Grade 904L stainless steel is a low-carbon, non-stabilized austenitic stainless steel. This high alloy stainless steel is added with copper to enhance its tolerance to strong reducing acids, such as sulphuric acid. Steel is also resistant to stress corrosion cracking and crevice corrosion. SS 904L is non-magnetic and provides outstanding formability, strength and weldability. Grade 904L contains high quantities of expensive ingredients, such as molybdenum and nickel.
Grade SMO 254 is a very high-end austenitic stainless steel. It is developed with a combination of impact strength resistance to chloride stress corrosion cracking and pitting and crevice corrosion with a strength that is twice that of the 300 series of stainless steel. For some applications, grade 254 SMO has been reported to be a cost-effective substitute for high nickel and titanium alloys. It is also known to possess excellent workability.
Corrosion Resistance of SS 904L VS SMO 254
Stainless Steel 904L Heat Exchanger Tubes has outstanding tolerance to warm seawater and chloride attacks. The excellent tolerance of grade 904L to stress corrosion cracking is attributed to the existence of high levels of nickel in its composition. Moreover, the addition of copper to these grades provides tolerance to sulphuric acid and other reducing agents under both severe and moderate environments.
Stainless Steel 904L needs to be treated following cold working to achieve maximum resistance to corrosion cracking stress in critical environments.
Heat Resistance of SS 904L VS SMO 254
Stainless Steel 904L provides a strong resistance to oxidation. However, the structural stability of this grade breaks down at high temperatures, especially above 400 degrees C. Stainless Steel 904L can be a heat-treated solution at 1090 to 1175 degrees C, followed by rapid cooling. Thermal treatment is suitable for the hardening of these grades.
Forging, upsetting and other operations related to SMO 254 may be performed at 982-1149 degrees C (1800-2100 degrees F). It is suggested that temperatures do not exceed this range, as this would lead in scaling and reduced workability of the material. It is recommended to perform post-process annealing to restore the highest corrosion-resistant characteristics.
Welding of SS 904L VS SMO 254
Stainless Steel 904L welding can be conducted using all conventional techniques. SS 904L does not require pre-heat and post-weld heat treatment. Grade 904L can be subjected to hot cracking in constrained welding. Grade 904L electrodes and rods are used for welding grade 904L steels as defined in AS 1554.6.
Welding of SMO 254 Stainless steel requires filler material without which it has poor strength properties. Filler Metal such as AWS A5.14 ERNiCrMo-3 and alloy 625 are suggested. Electrodes used in the process must comply with AWS A5.11 ENiCrMo-12.
Fabrication of SS 904L VS SMO 254
Stainless Steel 904L is high-quality steel with low sulphur content. They can be machined using any standard method. This grades can be quickly bent to a small radius under cold conditions. Even though subsequent annealing is not required in most cases, it should be performed when manufacturing under severe stress corrosion cracking conditions.
Whereas SMO 254 Stainless steel is very hard to machine due to the incredibly high work hardening rate and the lack of sulphur content; however, the usage of sharp tools, overpowered machine equipment, positive feeds, a reasonable amount of lubrication and slow speed helps to yield decent machining results.
Applications of SS 904L VS SMO 254
Some of the major applications of Stainless Steel 904L include Process equipment in the chemical industry, Petrochemical industry, Bleaching equipment in the pulp and paper industry, Flue gas cleaning, Desalination, Seawater handling, Hydrometallurgy, Food and Beverage, Pharmaceuticals, Heat exchangers, etc.
SMO 254 Stainless steel tubes are used in the various applications and industries like Saltwater handling, Tall oil distillation columns, Flue gas desulfurization scrubbers, Components used in petroleum production, Food processing equipment, Process equipment in the chemical industry, Bleaching equipment in the pulp and paper industry, Flue-gas cleaning, Desalination, etc.