1. Compared with 304
stainless steel pipe, the advantages of duplex stainless steel pipe are as follows:
(1) The yield strength is more than double that of ordinary austenitic stainless steel pipe, and it has sufficient plastic toughness required for forming. The wall thickness of storage tanks or pressure vessels made of duplex stainless steel pipe is 30-50% lower than that of commonly used austenite, which is conducive to reducing costs.
(2) It has excellent resistance to stress corrosion cracking. Even duplex stainless steels pipe with alloy content have higher resistance to stress corrosion cracking than austenitic stainless steel pipe, especially in environments containing chloride ions. Stress corrosion is a prominent problem that ordinary austenitic stainless steel is difficult to solve.
(3) The corrosion resistance of the most commonly used 2205 duplex stainless steel pipe in many media is better than that of ordinary 316L austenitic stainless steel pipe, while the super duplex stainless steel pipe has extremely high corrosion resistance, and in some media, such as acetic acid, Formic acid, etc. can even replace high-alloy austenitic stainless steel pipe, and even corrosion-resistant alloys.
(4) It has good local corrosion resistance. Compared with austenitic stainless steel
pipe with equivalent alloy content, its wear corrosion resistance and fatigue corrosion resistance are better than austenitic stainless steel.
(5) The linear expansion coefficient of austenitic stainless steel
pipe is lower than that of austenitic stainless steel
pipe, which is close to that of carbon steel. It is suitable for connecting with carbon steel and has important engineering significance, such as the production of clad plates or linings.
(6) Whether under dynamic load or static load conditions, it has higher energy absorption capacity than austenitic stainless steel
pipe, which has obvious advantages for structural parts to cope with sudden accidents such as collision, explosion, etc., and has practical application value.
2. Compared with 304 stainless steel
pipe, the disadvantages of duplex stainless steel pipe are as follows:
(1) The universality and versatility of application are not as good as that of austenitic stainless steel
pipe. For example, its use temperature must be controlled below 250 degrees Celsius.
(2) Its plasticity and toughness are lower than that of austenitic stainless steel
pipe, and its cold and hot working processes and forming properties are not as good as that of austenitic stainless steel
pipe.
(3) There is a medium temperature brittle zone, and it is necessary to strictly control the processing system of heat treatment and welding to avoid the appearance of harmful phases and damage the performance.
After understanding the differences between these parts, I believe that there will be some different understandings of stainless steel pipe products.
