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Home Stainless Steel AISI631-1.4568-17-7PH-UNS S17700-X7CrNiAl17-7-SUS631

AISI631-1.4568-17-7PH-UNS S17700-X7CrNiAl17-7-SUS631

631 (17-7PH, UNS S17700) is a typical precipitation-hardening stainless steel that combines high strength, good spring properties, and excellent corrosion resistance. Through solution treatment and age-hardening processes, the material can achieve a balanced combination of strength and toughness under different heat treatment conditions.
It is particularly suitable for applications requiring high strength, fatigue resistance, and dimensional stability.

DIN EN 10088-1：
Stainless steels - Part 1: List of stainless steels
AMS A693：
Standard Specification for Precipitation-Hardening Stainless and Heat-Resisting Steel Plate, Sheet, and Strip
ASTM F899：
Standard Specification for Wrought Stainless Steels for Surgical Instruments
ASTM A564：
Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes

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Chemical Composition

Element	C	Mn	P	S	Si	Cr	Ni	Al	Fe
Content (%)	≤0.09	≤1.00	≤0.04	≤0.03	≤1.00	16.00-18.00	6.50-7.75	0.75-1.50	balance

Heat Treatment Conditions and Mechanical Properties

Solution Treatment

Condition	Heating Temperature	Holding Time（h）	Tensile Strength (MPa)	Yield Strength (MPa)	Elongation（4D）	Reduction of Area（%）	Hardness ((HRB)
Solution Annealed	1900 ± 25 °F/1040±15℃	1	/	/	/	/	≤98

Aging Treatment

Condition	Heating Temperature	Holding Time（h）	Tensile Strength (MPa)	Yield Strength (MPa)	Elongation（4D）	Reduction of Area（%）	Hardness (HRC)
	1750 ℉/955 ℃	/	/	/	/	/	/
Aged	950℉/510℃	1h	≥1280	≥1030	6	10	≥41
	1400 ℉/760 ℃	/	/	/	/	/	/
Aged	1050℉/565℃	90min	≥1170	≥965	6	25	≥38

Supply Forms

Available Form	Size Range	Surface Finish	Length (Customizable)	Tolerance (Customizable)	Delivery Condition
Plate	T0.5-T200.0mm	Milled	L:200/250/300 W:200/300/500/1000	-0.0/+1.0	Solution Annealed
Bar	φ1.0-φ200.0mm	Ground / Precision Ground	3M/PCS	h6-h9	Solution Annealed
Wire	φ1.0-φ3.0mm	Ground / Precision Ground	1M/PCS	h6-h9	Solution Annealed
Tube	OD：1.0-10.0mm ID:0.08mm-2.0mm	Ground / Precision Ground	3M/PCS	h6-h9	Solution Annealed

Datasheet

Additional Info

A Brief History of 17‑4 PH Stainless Steel

17‑4 PH Stainless Steel—also known as Alloy 17‑4, UNS S17400, or Type 630—is a precipitation‑hardening martensitic stainless steel developed to deliver an exceptional combination of high strength, corrosion resistance, and fabricability. Introduced in the mid‑20th century, 17‑4 PH was engineered to bridge the performance gap between conventional stainless steels and high‑strength alloy steels.

By utilizing a copper‑based precipitation‑hardening mechanism, 17‑4 PH achieves significantly higher strength than austenitic grades while retaining useful corrosion resistance and dimensional stability—making it one of the most versatile stainless steels used in modern engineering applications.

How 17‑4 PH Was Developed

17‑4 PH was designed to solve a growing industrial challenge: the need for a stainless steel that could be easily machined and formed in the solution‑annealed condition, then strengthened through a simple heat‑treatment process without distortion. Metallurgists achieved this by balancing approximately 17% chromium and 4% nickel with copper and niobium additions, allowing for controlled precipitation during aging.

After solution annealing (Condition A), 17‑4 PH can be heat treated to a wide range of strength levels—most commonly H900, H1025, and H1150—by aging at specific temperatures. This heat‑treat response allows manufacturers to tailor tensile strength, hardness, and toughness to meet precise application requirements without sacrificing corrosion resistance.

Early Applications of 17‑4PH

As aerospace, defense, and industrial sectors demanded stronger materials that were also corrosion resistant, 17‑4 PH quickly gained widespread adoption. Its ability to achieve strength levels comparable to alloy steels—while maintaining stainless steel corrosion performance—made it ideal for early aircraft components, fasteners, valve parts, and structural hardware.

