904L stainless steel pipe

904L stainless steel pipe is a high-alloy, super-austenitic stainless steel pipe with copper added to the stainless steel alloy. Therefore, it has a strong resistance to strong reducing acids such as sulfuric acid and is widely used in corrosive and harsh environments such as chemical engineering, Marine, and aviation. The following is a detailed introduction from aspects such as chemical composition, performance characteristics, processing, standards and applications:

The carbon content of 904L stainless steel pipes is relatively low. The low carbon content makes AISI 904L welded pipes easier to be manufactured in accordance with ASTM A312 specifications. The following is its detailed chemical composition:

Carbon C ≤ 0.02%
Chromium (Cr) 19-23%
Nickel Ni 23-28%
Molybdenum (Mo) 4-5%
Copper Cu 1-2%
Manganese Mn ≤ 2%; Silicon Si ≤ 1%; Nitrogen N ≈ 0.1-0.15%.

Compared with 316L and 317L, 904L has increased the content of nickel, molybdenum and copper, significantly enhancing its resistance to local corrosion, cracking and acid. Despite having a lower carbon content, these steel pipes can still be used in high-temperature applications.

Performance characteristics

Corrosion resistance

It has excellent resistance to reducing acids such as sulfuric acid, phosphoric acid and acetic acid.

It has excellent resistance to pitting corrosion, crevice corrosion and stress corrosion of chlorides, which is significantly better than 316L/317L.

The low carbon content inhibits welding sensitization and intergranular corrosion.

(2) Mechanical and physical properties

Yield strength ≈ 240-313 MPa, tensile strength ≈ 520-730 MPa.

Elongation ≥ 35-40%, good low-temperature toughness, impact value > 100 J/cm² at -196  °C.

Non-magnetic (all austenite), density ≈ 7.95-8.05 g/cm³.

Low thermal conductivity (≈ 12-17 W/m·K), elastic modulus ≈ 190 GPa.

(3) Processing performance

The welding quality is good and can be processed by standard techniques such as TIG/MIG. Usually, no further heat treatment is required. It is necessary to control the heat input and interlayer temperature, and select nickel-based fillers.

When cutting workpieces that are prone to hardening, slow speed, sharp tools, high lubrication and continuous cutting are required.

It is easy to draw tubes and form them, and has good plasticity.

Standard specification

UNS N08904, EN 1.4539 (X1NiCrMoCu25-20-5).
Multiple ASTM and ASME standards: such as B625, B674, B677, SA213, SA269, etc.

Common product forms include:

Specification: OD 6-325 mm, wall thickness 0.5-20 mm, length up to 12 m.
Common conditions: cold-drawn bright tubes, electro-polished tubes, seamless or welded structures.

Application field:

Chemical processing
Food processing - equipment and storage
Petroleum refining - fluidized bed catalytic cracking unit, polysulfuric acid service
Pharmaceutical production
Waste heat recovery - heat exchanger
Wiring in the electrostatic precipitator
Refinery components
Seawater cooling device
Gas washing device
Pulp and paper processing industry
Acetic acid, phosphoric acid and sulfuric acid processing plants

Central Steel has a complete inventory of 904L stainless steel pipes and tubing, supplying austenitic chromium-nickel stainless steel pipes suitable for corrosive or high-temperature services (or both) or general applications.