TECHNICAL SPECIFICATION

904L is a high-alloy austenitic stainless steel with low carbon content. The grade is intended for use under severe corrosive conditions. It has been application proved over many years and was originally developed to resist corrosion in dilute sulfuric acid. It is standardized and approved for pressure vessel use in several countries. Structurally, 904 L is fully austenitic and is less sensitive to precipitation ferrite and sigma phases than conventional austenitic grades with high molybdenum content. Characteristically, due to the combination of relatively high contents of chromium, nickel, molybdenum and copper 904L has good resistance to general corrosion, particularly in sulfuric and phosphoric conditions.

Machinability
Slow speeds and positive feeds will minimize this alloy's tendency to work harden and glaze. Use chip breakers where possible to overcome problems with long draggy chips.

Welding
Most common fusion and resistance methods may be employed. For maximum corrosion resistance, it is recommended to use filler metals of equal or higher alloy content.

Hot Working
Hot work should proceed after uniform heating to 2000-2200 F. Doe not work the material at less than 1800 F. Full annealing should follow any hot work to re attain maximum ductility and corrosion resistance.

Cold Working
Although higher forces are required, 904L will respond in a similar fashion to other austenitic stainless steels like 304, 316 or 317. Most common operations can be successfully performed.

Annealing
1920-1990 F ( 1050-1090 C ), rapid cooling.

Hardening
This alloy does not respond to heat treatment.. It may only be hardened by cold reduction.

DESIGN FEATURES
Good resistance to pitting and crevice corrosion.
Very good resistance to stress corrosion cracking.
Good resistance to intergranular corrosion.
Good formability and weldability.
Maximum service temperatures of
450 deg.C. (824 deg.F).

TYPICAL APPLICATIONS