Stainless Steel 17-4PH

17-4PH, also known as UNS S17400, is a precipitation hardening stainless steel. The "17-4" in its name means that it contains about 17% chromium and 4% nickel, and "PH" means precipitation hardening. This material is mainly used for high-strength, corrosion-resistant applications.

17-4PH is a common stainless steel material, also known as 630 stainless steel. It is a precipitation hardening stainless steel with excellent corrosion resistance, good mechanical properties and heat treatment plasticity.

Alloy 17-4PH Composition

17-4PH Physical Properties

Density:  0.280 Ibs/in3, 7.75 g/cm³

Specific Heat: 0.11 BTU/lb-°F @ 70°F, 460 J/kg-°C @ 20°C

Melting Range: 2560 – 2625°F, 1404 – 1440°C

17-4PH International Equivalent Grades

SAE	JIS	NF	DIN	UNS	GB	ASTM	ISO	KS	EN	ISC
17-4PH	SUS 630	Z6CNU17-04	1.4542	S17400	0Cr17Ni4Cu4Nb	630	X5CrNiCuNb 16-4	STS 630	X5CrNiCuNb 16-4	S51740

17-4PH Mechanical Properties

Alloy 17-4PH Standard

17-4PH stainless steel has many material standards, such as AMS 5604, ASTM A693, ASTM A564, etc. These standards specify the 17-4PH chemical composition, mechanical properties, heat treatment methods, etc. The following are the material standards for stainless steel 17-4PH tubes, plates, forgings, round bars, wires, and rings:

Product	Standard	Show
17-4PH Stainless Steel Tubes	AMS 5643
17-4PH Stainless Steel Forging	AMS 5643
17-4PH Stainless Steel Bars	AMS 5643
17-4PH Stainless Steel Wire	AMS 5643
17-4PH Stainless Steel Ring	AMS 5643
17-4PH Stainless Steel Plates/Sheets/Strips	AMS 5604

Corrosion Resistance

The corrosion resistance of Alloy 17-4PH is comparable to 304 stainless steel in most environments, and is generally superior to the 400 series stainless steels. It is used in applications where the combination of moderate corrosion resistance and unusually high strength are required. Alloy 17-4PH has corrosion resistance comparable to 304L in some chemical, dairy, food, paper and petroleum applications. 

Alloy 17-4PH in the solution-annealed condition (Condition A) should not generally be put in service. The alloy is subject to brittle fractures and more sensitive to chloride stress corrosion cracking than the aged material. If risks of chloride stress corrosion cracking are present the higher aging temperatures should be selected over 1022°F (550°C), preferably 1094°F(590°C). 1022°F (550°C) is the recommended tempering temperature in chloride service. 1094°F (590°C) is preferred in H2S media. Alloy 17-4PH is subject to crevice corrosion and pitting attack when exposed to stagnant seawater for a duration of time.

Hot Forming

Heat uniformly at 1742 – 2192°F (950 – 1200°C). A full solution anneal, cooling lower than 76°F (25°C) and aging at the required temperature must occur after hot forming. The post forming heat treatment should be a function of the desired mechanical properties.

Cold Forming

Alloy 17-4PH has limited cold forming properties. Cold forming can only be undertaken on plates in the fully annealed condition. Stress corrosion resistance is enhanced by re-aging at the precipitation hardening temperature after cold working.

Cutting

Thermal cutting operations such as plasma cutting should be avoided. Mechanical cutting operations such as bandsaw, abrasive waterjet, shearing and machining are preferred.

Welding

Alloy 17-4PH can be readily welded by most standard processes including SMAW, GTAW, PAW and GMAW.

Machining

Alloy 17-4PH can be machined in both the solution treated and precipitation hardened conditions.  Machining characteristics may vary according to the hardness of the metal. High speed tools are acceptable, but carbide tools are preferred. Standard lubrication should be used. Dimensional changes as a result heat treatment  should be taken into account if very stringent tolerances are required.

Features

High tensile strength and hardness to 600°F

Corrosion resistant

Excellent oxidation resistance to about 1100°F

Creep-rupture strength to 900°F

Stainless Steel 17-4PH Applications

• Aerospace  —  structural  and  parts.

• Biomedical  —  hand  tools.

• Chemical Processing.

• Food Process Equipment.

• Mechanical Components.

• Nuclear Waste Processing and Storage.

• Oil  and  Gas  Production  —  foils, helicopter deck platforms, etc.

• Pulp  and  Paper  —  paper  mill equipment.

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