Fyrtornet, Stockholm Material composition The table below shows the material composition of Marutex. It is manufactured from modified stainless martensitic steel, which gives it its great strength. The addition of molybdenum increases corrosion resi- stance. Material analysis Marutex in % Chromium Molybdenum Copper Silicon Manganese Nickel Carbon Phosphorous Sulphur 13,0 - 14,5 1,8 - 2,2 0,4 - 0,6 0,4 - 0,6 0,4 - 0,6 0,4 - 0,6 0,20 - 0,30 0,03 max 0,02 max There’s a diffrence between stainless and stainless What is stainless steel? Stainless steel is a general term referring to a large number of qualities in which the most important alloying materi- al is chromium. According to European Standard SS-EN 10088-1:2005, steel containing at least 10.5% chromium is defined as stainless steel. The European standard is also used as a Swedish stan- dard. The carbon content must be restricted when cor- rosion resistance is important. Chromium is a primary al- loying material. Chromium, which is not bound to carbon, determines corrosion resistance. In order to additionally improve resistance, other alloying materials, such as nickel and molybdenum, are also added. The correct surface? In order to achieve satisfactory corrosion resistance, the surface must be free of all oxides. Oxides form during heat working or heat treatment of the product. The oxide can be removed chemically through pickling, and/or mechanically, through grinding and polishing. The cleaner the surface is, the better the corrosion resistance will be. The correct alloy? The choice of a steel alloy depends on the properties the product is to have, and on what is most important for its function. The corrosion resistance in the environment where the final product is to be used is naturally the most important property. However, other properties, such as mechanical strength and hardness, can also be important. Generally, a higher content of the alloying materials chro- mium, nickel and molybdenum provide better corrosion resistance. Magnetism? Certain types of stainless steel are magnetisable. What is most important is the microstructure of the steel and how they are tempered and heat-treated. Literature references: • Swedish standard SS-EN 10088-1:2005 • SMS Handbook no 4, Rostfria stål (Stainless steel types), edition 6, 2000• • Karlebo handbook edition 15, 2000 3
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