High-performance ferritic stainless steel tubes have a complete ferrite microstructure in addition to a small amount of stabilized carbides and nitrides. The unique characteristic of this ferrite structure is its excellent resistance to chloride stress corrosion cracking, but its toughness is limited. The large section or grain effect and the precipitation of the brittle secondary phase further reduce its toughness. Due to limited toughness, these steel grades are usually not produced into plate. These steel grades were developed to obtain resistance to stress corrosion cracking and pitting corrosion better than 18-8 stainless steel at a lower price than high nickel austenitic alloys. They are generally used only for heat exchanger tubular materials or sheets. Heat treatment does not cause them to harden, but in the annealed state they show higher strength than many austenitic stainless steels. The following table lists the major wrought ferritic steels in the order of increasing resistance to chloride pitting. Wire Mesh Machine,Tumbler Machine,Tumbler Sifting Machine Yongzhong Wiremesh Co., Ltd. , http://www.hbwires.com
Class F1 ferritic stainless steel Such stainless steels, such as E-BRITE26-1, have localized corrosion resistance similar to that of 316 stainless steel, but their resistance to stress corrosion cracking is much better than that of the latter. This good stress corrosion cracking property makes it useful for hot concentrated alkali solutions and chloride containing solutions.
Type F2 ferritic stainless Steel Tube This type of stainless steel tube, including SEA-CURE, is designed for local corrosion resistance to room temperature seawater and is widely used in power plant seawater cooled condensers. Due to their high chromium content and moderate levels of molybdenum and nickel, they are also highly resistant to strong organic acids and oxidative or moderately reducing inorganic acids. However, the nickel in these steels reduces the resistance to chloride stress corrosion cracking and increases the sensitivity to harmful secondary phases. All of these ferritic stainless steel pipes are resistant to stress corrosion cracking in the sodium chloride test solution, but due to their nickel content of 0.5% to 4.2%, they may not be resistant to stress corrosion cracking of the magnesium chloride test solution.
F3 ferritic stainless steel is similar to A6 high-performance austenitic stainless steel tube. The AL29-4-2 in this type is designed to achieve the highest level of ferritic stainless steel's overall performance. It has good resistance. Local corrosion and acid corrosion resistance.
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