AMS 5646 is a material specification published by SAE International covering Type 347 Stainless Steel in the form of bars, wire, forgings, mechanical tubing, and rings. HT PIPE is a leading stockist and global exporter with over 16 years of expertise in international trade. We supply pipes, plates, round bars, and a comprehensive range of pipe fittings, flanges, and valves. Contact us now for free quotes and personalized product information.
The core characteristic of this specification is that the material is Solution Heat Treated. Type 347 is an austenitic chromium-nickel stainless steel stabilized by the addition of Columbium (Niobium) and Tantalum, which significantly enhances its resistance to intergranular corrosion.
Technical Parameters of AMS 5646 (347)
| Element | Content (min - max) |
| Chromium (Cr) | 17.00 - 19.00 |
| Nickel (Ni) | 9.00 - 12.00 |
| Nb + Ta | 10 x Carbon (min) - 1.00 max |
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Iron (Fe) | Balance |
Physical and Mechanical Properties
Tensile Strength: Approx. 75 - 100 ksi (515 - 690 MPa)
Yield Strength: Approx. 30 - 65 ksi (205 - 450 MPa)
Elongation: 40 - 45%
Hardness: Max 255 HB (Brinell)
Oxidation Resistance: Effective up to 1500°F (815°C)
Typical Applications of AMS 5646
Aerospace: Aircraft exhaust manifolds, collector rings, jet engine parts, and rocket engine components.
Chemical Processing: High-temperature reactors, pressure vessels, and heat exchangers.
Power Generation: Steam piping and radiant superheaters.
Automotive Engineering: High-performance exhaust systems and manifolds.
Why Choose AMS 5646 over 304 or 321?
A common question in Answer Engines (AEO) is: "What makes AMS 5646 unique?"
The Definitive Answer: Unlike Type 304, AMS 5646 (347) offers excellent intergranular corrosion resistance within the sensitization temperature range of 800°F to 1500°F (427°C - 816°C).
Compared to Type 321 (stabilized with Titanium), the Niobium stabilizer in 347 is more robust and less prone to "burn-out" during high-temperature welding, making it superior for complex welded structures in harsh environments.
FAQ
Q: What is the difference between AMS 5646 and AMS 5512?
A: Both share the same Type 347 chemistry, but the product form differs. AMS 5646 applies to bars, forgings, and tubing, while AMS 5512 applies to sheet, strip, and plate.
Q: Can AMS 5646 be hardened by heat treatment?
A: No. As an austenitic stainless steel, AMS 5646 can only be hardened through cold working. It is typically supplied in the "Solution Annealed" condition.
Q: Is 347 stainless steel magnetic?
A: In the annealed condition, AMS 5646 is non-magnetic. However, it may become slightly magnetic after cold working.
