Materials Selection

Corrosion of Embedded Ferrous Metals in Woods

Timber is the most widely utilised natural materials in human history. It is a renewable material and readily available. Ferrous metal fasteners and fixtures are often used in the timber structure. They are generally reliable and maintenance free.  However, the pre-mature corrosion failures are identified in the history [1].  Field experience and test even suggested higher corrosion risk for outdoor applications [2]. If not attending carefully, it will lead to serious consequence.  Corrosion scientists also believe that wood provides a corrosive environment through permeable structure acting as an electrolyte sponge.  Recent research is not only focusing on understanding the corrosion…
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Metal Dusting: recent progress and industrial experience

The metal dusting is one of major failure mechanisms of equipment in producing process of hydrogen, ammonia, and syngas, as well as methanol reforming.  Although it has been recognized for the decades, there are still controversies in its mechanism.  With the recent development in metal dusting research, industries are having better understanding and may develop practical approaches to combat this type of failure. In this report, the recent research of metal dusting mechanism is summarized. It is reasonable to group these mechanisms in 3 types per Szakálos’ proposal: Type 1: decomposition of metastable carbides (e.g. cementite), Type 2: decomposition of…
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Corrosion under Polluted Atmospheric Environment

The atmospheric corrosion is probably the most common forms corrosion in daily life. The corrosion rate of steel is very much influenced by atmospheric environment. Under heavily polluted atmospheric environment, the corrosion is much severer than it in unpolluted environment. The factors of significance in atmospheric corrosion are time of wetness, rain, fog, dew are all contributing to the wetness. Temperature, particulate matters, wind direction, salt deposition and presence of pollutants etc are of great importance in atmospheric corrosion process. In an urban area and heavily industrial polluted zone, it has been proven both gaseous and solid forms of pollutants…
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Corrosion of ASTM 304 Grade Stainless Steel for Drinking Water Service

Grade 304  Stainless Steel Grade 304 is the standard “18/8” austenitic chromium-nickel stainless steel. It is the most versatile and most widely used stainless steel, available in the widest range of products, forms and finishes. It has excellent forming and welding characteristics. The austenitic structure also gives these grades excellent toughness, even down to cryogenic temperatures. 304 and its variant are general purpose stainless steel grade with good atmospheric corrosion resistance and many corrosive media. It subjects to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 60°C.  Considered resistant to pitting corrosion in…
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Intergranular corrosion for Stainless Steel

Intergranular corrosion for Stainless Steel Austenitic Stainless Steel For austenitic stainless steel, the cause of intergranular corrosion is precipitation of chromium carbides. At temperature above 1035oC, chromium carbides are completely dissolved in austenitic stainless steel. However, the steels are slowly cooled to 425~815oC, chromium carbides are precipitate at grain boundary. This causes the depletion of chromium content in the matrices. The depleted zone is more susceptible to corrosion, which is termed as sensitization. This leads to integranular corrosion of austenitic stainless steel.  The sensitization can be catalysed with cyanide, thiosulfate ions. Heat treatment with fast cooling below 425oC can prevent…
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