The alloy’s predictable heat‑treat behavior and excellent dimensional stability made it especially valuable in applications requiring tight tolerances and repeatable mechanical properties, accelerating its use in bar products for precision‑machined components.

How 17‑4 PH Is Used Today

Today, 17‑4 PH Stainless Steel remains one of the most widely specified precipitation‑hardening stainless alloys. Available in regular bar, heat‑treated bar, and precision ground bar, it is used across industries where strength, corrosion resistance, and machinability must coexist.

Common applications include:

Aerospace: Structural fittings, landing gear components, shafts, fasteners

Oil & Gas: Valve components, pump shafts, downhole tools

Industrial manufacturing: Gears, pins, tooling components, wear‑resistant parts

Medical & food processing: Corrosion‑resistant high‑strength mechanical components

Heat‑treated bar provides enhanced tensile strength and hardness for load‑bearing or wear‑critical applications, while precision ground bar offers tight dimensional tolerances and superior surface finish—ideal for high‑accuracy machining and reduced secondary processing.

17‑4 PH maintains excellent mechanical properties up to approximately 600°F (315°C), delivering long‑term reliability in demanding environments while outperforming many traditional stainless and carbon steels.

Your Trusted Supplier for 17‑4 PH Stainless Steel

United Performance Metals is a global specialty metals solutions provider offering 17‑4 PH stainless steel in coil, sheet, plate, and bar, including solution‑annealed bar, heat‑treated bar, and precision ground bar. With advanced FIRSTCUT+® processing services and deep expertise supporting aerospace, oil & gas, medical, and industrial manufacturing customers, UPM delivers 17‑4 PH products cut and finished to your exact specifications.

Our reliable supply chain solutions and technical material support ensure consistent quality, performance, and on‑time delivery for your most demanding applications.

Contact United Performance Metals today to learn how 17‑4 PH stainless steel bar can enhance the strength, precision, and reliability of your next design.

FAQs

Typical Applications

Medical

Medical spring clips / Springs / Clips / Guidewire auxiliary components / Instrument return springs

Aerospace

Aerospace springs / Washers / Diaphragms / Retaining rings / Fixtures / Lightweight elastic structural components

Industrial

Wave springs / Disc springs / Elastic washers / Sensor spring contacts / Relay spring contacts

Robotics

Flexible spring clips / Spring contacts / Return springs / Compliant mechanisms / Micro gripper elastic components

Quality Services

ERP system management, full process traceability, and good batch stability.

Furnace numbering management ensures good material consistency.

Supports third-party testing and provides reports.

Chemical composition analysis (spectrometer analysis/oxygen, nitrogen, and hydrogen analyzer)

Mechanical properties (electronic tensile testing machine/Rockwell & Vickers hardness tester/impact testing machine)

Flaw detection (UT flaw detection)

Tissue examination (metallurgical microscope/electron microscope)

Heat treatment verification

Manufacturing services

Sheets/Pipes/Bars/Wires

Tolerances customized (H6-H9 grade)

Sheets/Pipes/Bars/Wires

Length and width customized (0.1M-3M or slit/cut to order)

CNC Pre-Machining

chamfering/face treatment/grinding/turning/milling

Sheets/Pipes/Bars/Wires

Custom sizes available (any non-standard dimensions can be customized)

Dimensional and Precision Control

straightness/roundness/coaxiality/dimensional tolerance records

Customized Heat Treatment

providing heat treatment based on material properties to achieve the desired delivery condition

Surface Control

roughness/fine grinding/film application on substrate

Marking and Coding Services

laser marking/inkjet coding

Shipping Packaging

Custom Size/Separate Boxes/Long-Distance Transportation

Engineering and Technical Support Services

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Support for medical industry applications

Supports OEM/OEM drawing processing

Material selection and alternative solutions

Tool Selection

Customized heat treatment solutions

Cost optimization

Industry-supporting resource consulting

Business & Supply Chain Services

Free samples, rapid verification

Comprehensive Product Range:We offer a wide range of products and can quickly provide samples that meet your requirements. Free trials are also available depending on your needs.

Supports small batch production and flexible MOQ

Our comprehensive product range is in stock, which can support small-batch sampling and increase flexibility.

24-Hour Quotation Response

An excellent sales and technical support team is available to provide you with dedicated service 24 hours a day.

Stable Supply Chain Production System

Stable raw material sources ensure batch consistency control. Safety stock is maintained, and production is managed according to ISO 13485 and ISO 9001 standards.