Grade 631 Stainless Steel (17-7 PH)

Description

Grade 631, also known as 17-7 PH, is a precipitation-hardening (PH) austenitic-martensitic stainless steel, offering a balance of high strength, good corrosion resistance, and excellent formability. It is composed of 16.0-18.0% chromium, 6.5-7.75% nickel, and aluminum (0.75-1.50%) as the precipitation-hardening element, which allows it to be hardened through low-temperature aging. 631 has a unique microstructure that transforms from austenite to martensite when cooled, and subsequent aging precipitates aluminum-rich phases to enhance strength. It is magnetic in the martensitic state and has good weldability and formability, making it suitable for complex-shaped components. Compared to 630 (17-4 PH), 631 offers better formability and slightly lower strength, but excellent toughness and corrosion resistance in mild to moderate environments. It is widely used in applications requiring high strength, formability, and corrosion resistance, such as aerospace, automotive, and decorative components.

Chemical Composition (wt%)

C ≤ 0.09, Cr: 16.00-18.00, Ni: 6.50-7.75, Al: 0.75-1.50, Mn ≤ 1.00, Si ≤ 1.00, P ≤ 0.040, S ≤ 0.030

Mechanical Properties

Tensile Strength ≥ 795 MPa, Yield Strength ≥ 515 MPa, Elongation ≥ 15%, Hardness ≤ 248 HB (annealed); Tensile Strength ≥ 1035 MPa, Yield Strength ≥ 860 MPa, Elongation ≥ 8%, Hardness ≥ 302 HB (aged)

Advantages

High strength after aging; excellent formability (better than 630); good corrosion resistance; magnetic in martensitic state; low-temperature aging (minimizes distortion); good weldability; suitable for complex-shaped components.

Applications

Aerospace components, automotive trim and parts, springs, fasteners, decorative panels, and industrial components requiring high strength and formability.

Equivalent Grades

AISI 631 (17-7 PH), UNS S17700, EN 1.4568, GB 07Cr17Ni7Al

 

Stainless Steel Suppliers

If you have project requirements for stainless steel, we welcome your order. GNEE has a large inventory of popular products for you to choose from. It can be processed into various practical product forms, including plates, coils, tubes, bars, wires, etc. For detailed chemical composition information and free samples, please contact our factory immediately. We offer competitive prices and excellent service.Email: info@gneestainless.com

 

Testing and Documentation: Factory test certificate, EN 10204 3.1, chemical report, mechanical report, destructive testing report, non-destructive testing report, PMI test report, visual inspection report, third-party inspection report, NABL certified laboratory report.
Packaging: Wooden crate packaging, bubble wrap packaging, steel strapping, or packaging according to customer requirements.