Stainless steel is an alloy of iron-chromium-carbon with a minimum of 10.5% chromium content by weight Chromium creates a tiny layer (10-100 nm) of chromium trioxide (Cr2O3), which protects the metal substrate from oxidation and corrosion. In addition to chromium, stainless steel may contain other alloying elements such as nickel, molybdenum, manganese, etc. Stainless steel produced in electric furnaces with remelting scrap (scrap), ferroalloys (eg ferrochrome, ferronickel, etc.) and other metallic additions. They are widely used in many applications requiring corrosion resistance for economic reasons (eg chemical industry), for aesthetic reasons (eg architecture) or for health reasons (eg, utensils). Compared to common steels, stainless steels, in addition to much higher corrosion resistance, and additionally exhibit a higher mechanical strength. However, it is harder than common steel and therefore more unprocessable. Stainless steels also have low thermal conductivity compared to ordinary steels.
The most common stainless steel is 18/8 (18% Cr, 8% Ni) and 18/10 (18% Cr, 10% Ni)
The steel (commonly steel) is an iron-carbon alloy containing less than 2.06 wt% carbon less than 1.0% manganese, and small percentages of silicon, phosphorus, sulfur and oxygen. The alloyed steels, such as stainless steel, the tool steel, etc., constitute a special category of steels containing higher percentages of other metals. It is the most widely used construction material after concrete and wood. It is used everywhere: from architecture and shipbuilding to the manufacture of surgical instruments. The steel is one of the most important industrial materials and steel (steel plants) belong to the "heavy industries". In earlier times, industrial production in a country evaluated by the production of steel. One of the three European Communities established in 1957 was the European Coal and Steel Community.
Aluminum or aluminum (Aluminium) is the chemical element symbol Al and atomic number 13. It is a Argyrolefkes metal element belonging to group IIIA (13) of the periodic system with boron. It is the most abundant metal in the Earth's crust and overall the third (3rd) most abundant chemical element in total on our planet after oxygen and silicon. When weight is about 8% of the crust. However it is highly reactive chemical that is found in nature as a free metal. Conversely, it is bonded to more than 270 different minerals . The main source for the manufacture of the metal is bauxite. The metal aluminum has (seemingly) great ability to resist corrosion. This essentially is because the exposure of the metal in the atmosphere forms briefly one minute surface, invisible, layer of oxide, which prevents deeper erosion (phenomenon of passivation). Also, because of its relatively low density and large capacity to create a wide variety of alloys, became a strategic metal for the aerospace industry (and not only) industry. It is also extremely useful in the chemical industry both as such as a catalyst, and in the form of various associations.