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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.
Grade | C≤ | Si≤ | Mn≤ | P≤ | S≤ | Cr | Ni | Cu | Nb+Ta |
17-4PH | 0.07 | 1 | 1 | 0.04 | 0.03 | 15-17.5 | 3-5 | 3-5 | 0.15-0.45 |
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
| 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 |
Grade | Tensile, min，ksi[MPa] | Yield, 0.02%offset, min, ksi[MPa] | Elongation, %(min) | Hardness |
17-4PH | 23.3[160] | 16.68[115] | 5 | 217HBW |
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
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.
