Sae 904l Stainless Steel
It has almost the identical bodily and mechanical properties as 304 stainless steel, and contains a similar material make-up. The key difference is that 316 stainless steel incorporates about 2 to 3 percent molybdenum.
In 2003 their whole production line modified to 904L, though it was as early as 1988 that they launched their first 904L steel watch with a number of versions of the Sea-Dweller. Grade 904L stainless steels are high purity steels with low sulphur content. These grades could be readily bent to a small radius under chilly conditions. Although subsequent annealing is not required in most cases, it must be carried out when the fabrication is performed under severe stress corrosion cracking circumstances. The corrosion resistance of grade 904L is intermediate between tremendous austenitic grades, with 6% molybdenum content, and standard 316L austenitic grades.
- Rolex calls 904L stainless steel a “corrosion-resistant superalloy.” 904L differs from 316L because of further Chromium, Molybdenum, Nickel, and Copper that gives it improved resistance to acids.
- After casting and inspection, the steel is then re-melted in a vacuum to purify it and remove any inclusions that might diminish its corrosion resistance and lead to problems in sprucing.
- The two grades of stainless-steel most referenced in relation to outdoor environments are 304 and 316L, also called marine-grade stainless steel.
- Unlike the lively metals talked about above, stainless-steel is referred to as passive as a result of it incorporates different metals including chromium.
- 316L is considered a harder, tougher, “marine grade” steel, but it does not have luster and acid resistance of Rolex’s 904L stainless steel.
Stainless steel manufacturer />
Is 904l better than 316l?
The 316L Stainless steel is far less scratch resistant than the 904L because it has a much higher Rockwell hardness. The main advantage of 904L over 316L is its resistance to acids: “The addition of copper to this grade gives it greatly improved resistance to strong reducing acids, particularly sulphuric acid.”
The key difference is the addition of molybdenum, an alloy which drastically enhances corrosion resistance, especially for extra saline or chloride-exposed environments. Nowadays, most chrome steel wristwatches are made of 316L stainless-steel, and for a time, so was Rolex. Even though 316L steel was created in order to stop rust and pits from salt water and sweat, Rolex was finding extra wear within the case back threads and watch case. Salt and other minerals are the catalysts wanted for corrosion and deterioration of the threads holding the case again. They could clearly see that gold and platinum watches didn’t have this corrosion issue, so it wanted fixing.
In 1985 Rolex became the first wristwatch manufacturer to make the most of 904L grade steel in its watches. 316 grade is the second-commonest type of stainless steel.
Grade 904L is less immune to nitric acid than grades 304L and 310L, that are freed from molybdenum. This steel grade needs to be answer treated following cold working, to attain most stress corrosion cracking resistance underneath critical environments.
The high resistance of grade 904L towards stress corrosion cracking is because of the presence of high quantities of nickel in its composition. Moreover, the addition of copper to those grades develops resistance to sulphuric acid and different decreasing agents in each aggressive and mild circumstances. Both 304 and 316 stainless steels (in addition to different 300-sequence grades) use nickel to maintain an austenitic composition at decrease temperatures.