the order is placed, rather than after the material has been dispatched.
How to Prepare a 17-4 PH Round Bar Inquiry
A clear inquiry makes it much easier for a supplier to provide the correct quotation.
Instead of sending:
“Need 17-4 PH bar.”
Send something like:
Material: 17-4 PH / UNS S17400
Standard: ASTM A564/A564M, if applicable
Condition: H900 / H1025 / H1075 / H1150 / Condition A
Product: Round Bar
Diameter: 50 mm
Length: 3 metres
Quantity: 500 kg
Finish: Bright / Ground / Machined
Testing: As required
Documentation: MTC required
Application: Pump shaft
This gives the supplier substantially more information.
It also helps the buyer compare quotations on a like-for-like basis.
Common Buying Mistakes
Ordering Without a Heat-Treatment Condition
This is one of the biggest mistakes.
Two 17-4 PH bars can have substantially different mechanical properties depending on their condition.
Comparing Prices Without Comparing Specifications
A cheaper quotation may not represent the same:
- Grade
- Condition
- Size
- Finish
- Testing
- Documentation
- Origin
Always compare the complete technical specification.
Ignoring the Finished Component Size
If a customer needs a 45 mm finished shaft, ordering a 45 mm raw bar without considering machining allowance may not be appropriate.
The machining process should be considered before finalizing the bar size.
Not Specifying Testing Requirements
If PMI, ultrasonic testing, hardness testing or another inspection is required, it should be mentioned in the purchase inquiry.
Assuming 17-4 PH Is Always Supplied in H900
It isn’t.
The material can be supplied in different conditions depending on the specification and application.
Why 17-4 PH Round Bar Is Different From Ordinary Stainless Steel Bar
The biggest difference is not simply corrosion resistance.
It is the ability to obtain high strength through precipitation hardening.
ATI’s technical data show that UNS S17400 can achieve a broad range of tensile and yield strengths depending on the heat-treatment condition.
That makes 17-4 PH particularly interesting for applications where designers want a stainless steel with significantly higher mechanical strength than many conventional austenitic stainless steels.
However, higher strength does not automatically make it suitable for every environment.
Material selection still needs to consider:
- Corrosion exposure
- Temperature
- Mechanical loading
- Wear
- Fabrication
- Welding
- Machining
- Heat treatment
- Required standards
Frequently Asked Questions
What is the specification of 17-4 PH Round Bar?
17-4 PH Round Bar is commonly identified as UNS S17400 or Type 630. ASTM A564/A564M is an important specification covering age-hardening stainless-steel bars and shapes, including Type 630.
What is the equivalent of 17-4 PH?
Common designations include UNS S17400, Type 630, AISI 630 and EN 1.4542.
Is 17-4 PH a stainless steel?
Yes. It is a precipitation-hardening stainless steel.
What is the strongest 17-4 PH condition?
H900 is generally associated with the highest strength among the commonly referenced standard ageing conditions, although exact values depend on the applicable specification and product form.
Can 17-4 PH Round Bar be machined?
Yes. The material can be machined, and the selected material condition should be considered when planning machining operations.
Is 17-4 PH Round Bar available in different sizes?
Yes. Commercial availability depends on the supplier, manufacturing route and stock. Buyers should specify the required diameter, length and quantity.
What documents should I request with 17-4 PH Round Bar?
Depending on the application, buyers may request a Material Test Certificate, chemical analysis, mechanical test results, hardness results, dimensional inspection and other specified inspection documents.
Conclusion
Understanding the 17-4 PH Round Bar Specification is essential before purchasing the material for an industrial application.
The grade name alone does not provide the complete picture.
A proper specification should consider the material designation, applicable standard, heat-treatment condition, dimensions, finish, testing and documentation.
17-4 PH is available in conditions such as Condition A, H900, H1025, H1075 and H1150, with each condition providing a different balance of mechanical properties.
ASTM A564/A564M is an important standard for age-hardening stainless-steel bars and shapes, while technical material data can help engineers understand the effect of different conditions on properties.
For buyers, the best inquiry is therefore not simply:
“Give me your price for 17-4 PH Round Bar.”
A better inquiry specifies:
Grade + Standard + Condition + Diameter + Length + Quantity + Finish + Testing + Documentation.
This makes it easier to compare suppliers and ensures that the quoted material is aligned with the intended application.
If you are sourcing 17-4 PH Round Bar for a shaft, valve, pump, engineering component, aerospace requirement or other industrial application, Manan Steel & Metals can evaluate the requirement based on the dimensions and technical specification provided.
Suggested Images
Featured Image
Image: Industrial 17-4 PH stainless steel round bars arranged in a steel stockyard with a close-up of a machined round bar.
ALT: 17-4 PH Round Bar Specification
Image 2
Image: Technical infographic showing UNS S17400, Type 630 and EN 1.4542 designations.
ALT: 17-4 PH UNS S17400 Type 630 specification
Image 3
Image: Comparison chart showing Condition A, H900, H1025, H1075 and H1150.
ALT: 17-4 PH heat treatment conditions
Image 4
Image: Precision-machined 17-4 PH round bar components such as shafts, pins and valve stems.
ALT: 17-4 PH Round Bar industrial applications
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- 17-4 PH Round Bar
- Stainless Steel Round Bars
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Outbound Links Already Built Into This Article
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- ASTM A564/A564M — specification reference
- MatWeb ATI 17-4 PH Bar — technical properties
- MatWeb/ATI 17-4 PH condition data — heat-treatment information