What is 1.4545 Stainless Steel?

1.4545 stainless steel, commonly known as XM-12 or 15-5PH (UNS S15500), is a martensitic precipitation-hardening stainless steel similar to 17-4PH but with slightly different composition to enhance toughness and transverse mechanical properties. It is known for its high strength, good corrosion resistance comparable to Type 304, and excellent toughness in both longitudinal and transverse directions, making it ideal for aerospace, chemical, and high-performance engineering components.

 

This high-strength precipitation-hardening grade is standardized under key international systems.

Standard	Equivalent Grade
EN (Europe)	1.4545
ASTM/AISI (USA)	15-5PH, UNS S15500 (XM-12)
Common Name	15-5PH, XM-12

Its composition includes chromium, nickel, copper, and niobium/columbium for precipitation hardening.

Element	C	Si	Mn	Cr	Ni	Cu	Nb+Ta
Content (%)	≤ 0.07	≤ 1.0	≤ 1.0	14.0 - 15.5	3.5 - 5.5	2.5 - 4.5	0.15 - 0.45

Mechanical properties vary with heat treatment condition (e.g., Condition A, H900, H1150).

Condition	Yield Strength (Rp0.2)	Tensile Strength (Rm)	Elongation (A)	Hardness (HRC)
Solution Treated (A)	~ 690 MPa	~ 1000 MPa	~ 15%	~ 32 HRC
H900	~ 1170 MPa	~ 1310 MPa	~ 10%	~ 44 HRC
H1150	~ 790 MPa	~ 1000 MPa	~ 12%	~ 33 HRC

 

Key Characteristics and Applications of 1.4545 / 15-5PH

High Strength with Excellent Toughness: Offers tensile strengths over 1300 MPa after aging, with superior toughness and ductility compared to many other high-strength stainless steels, especially in the transverse direction.

Good Corrosion Resistance: Provides corrosion resistance similar to Type 304 stainless steel, suitable for moderately corrosive environments.

Precipitation Hardening: Can be machined in the solution-treated (softer) condition and then aged to high strength with minimal distortion.

 

Primary Applications:

Aerospace: Landing gear components, turbine blades, fasteners, and structural parts requiring high strength-to-weight ratio.

Chemical & Petrochemical: Valves, pump shafts, and fittings exposed to corrosive media.

Oil & Gas: Downhole tools, instrumentation components, and high-pressure valves.

Medical: Surgical instruments and orthopedic implants requiring strength and biocompatibility.

 

What is the difference between 15-5PH (1.4545) and 17-4PH (1.4542)?
Both are precipitation-hardening martensitic stainless steels, but 15-5PH has slightly lower chromium (14–15.5% vs. 15–17.5%) and higher nickel content. This composition adjustment, along with vacuum melting practices typically used for 15-5PH, results in cleaner steel with fewer inclusions, giving 15-5PH significantly better transverse toughness and ductility. 15-5PH is often chosen for critical aerospace and medical applications where isotropic properties are essential.

 

How is 15-5PH typically heat treated?
The standard heat treatment involves solution treating at 1038°C ± 15°C, followed by rapid cooling (air or oil quench) to achieve Condition A (soft, machinable state). It is then aged at a specific temperature (e.g., 482°C for H900, 621°C for H1150) to precipitate hardening phases and achieve the desired strength and toughness. Double aging is sometimes used to optimize properties and ensure dimensional stability.

 

Looking for a Reliable Supplier of 1.4545 / 15-5PH Stainless Steel?
GNEE Steel supplies high-performance 15-5PH (1.4545) stainless steel in bar, plate, and forging forms, available in various heat-treated conditions to meet demanding aerospace and industrial specifications. We provide full material certification and processing support. If you have any requirements, please feel free to contact us.