Why Stainless? 150,000 Litre Tanks... 3CR12, an Excellent Material for Atmospheric Applications... Tersainox and its New Production Lines... Super-Duplex Stainless Steel... May 2011 Edition NВ° 55 English Why Stainless? The main reason for stainless steelвЂ™s existence is its resistance to corrosion. Chromium is the principal alloyed element and stainless steel contains at least 11%. Chromium is a reactive element, however the alloys that contain Chromium passivated, demonstrating an excellent resistance to many conditions. Stainless steel refers to a great number of alloys resistant to corrosion, with specific mechanical properties and the cost varies considerably. In our area, despite the fact that the demand for these materials has increased significantly, the domestic industry continues to cover almost 90% of its stainless steel need with barely two or three types of these alloys, the most common of which being AISI 304 and AISI 316. The stainless steel properties are significantly influenced by their chemical composition, which in turn determines these alloysвЂ™ micro-structural characteristics. At present, stainless steel can be generally classified in four main families: - Ferritic stainless steel Austenitic stainless steel Martensitic stainless steel Austenitic ferritic (Duplex) In addition to these, there are other new types of stainless steel such as hardenable ferritic- martensitic stainless steel. Page N. 1 Why Stainless? Ferritic Stainless Steel This type of alloys contains between 12% and 29% Cromium and very low quantities of Ni [Nickel] (2%). Its name is derived from its microstructure, entirely constituted of ferrite. This type of stainless steel is more economic due to its low content of Ni. However, the economical advantages derived from this are not able to fully utilise this value in these alloys, mainly due to the technological difficulties associated with the greater probability of provoking secondary phases (difficulty in fabricating products of great thickness and weldability problems). This aside, due to its good resistance to stress corrosion cracking (SCC), to corrosion pitting and crevice in media containing chloride, it may be selected in particular applications, as an alternative to austenitic stainless steel. Ferritic stainless steel is magnetic, has good ductility and is resistant to corrosion and oxidation at high temperatures. The stainless steel type AISI 430 is the most common of this group; it contains 17% Cr and is considered as a multipurpose alloy for applications where the corrosion resistance demands, especially in the welded joints, are not so important. The stainless steel type AISI444 (18% Cr 2% Mo) holds a better resistance to corrosion from pitting and crevice equivalent to austenitic stainless steel type AISI 316L. In recent years ferritic stainless steel has being developed, specifically designed for their use in the manufacture of sea water condensing units. Alloys for this type of application usually contain Cr > 26% and Mo > 3% and are known as super-ferritic stainless steel. Page N. 2 Why Stainless? Austenitic Stainless Steel This is the most popular group of the stainless steel family. It is made up of cold-rolled hardenable non-magnetic alloys (when cold-rolled it is possible that they may become slightly magnetic) but not for heat treatment. Its microstructure is fundamentally constituted of austenite grains. The presence of Ni in these steels allows the stabilisation of the austenitic phase while the only addition is that of Cr, which would produce a ferritic microstructure at room temperature. Austenitic stainless steel has an excellent resistance to corrosion, very good conformality and it is generally very easily welded (better than ferritic stainless steel). The stainless steel type AISI 304L (19% Cr вЂ“ 10% Ni) is the most represented of this alloy group. It has good resistance to atmospheric corrosion and is used to a large degree in the chemical, food and medical industries. When the service conditions demand greater resistance to pitting corrosion is used the stainless steel type AISI 316 is used (17% Cr вЂ“ 12% Ni вЂ“ 2% Mo) which is used mainly in industrial processes such as paper manufacture and the food industry. The AOD process allows one to obtain stainless steel with S (Sulphur) contents less than even 0.001%. This helped to reduce the problems of fragility under heat and effectively initiated the development of more and more alloyed stainless steel. Therefore new types of more resistant alloys such as the grade AISI 317 (18% Cr 13% Ni вЂ“ 3.5 Mo) and вЂњsuper austeniticвЂќ stainless steels with further additions of Mo and N were introduced. In this last group the alloy types 20% Cr вЂ“ 18$ Ni вЂ“ 6% Mo вЂ“ 0.2% N (Avesta TM 654 SMO), considered as one of the most manufactured commercial austenitic stainless steel to date, capable of competing in corrosions resistance with the majority of the Nickel-based super alloys. These new alloys are used in chemical processes with the presence of very aggressive media (high concentrations of chlorides and high temperatures). The typical applications are pulp mills, sea water piping systems, structural element constructions for offshore platforms, etc. Tersainox has earned national as well as international reputation in the handling of this family of noble materials: AISI 304L, AISI 316>, 3CR12, ACEROS DUPLES LDX 2101, SAF 2304, 2205, 254 SMP, 904-l, AL6 XN, HASTELLOY. We have an experienced group of experts who will be able to locate the type of stainless steel in the best way possible in order to find the solution for your needs. Patricio Campos Castro Mining and Industry Division Tersainox Group Inc. Page N. 3 150,000 Litre Tanks Tersainox S.A. manufactured 150,000 litre capacity tanks with great success in first quality steel, types 304-L and 316-L. This manufacture was completed in a minimum timeframe, meeting the demands and sanitary norms as well as the creation of these. The tanks were built in our plant and transported to the new clientвЂ™s plant; once in the plant heavy machinery was required such as cranes and others