Background.
The first cast of duplex was made at Avesta in Sweden in 1930 when the idea of duplex stainless steels were subjected to discuss within industries. During last 30 years the duplex steels have been remarkably evolved and used in a significant way. The evolution in steel making techniques affected mainly to this take off.
Best services for writing your paper according to Trustpilot
Duplex stainless steels is a combination of many of the beneficial properties of ferritic and austenitic steels. First duplex steel grades had a great performance characteristics as well as limitations. The metallurgical processes at that time were not suitable for producing grades with the right austenite-ferrite balance. These early duplex steels were also high in carbon content because of the unavailability of efficient decarburization techniques. Because of these limitations the products using this materials were limited to specific applications. (Alvares-Armas, 2008)
Advancement of processing techniques in late 1960s and early 1970s led to the fabrication of modern duplex steels. Introduction of vacuum and argon oxygen decarburization (VOD and AOD) was the main factor that led to this massive development in duplex steels during this period. By the advancement of these techniques it was possible to achieve steels with low carbon content mixing with high nitrogen and chromium contents in balance with austenite and ferrite. This eliminated lot of shortcomings in old duplex steels. The alloy content provided a resistant to corrosion while duplex microstructure contributed to prevent chloride stress cracking under severe conditions. And these duplex steels possessed good weld ability also.Modern duplexes were used for offshore and near shore industries where conditions are severe and …
… cutting which uses a flame-fired torch using oxygen and propane in conjunction with iron powder is also used to cut steel. This method is clean and fast. Plasma jet cutting, is another method that uses an ionized gas column in conjunction with an electric arc through a small orifice. The gas produces extremely high temperatures to melt the metal. (Chater, 2010)Finishing
Finally the surface is finished to the required standard by using several methods.Finish type MethodDull finish Hot rolling, annealing, and descalingBright finish First hot rolling and then cold rolling on polished rollsHighly reflective finish Cold rolling in combination with annealing in a controlled atmosphere furnace, by grinding with abrasives, or by buffing a finely ground surfaceMirror finish Polishing with progressively finer abrasives, followed by extensive buffing
