904L stainless steel consists of chromium, nickel, molybdenum and copper contents, these elements give type 904L stainless steel excellent properties to resist corrosion in dilute sulfuric acid because of addition of copper, 904L commonly is used in high pressure and corrosion environment where 316L and 317L perform poorly. 904L has high nickel composition with low carbon content, copper alloy adding improve its resistance to corrosion, the “L” in 904L stands for low carbon, it is typical Super Austenitic stainless steel, equivalent grades are DIN 1.4539 and UNS N08904, 904L has better properties than other austenitic stainless steels.
Chemical Composition (Max %) of 904L Stainless Steel
| Grade | Ni | Cr | Mo | Cu | C | Mn | Si | P | S | Fe |
|---|---|---|---|---|---|---|---|---|---|---|
| 904L | 23 – 28 | 19 – 23 | 4 -5 | 1 – 2 | 0.02 | 2 | 1 | 0.045 | 0.035 | Balance |
Mechanical Properties of 904L Stainless Steel
| Grade | Tensile Strength, Min | Yeild Strength, Min | Elognation | Hardness |
|---|---|---|---|---|
| 904L | 490 Mpa | 215 Mpa | 0.35 | 90 HRB Max |
904L Stainless Steel Properties
- Excellent resistance to stress corrosion cracking due to the presence of high amounts of nickel content.
- Pitting and crevice corrosion, intergranular corrosion resistance.
- Grade 904L is less resistant to nitric acid.
- Excellent formability, toughness and weldability, due to low carbon composition, it can be welded using any standard method, 904L cannot be hardened by heat treatment.
- Non-magnetic, 904L is an Austenitic stainless steel, therefor 904L possesses Austenitic structure properties.
- Heat Resistance, Grade 904L stainless steels offer good oxidation resistance. However, the structural stability of this grade collapses at high temperatures, particularly above 400°C.
- Heat Treatment, Grade 904L stainless steels can be solution heat-treated at 1090 to 1175°C, following by rapid cooling. Thermal treatment is suitable for hardening these grades.
904L Stainless Steel Limitation
904L stainless steel price is expensive, due to high amount of molybdenum and nickel content, that leads to grade 904L is replaced by low cost grades, such as 316L, 317L, 2205, 6Mo and super duplex grades.
904L Stainless Steel Pipe Standards
- ASTM A 312 – seamless, welded, and heavily cold worked austenitic stainless steel pipes
- ASTM B 673 – uns n08904, uns n08925, and uns n08926 welded pipe
- ASTM B 677 – uns n08904, uns n08925, and uns n08926 seamless pipe and tube
904L Stainless Steel Tube Standards
- ASTM A 213 – seamless ferritic and austenitic alloy-steel boiler, super heater, and heat-exchanger tubes
- ASTM A 249 – welded austenitic steel boiler, super heater, heat-exchanger, and condenser tubes
- ASTM A 269 – seamless and welded austenitic stainless steel tubing for general service
- ASTM B 674 – uns n08904, uns n08925, and uns n08926 welded tube
- ASTM B 677 – uns n08904, uns n08925, and uns n08926 seamless pipe and tube
904L Stainless Steel Applications
Because of above properties, 904L stainless steel pipe can be used in many applications, these range from utility scrubber assemblies to acid and fertilizer production equipment, pulp and paper processing, seawater cooling facilities. Used in processes containing sulfuric or phosphoric acids, 904L displays its excellent resistance to corrosion from those acids. The paper, gas, pharmaceutical and chemical industries also use 904L for its resistance and use to 400-450 degrees C. Alloy 904L tubing can be welded, machined, heat treated, annealed, hardened and cold worked for many purposes.
- Petroleum and petrochemical equipment, for example: Reactor
- Storage and transportation equipment of sulphuric acid, for example: heat exchanger
- Sea water treatment equipment, sea water heat exchanger
- Paper industry equipment, sulfuric acid, nitric acid equipment, making acid, pharmaceutical industry
- Pressure vessel
- Food equipment