ISO/TR 15608 Material Group 7.3: Precipitation-hardened stainless steels such as 17-4PH with
C ≤ 0,35 % and 10,5 % ≤ Cr ≤ 30 %;
Features of ISO/TR 15608 Material Group 7.3: Precipitation-hardened stainless steels
Precipitation hardening grades have higher alloying contents than martensitic steel grades. They contain nickel, and in order to achieve hardening by aging additions of copper, aluminium, titanium, niobium and molybdenum. Martensitic steel grades and precipitation hardening (PH) stainless steels are heat treatable and can therefore provide hardness and strength in a wide range of applications. Allowing to workability they are supplied in solution annealed condition.
The precipitation-hardened stainless steels, martensitic, niobium-stabilized chromium-nickel steels are an excellent alternative for applications where the mechanical properties and corrosion resistance of martensitic steels are not sufficient:
- are insensitive to intergranular corrosion
- are highly resistant to vibration and stress corrosion cracking
- are characterized by high mechanical strength and corrosion resistance is suitable for low temperatures
- are suitable for an operating temperature of up to approx. 350 degrees C
- can be welded in the solution-annealed condition
Typical steel in this material group: 17-4PH
Type 17-4 PH stainless steel is the most widely used of all of the precipitation-hardening
stainless steels. Typical technical properties of material 17-4-PH (+800 condition):
Yield strength: Rp0,2 = 600 MPa
Tensil strength: Rm = 900 – 1100 MPa
Hardness: HBWmax = 360
Heat treatment of 17-4PH steel
Alloy 17-4PH is provided in the solution-annealed condition (Condition A). Mechanical properties may be altered by subsequent age hardening treatments. These aging treatments are to as Conditions H900, H1025, H1075, H1150, H1150M and H1150D (depending the heat treatment temperature in °F).
Applications of precipitation-hardened stainless steels
Typical applications for martensitic stainless steel grades: fasteners, springs, press plates, seals, oil field valve equipment, chemical process equipment, part of steam and gas turbines.
Typical materials in ISO/TR 15608 material group 7.3:
| Name | Number | Standard | Product | AISI/ Trade Marks | Remarks |
|---|---|---|---|---|---|
| X5CrNiCuNb16-4 | 1.4542 | EN 10088-3 | Bar | – | – |
| X5CrNiCu15-5 15-5-PH | 1.4545 S15500 | – ASTM A-564 | – Bar | – XM-13 | – ASME BPVC |
| X5CrNi CuNb17-4-4 17-4PH | 1.4548 S17400 | EN 10088-3 +AT ASTM A-564 | – Bar | – 630 | – ASME BPVC |