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, and it has sufficient plastic toughness required for forming. The wall thickness of storage tanks or pressure vessels made of duplex stainless steel 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 steel with alloy content has a higher resistance to stress corrosion cracking than austenitic stainless steel, especially in an environment 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 in many media is better than that of ordinary 316L austenitic stainless steel, while the super duplex stainless steel has extremely high corrosion resistance, and in some media, such as acetic acid, Formic acid, etc. can even replace high-alloy austenitic stainless steel, and even corrosion-resistant alloys.
(4) It has good local corrosion resistance. Compared with austenitic stainless steel with equivalent alloy content, its wear corrosion resistance and fatigue corrosion resistance are better than austenitic stainless steel.
(5) The coefficient of linear expansion is lower than that of austenitic stainless steel, 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, 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, the disadvantages of duplex stainless steel are as follows:
(1) The universality and versatility of application are not as good as that of austenitic stainless steel. 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, and its cold and hot working processes and forming properties are not as good as that of austenitic stainless steel.
(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 to the performance.