in order to install and anchor the tanks, a task that was carried out with great success and satisfaction from the client. Remarks from the commercial manager, Mr.: Eric Miranda Lagos Delay of the project was contemplated, given the demands of the tanks in terms of quality as well as the commitments that would be taken up with our new clients, the time allocated was not sufficient. To us this new plant had to meet the European quality standards; in other projects these were not met with Chilean manufacturers. After visiting Tersainox with German engineers, we made the decision to handover the manufacture of equipment to this company, being able to comply with the product manufacture requirements. Following various meetings with Tersainox executives we decided to commit to the project; a good decision, as we successfully installed the equipment in order to be able to process and thus fulfil our contracts. Remarks by the owner of the company. Eric Miranda Lagos Food Division Tersainox Group Inc. Page N. 4 3CR12, an Excellent Material for Atmospheric Applications The stainless steel type 3CR12 is an excellent material for more severe atmospheric applications. A study prepared by BG Callaghan (CISR Science and Technology, Materials Division), produced an essay on Atmospheric Corrosion in South Africa during a 20 year period in different atmospheric conditions and on different types of steel, which demonstrated the following results. 3CR12 is very corrosive resistant in marine and highly corrosive environments, when compared with galvanized steel which can last between one and five years and after the zinc is consumed the corrosion shall be the same as that which common carbon steel reveals. 3CR12 has a performance similar to that of aluminium in marine environments; with the coating application, it has proved very successful in highly corrosive environments. We know two examples of 3CR12 used in bridges in the south of Africa: The Millenium Bridge in Umshlanga Rocks in Natal , which is made from tubular sections, and pedestrian bridges along the south coast where reinforcement bars of 3CR12 were used. Cristian Lohse Sales Executive Tersainox Group Inc. Page N. 5 Tersainox and its New Production Lines Last year, in our constant determination to improve our production plant, the expansion of the external production area associated with workshops was undertaken and today we can show you the improvements made in this area: Reinforced concrete slabs with two external production lines plus their respective gates. In the attached photo you can appreciate that one of the concrete slab production lines is already being worked on, using the space and surface quality with the implementation of a new assembly line for road tankers. The other production line shall soon be in operation and its plans are already being programmed. Tersainox S.A. is proud to be growing and improving its production capacity for its current and future stainless steel projects. The problems and inconveniences we experience today in our daily work shall be replaced with the largest installed capacity in our plant that we offer you all. вЂњWhen you think stainless steel, think TersainoxвЂќ. Guillermo Rudolph Sales Engineer Tersainox Group Inc. Page N. 6 Super-Duplex Stainless Steel The first generation Duplex stainless steel was developed in Sweden more than 70 years ago for use in the paper industry. Duplex alloys were originally created to combat corrosion problems caused by chloride-bearing cooling waters and other aggressive chemical process fluids. Called Duplex because of its mixed microstructure with about equal proportions of ferrite and austenite, Duplex stainless steels are a family of grades, which range in corrosion performance depending on their alloy content. The term "Super-Duplex" was first used in the 1980's to denote highly alloyed, high-performance Duplex steel with a pitting resistance equivalent of >40 (based on Cr% + 3.3Mo% + 16N%). With its high level of chromium, Super-Duplex steel provides outstanding resistance to acids, acid chlorides, caustic solutions and other environments in the chemical/petrochemical, pulp and paper industries, often replacing 300 series stainless steel, high nickel super-austenitic steels and nickel-based alloys. Recently, the production of high-strength, corrosion resistant super-duplex coil has been implemented in the marine and chemical industries, architecture and mast riggings, wire lines, lifting and pulley equipment and well service strands. In fact, development of wire processing techniques has enabled the production of steel wires down to 1mm in diameter. Modern Duplex stainless steel can be divided into four groups: 1. Lean Duplex such as 2304, which contains no deliberate Mo addition; 2. 2205, the work-horse grade accounting for more than 80% of duplex usage; 3. 25 Cr duplex such as Alloy 255 and DP-3; 4. Super-Duplex; with 25-26 Cr and increased Mo and N compared with 25 Cr grades, including grades such as 2507, Zeron 100, UR 52N+, and DP-3W BENEFITS вЂў High strength, вЂў High resistance to pitting, crevice corrosion resistance. вЂў High resistance to stress corrosion cracking, corrosion fatigue and erosion, вЂў Excellent resistance to chloride stress-corrosion cracking вЂў High thermal conductivity вЂў Low coeп¬ѓcient of thermal expansion вЂў Good sulphide stress corrosion resistance, вЂў Low thermal expansion and higher heat conductivity than austenitic steels, вЂў Good workability and weldability, вЂў High energy absorption. APPLICATIONS вЂў Heat exchanger tubes and pipes for production and handling of gas and oil, вЂў Heat exchanger and pipes in desalination plants, вЂў Mechanical and structural components, вЂў Power industry FGD systems, вЂў Pipes in process industries handling solutions containing chlorides, вЂў Utility and industrial systems, rotors, fans, shafts and press rolls where the high corrosion fatigue strength can be utilized, вЂў Cargo tanks, vessels, piping and welding consumables for chemical tankers. вЂў High-strength, highly resistant wiring. Marcelo Salas Australia Tersainox Pty.Ltd Page N. 7