ThePipingMart Blog Grades AISI 348H Stainless Steel (UNS S34809) – Composition, Properties and Uses

AISI 348H Stainless Steel (UNS S34809) – Composition, Properties and Uses

348H Stainless Steel

If you’re in the market for a durable and corrosion-resistant material, then 348H stainless steel is an excellent choice. This grade of stainless steel is widely used in industries like oil & gas, petrochemical, construction, and defence. But what makes it so special? Let’s take a look at some of the unique composition, physical properties, mechanical properties, and uses of 348H stainless steel.

348H Stainless Steel Composition

AISI 348H Stainless Steel (UNS S34809) has high carbon content, which gives it superior properties compared to other grades of stainless steel. It has a minimum chromium content of 16% by mass, with nitrogen and carbon added to enhance its strength. The presence of molybdenum increases the resistance to pitting corrosion, while chromium enhances its hardness. Furthermore, titanium is added as an austenitic stabilizer which improves its weldability and heat resistance. Additionally, this grade also has good formability and toughness due to its excellent workability characteristics.

Element Content (%)
Iron, Fe 66
Chromium, Cr 19
Nickel, Ni 11
Manganese, Mn 2.0
Silicon, Si 1.0
Nb + Ta 0.8
Cobalt, Co 0.2
Tantalum, Ta 0.1
Carbon, C 0.080
Phosphorous, P 0.045
Sulfur, S 0.030

348H Stainless Steel Physical Properties

The physical properties of materials come into play for many uses. Natural materials, such as wood, differ from synthetic materials, such as plastic, in their stiffness, durability and water absorption properties. For instance, a wooden boardwalk is a good choice for use near the water since it absorbs some of the moisture that could create slippery surfaces if using a synthetic material. Additionally, certain physical properties make certain materials ideal for specific tasks. Stiffer materials are well suited for use as a building material, while softer ones are better for making articles of clothing. Knowing the physical properties is essential to be able to choose the right material or product based on its ultimate goal and put them to proper use in everyday life.

Properties Metric Imperial
Density 8 g/cm3 0.289 lb/in³
Melting point 1427°C 2600°F

348H Stainless Steel Mechanical Properties

348H stainless steel has excellent mechanical properties, such as high tensile strength (up to 900 MPa), which makes it ideal for applications that require higher stress levels or pressure vessels operating at extreme temperatures. Its yield strength ranges from 500-800 MPa, which also makes it suitable for structural components that need extra strength, such as bridges and buildings. Moreover, this grade offers good fatigue resistance due to its low modulus of elasticity which reduces deflections under repeated loads or cyclic loading conditions.

Properties Metric Imperial
Tensile strength 655 MPa 95000 psi
Yield strength (@ strain 0.200%) 275 MPa 39900 psi
Izod impact 120 – 160 J 88.5 – 118 ft-lb
Charpy impact 160 J 118 ft-lb
Shear modulus (typical for steel) 77.0 GPa 11200 ksi
Elastic modulus 190-210 GPa 27557-30458 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30
Elongation at break (in 50 mm) 45% 45%
Hardness, Brinell (converted from Rockwell B hardness) 147 147
Hardness, Knoop (converted from Rockwell B hardness) 164 164
Hardness, Rockwell B 85 85
Hardness, Vickers (converted from Rockwell B hardness) 169 169


348H Stainless Steel Thermal Properties

Properties Metric Imperial
Thermal expansion co-efficient ( @ 0-100°C/32-212°F) 17.3 µm/m°C 9.61 µin/in°F
Thermal conductivity (@ 100°C/212°F) 16.3 W/mK 113 BTU in/hr.ft².°F

348H Stainless Steel Equivalent

ASTM A167 ASTM A312 ASTM A479 QQ S766 ASME SA376
ASTM A249 ASTM A376 ASTM A814 ASME SA249 MIL-S-23196
ASTM A269 ASTM A403 DIN 1.4550 ASME SA312 SAE 30348
ASTM A276 ASTM A409 MIL S-23195 ASME SA358 SAE J405 (30348)


348H stainless steel is one of the most popular grades in the market because of its wide range of applications across many different industries, including architecture & construction projects; automotive parts; oil & gas pipelines; furniture; kitchenware; medical equipment; as well as energy storage systems such as solar panels or wind turbines. It’s also widely used in chemical processing plants due to its ability to resist various corrosive elements like sulfuric acid and chlorides in water or airborne pollutants like smoke or dust particles which can cause oxidation on other types of metal surfaces over time. Additionally, this grade offers excellent weldability making it easy to fabricate into complex shapes without any loss in quality after the welding processes are completed.


In conclusion, 348H stainless steel is an incredibly versatile material that can be used for a variety of applications across different industries due to its durability and corrosion resistance properties combined with good formability and toughness characteristics provided by titanium stabilization agents during production processes. Its various physical properties make it ideal for use in projects requiring extra strength or operating at extreme temperatures, while its mechanical properties provide good fatigue resistance under repeated loads or cyclic loading conditions, making it perfect for structural components such as bridges or buildings too! For these reasons, 348H stainless steel remains one of the most popular grades available on the market today!

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