1. Compared with austenitic stainless steel
1) The yield strength of duplex stainless steel is more than double that of ordinary austenitic stainless steel, and it has sufficient plastic toughness required for forming. The thickness of storage tanks or pressure vessels made of duplex stainless steel is 30-50% less than that of commonly used austenitic stainless steel, which is conducive to reducing costs.
2) It has excellent resistance to stress corrosion cracking, especially in chloride ion environments. Even duplex stainless steel with the lowest alloy content has higher resistance to stress corrosion cracking than austenitic stainless steel. Stress corrosion is a prominent problem that ordinary austenitic stainless steel is difficult to solve.
3) The corrosion resistance of the most common 2205 duplex stainless steel in many media is better than that of ordinary 316L austenitic stainless steel, and super duplex stainless steel has extremely high corrosion resistance. In some media, such as acetic acid and formic acid, it can even replace high-alloy austenitic stainless steel and even corrosion-resistant alloys.
4) It has good resistance to local corrosion. Compared with austenitic stainless steel with the same alloy content, its wear corrosion resistance and corrosion fatigue performance are better than austenitic stainless steel.
5) The linear expansion coefficient is lower than that of austenitic stainless steel, close to that of carbon steel, suitable for connection with carbon steel, and has important engineering significance, such as the production of composite plates or linings.
2. Compared with ferritic stainless steel, duplex stainless steel has the following advantages:
1) The comprehensive mechanical properties are higher than those of ferritic stainless steel, especially plastic toughness. It is not as sensitive to brittleness as ferritic stainless steel.
2) Except for stress corrosion resistance, other local corrosion resistance is better than ferritic stainless steel.
3) Cold processing performance and cold forming performance are far better than ferritic stainless steel.
4) The welding performance is far better than ferritic stainless steel. Generally, no preheating is required before welding and no heat treatment is required after welding.
5) The application range is wider than ferritic stainless steel.
