AISI 347 stainless steel is a niobium-stabilized austenitic alloy designed for high-temperature service and resistance to intergranular corrosion. It maintains strength and oxidation resistance up to 870 °C and provides superior weldability compared to other Cr–Ni grades. Its chemical composition—approximately 18% Cr, 10% Ni, and trace Nb—ensures stable carbide formation and reduced sensitization during thermal cycling.
Material Overview
The microstructure of AISI 347 is fully austenitic (face-centered cubic), with niobium forming stable NbC and NbCN precipitates that inhibit chromium carbide formation along grain boundaries. This promotes exceptional resistance to intergranular attack and sensitization (Peng et al., 2025). At room temperature, the alloy exhibits a tensile strength of approximately 515 MPa, yield strength near 205 MPa, and elongation of 40%. Its thermal conductivity is about 16 W·m⁻¹·K⁻¹ at 100 °C, and the coefficient of thermal expansion averages 16×10?? K?¹. Studies on the oxidation of AISI 347 in air and K?SO?–NaCl mixtures at 700 °C revealed stable, protective Cr?O? scales, though chloride exposure promotes oxide spallation (Muthu et al., 2020). Veile et al. (2024) confirmed that the alloy forms dual-layer oxides—an inner Cr-rich protective layer and an outer Fe-rich oxide—with minimal chromium depletion even after 480 h at 550 °C.
Applications and Advantages
AISI 347 stainless steel is widely used in heat exchangers, furnace parts, pressure vessels, and nuclear and chemical plant components. The addition of niobium enhances resistance to sensitization during welding and long-term exposure at elevated temperatures, outperforming similar alloys such as AISI 304 and 321. Heat treatment at 1050 °C followed by air cooling improves passive film integrity and reduces oxidation rates by stabilizing compact Cr–Nb oxides (Peng et al., 2025). Under cyclic thermal exposure, AISI 347H demonstrates consistent oxidation behavior up to 1000 °C with limited scale growth, maintaining mechanical and chemical reliability in aggressive environments.
Goodfellow Availability
Goodfellow offers AISI 347 stainless steel in research and engineering forms suitable for high-temperature, corrosive, and mechanically demanding applications. Custom sizes and processing options are available upon request. Explore stainless steels and advanced alloys through the Goodfellow product finder.
References
- Peng, Y., Zhao, B., Yang, J., Bai, F., Qian, H., Shi, B., & Wang, L. (2025). Study the effect of heat treatment on the corrosion resistance of AISI 347H stainless steel. Materials, 18(15), 3486. https://doi.org/10.3390/ma18153486
- Muthu, S. M., Venkateshkannan, M., Gupta, S., Prakash, K. S., Arivarasu, M., & Arivazhagan, N. (2020). Investigation of air oxidation and hot corrosion behavior of AISI 347. Materials Today: Proceedings, 27, 1238–1244. https://doi.org/10.1016/j.matpr.2020.02.187
- Veile, G., Hirpara, R., Lackmann, S., & Weihe, S. (2024). Investigation of oxide layer development of X6CrNiNb18-10 stainless steel exposed to high-temperature water. Materials, 17(18), 4500. https://doi.org/10.3390/ma17184500
- Inoue, Y., Hiraide, N., & Ushioda, K. (2016). Effect of Si addition on oxidation behavior of Nb-containing ferritic stainless steel. Tetsu-to-Hagane, 102(5), 329–336. https://doi.org/10.2355/TETSUTOHAGANE.TETSU-2016-023