Duplex stainless steel pipe has better corrosion resistance than austenitic stainless steel pipe, and its practicability is wider. Because of ferrite structure in duplex stainless steel pipe, it has both the properties of ferrite and austenitic stainless steel pipe.
The advantages of duplex stainless steel pipes are many. First, the yield strength is much higher than that of ordinary austenitic stainless steel pipes, and there is enough plastic and toughness for forming dual phase stainless steel pipes. The wall thickness of a dual phase stainless steel pipe or pressure vessel is reduced by 30%~50% than that of austenitic stainless steel, which reduces most of the cost.
The duplex stainless steel pipe resistance to stress corrosion cracking ability is outstanding, especially in chloride environment, even if the resistance to stress corrosion cracking ability is stronger than the austenitic stainless steel pipe alloy containing the lowest amount of duplex stainless steel, and stress corrosion can be said to be very difficult to solve the problems of ordinary austenitic stainless steel pipe.
In some media, such as acetic acid and formic acid, the corrosion resistance of duplex stainless steel pipes can even replace high alloy austenitic stainless steel pipes, or even part of corrosion resistant alloy pipes.
The double phase stainless steel pipe also has excellent resistance to localized corrosion and similar alloy content of austenitic stainless steel pipe as compared to duplex stainless steel pipe with high strength and good corrosion resistance, wear resistance corrosion and corrosion fatigue properties are more excellent than the austenitic stainless steel pipe.
The coefficient of linear expansion of dual phase stainless steel pipe is lower than that of austenitic stainless steel pipe, close to carbon steel pipe, and suitable for joining with carbon steel pipe. Engineering significance is very important, for example, producing composite panels or linings.
In addition, the energy absorption capacity of the dual phase stainless steel pipe is better than the austenitic stainless steel pipe, regardless of the dynamic load or the static load. This is of obvious advantage to the duplex stainless steel pipe, such as collision and explosion, and its practical application value is higher.
But the duplex stainless steel pipes also have some disadvantages. For example, the universality and multifaceted nature of the duplex stainless steel pipes are not as good as those of the austenitic stainless steel pipes. For example, the application temperature of the duplex stainless steel pipes must be controlled below 250 degrees.
Secondly, the ductility of the dual phase stainless steel pipe is lower than the austenitic stainless steel pipe, and the cold, hot processing technology and the molding performance are inferior to the austenitic stainless steel pipe.
Moreover, the duplex stainless steel pipe has moderate temperature brittle area. We must strictly control the heat treatment and welding process system to prevent the occurrence of harmful phase and damage the performance of duplex stainless steel pipe.
Source: China Duplex Stainless Steel Pipes Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)