1. **What is the meaning of ASTM 304?**
ASTM 304 refers to a grade of stainless steel defined by the ASTM International standards organization. It is part of the 300 series austenitic stainless steels, known for its good corrosion resistance, formability, and weldability. The "304" designation indicates its composition, primarily 18% chromium and 8% nickel (18-8 stainless steel).
2. **Can you use 304 and 316 stainless steel together?**
Yes, 304 and 316 stainless steel can be used together in many applications. They are both austenitic stainless steels with similar mechanical properties and are often compatible in terms of thermal expansion and welding. However, in highly corrosive environments (e.g., chloride exposure), 316's superior corrosion resistance may lead to uneven degradation over time.
3. **What is more expensive, 304 or 316 stainless?**
316 stainless steel is generally more expensive than 304 due to its higher nickel content and the addition of molybdenum (2-3%), which enhances corrosion resistance, particularly against chlorides and acids.
4. **Can I weld 304 stainless to 316?**
Yes, 304 and 316 stainless steels can be welded together using common methods like TIG or MIG welding. They have similar thermal properties, and filler metals such as 308L or 316L are often used to ensure a strong, corrosion-resistant joint.
5. **Is there galvanic corrosion between 304 and 316?**
No, significant galvanic corrosion is unlikely between 304 and 316 stainless steels because their electrode potentials are very similar. Both are part of the same "cathodic" group, so galvanic effects are minimal in most environments. However, in extreme conditions (e.g., submerged in saltwater), minor localized corrosion could occur, but it's rarely a practical concern.
