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| Quantity: | |
|---|---|
| Grade | Ni | Fe | C | Mn | Si | Mo | Cu | Cr | Al | Ti | S |
| N08825 | 38.00 – 46.00 | ≥22.00 | ≤0.05 | ≤1.00 | ≤0.50 | 2.50 - 3.50 | 1.50- 3.00 | 19.50- 23.50 | ≤0.20 | 0.60 - 1.20 | ≤0.03 |
TP314 seamless stainless steel pipe and tube (UNS S31400), designated as 1.4841 in EN and X15CrNiSi25-20 in DIN, is a high-temperature austenitic alloy optimized for extreme oxidation resistance. Comprising 24-26% chromium, 19-22% nickel, 1.5-2.5% silicon, and ≤0.20% carbon, this alloy leverages elevated chromium and silicon to form a dense SiO₂-Cr₂O₃ protective layer, making it superior to standard 300-series steels in high-temperature scaling environments. Manufactured via seamless extrusion or piercing, it meets standards like ASTM A312 and EN 10216-5, ensuring dimensional precision and structural uniformity.
TP314’s microstructure remains stable under prolonged exposure to temperatures up to 1200°C, making it a critical material for applications where lower-alloyed steels would fail due to oxide spalling or carburization.
Exceptional High-Temperature Oxidation Resistance: Withstands continuous service at 1150°C and intermittent use up to 1300°C, resisting scale formation in air, combustion gases, and carburizing atmospheres better than TP310H due to its higher silicon content.
Corrosion Resistance in Oxidizing Acids: Resistant to nitric acid, chromic acid, and hot alkaline solutions, though it is less effective in reducing environments (e.g., hydrochloric acid) compared to nickel-rich alloys.
Good Mechanical Properties at Elevated Temperatures: Maintains creep strength and ductility up to 1000°C, enabling use in stress-bearing components like furnace supports and retorts.
Moderate Fabricability: Can be welded using GTAW with 314L filler metal, though preheating (150-200°C) and slow cooling are recommended to prevent hot cracking. Cold forming requires higher forces due to its increased work-hardening rate.
Industrial Furnaces: Used in radiant tubes, muffle furnaces, and heat treatment fixtures for carburizing, nitriding, and annealing processes, where exposure to 900-1200°C is common.
Cement & Glass Manufacturing: Employed in kiln liners, exhaust stacks, and glass melting furnaces, resisting alkali-induced corrosion and thermal shock.
Petrochemical Reforming: Suitable for steam reformer tubes and ethylene furnace coils operating at high temperatures with low sulfur content.
Aerospace Heat Exchangers: Used in auxiliary power units (APUs) and engine components requiring lightweight high-temperature resistance.
Q: Why is silicon added to TP314?
A:Silicon enhances the formation of a protective silica-rich oxide layer, improving scale adhesion and reducing oxidation rates at temperatures above 900°C.
Q: Can TP314 be used in sulfur-containing environments?
A:It resists mild sulfurous gases but is not recommended for high-sulfur atmospheres (e.g., coal-fired boilers), where nickel-based alloys like Inconel 601 perform better.
Q: Does TP314 require solution annealing after welding?
A:Solution annealing at 1150-1200°C is recommended for critical applications to dissolve carbides and restore uniform corrosion resistance, though it is not mandatory for non-corrosive high-temperature use.
Q: How does TP314 differ from TP310H?
A:TP314 has higher silicon (1.5-2.5% vs. ≤1.5% in TP310H) and slightly lower carbon, making it more resistant to scale spalling but less suitable for high-stress creep applications.
