No, i'd stick with 316L
Both of 904L and 316L are Austenite steel which are nonmagnetic and has high corrosion resistant properties, and good machining and polishing performance. As we all know, they can be be regard as substitutes for each other in some cases. So what's the difference?
Grade 316L, the low carbon version of 316, is highly resistant to sensitisation (grain boundary carbide precipitation) and so is extensively used in heavy gauge welded components. The lower carbon content of 316L gives it an even greater resistance to corrosive environments than 316 stainless steel. Austenitic stainless steel 904L is a kind of low carbon high-alloy Austenitic stainless steel with good machinability and weldability and corrosion resistance to dilute sulfuric acid. The addition of copper makes it have strong acid resistance, especially to interstitial corrosion of chloride and stress corrosion.
Chemical Composition is the the key to study and determinate the physical properties of 316L and 904L. We are indicating the chemical composition of the two analyzed SS grades we are studying in the table below.
Grade | C | Mn | Si | P | S | Cr | Mo | Ni | Cu |
316L | 0.03 | 2.0 | 0.75 | 0.045 | 0.030 | 16.0-18.0 | 2.00-3.00 | 10.0-14.0 | / |
904L | 0.02 | 2.0 | 1.00 | 0.035 | 0.035 | 19.0-23.0 | 4.0-5.0 | 23.0-28.0 | 1.0-2.0 |
As you can find in the table above, 316L and 904L steel has a similar Chemical composition in the content of C, Si and Mn, but the alloy content such as Chromium, Nickel and Molybdenum of 904L steel is much higher than 1.6 times that of 316L, and 904L steel contains a certain amount of copper, which can effectively delay the corrosion of acidic liquid, especially chloride on stainless steel, making 904L steel more resistant to corrosion and abrasion than 316L. In addition, 904L is much higher resistance to chlorides at elevated temperatures. If 904L has better corrosion resistance, Can I replace 316L with 904L? The answer is No! The higher nickel content of 904L making it is an expensive component and this will influence the overall cost .
There is no difference between 316L and 904L steel in strength and hardness. Both of them have similar Rockwell hardness (HRB) which is less than 95 and their tensile strength are both about 490MPa. These properties are specified for flat rolled product (plate, sheet and coil) in ASTM A240/A240M. The specification for pipe and bar is similar but not necessarily identical properties are specified.