Because of the strong activity of aluminum, it is not easy to be reduced, so it was found late. 1800 Italian physicist volts create battery after, 1808 to 1810 years British chemist David and Swedish chemist Betsy Rius Du had tried to using current from aluminum vanadium shows C content), such as 1Cr18Ni9 thousands of (0.1%), rust C is equal to or less than 0.08% such as 0Cr18Ni9, super low carbon C is less than or equal to 0.03% as 0Cr17Ni13Mo international stainless steel marking method of American Iron and Steel Institute is the three digit to mark all standard grade stainless steel forging. Among them: the austenitic stainless steel with 200 and 300 series of digital signs, the ferrite and martensitic stainless steel with 400 series of digital representation. For example, some of the more common austenitic stainless steel is to 201, 304, 316 and 310 as markers, 3 iron prime stainless steel body is to 430 and 446 marked and martensitic stainless steel is to 410, 420 and 440C for labeling, dual phase (austenite - ferrite), stainless steel, precipitation hardening stainless steel and iron content of less than 50% of the high alloy is usually uses a proprietary name or trademark names. In contrast to the physical properties of stainless steel and carbon steel, the density of carbon steel is slightly higher than that of ferrite and martensitic stainless steel. 3) low thermal conductivity, about carbon steel 1/3. Stainless steel mechanical property regardless of stainless steel plate or heat resisting steel plate, the comprehensive properties of austenitic steel is best, both sufficient strength, and has excellent plasticity and hardness is not high, one of the reason of which is that they have been widely used. Austenitic stainless steel is similar to the vast majority of other metal materials, and its tensile strength, yield strength and hardness increase with the decrease of temperature, while the plasticity decreases with the decreasing of temperature. Its tensile strength is more uniform in the temperature range of 15~80 C. More importantly, with the decrease of temperature, the impact toughness decreases slowly, and there is no brittle transition temperature. Therefore, the stainless steel can maintain sufficient plasticity and toughness at low temperature. SUS304L: the basic austenitic steels, the most widely used; corrosion resistance and excellent heat resistance, low temperature strength and excellent mechanical properties. The single-phase austenite, no heat treatment hardening (non magnetic, temperature -196--800 DEG C). SUS304Cu: to 17Cr-7Ni-2Cu as the basic composition of austenitic stainless steel; forming of excellent, especially good drawing and anti ageing crack - resistant corrosion and 304. SUS316: corrosion resistance and high temperature strength is particularly good, can be used in harsh conditions, the work hardening of the good, no magnetism. For sea water equipment, chemicals, dyes, paper, oxalic acid, fertilizer production equipment, photographic, food industry, coastal facilities SUS316L: steel adding mo (2-3%), therefore the corrosion resistance and high temperature strength, excellent; SUS316L carbon content than SUS316 low. Therefore, anti intergranular corrosion than SUS316 excellent; high-temperature creep strength. Can be used in harsh conditions, the work hardening of the good, no magnetism. For sea water equipment, chemicals, dyes, paper, oxalic acid, fertilizer production equipment, photographic, food industry, coastal facilities SUS321: in 304 steel adding Ti, therefore the anti intergranular corrosion excellent; high temperature strength and high temperature anti - oxidation excellent; high cost, processing than 304. Heat resistant materials, vehicles, vehicle exhaust pipe, boiler cover, pipeline, chemical device, a heat exchanger. Surface processing level, characteristics and uses of the original surface: No.1 after hot rolling impose surface heat treatment and pickling treatment. Generally used for cold rolled materials, industrial tanks, chemical industry devices, thickness by 2.0MM-8.0MM. Blunt surface: NO.2D cold rolling after heat treatment, pickling, the material is soft, the surface is silver white luster, for deep stamping processing, such as automotive components, water pipes, etc.. Matt: after heat treatment and pickling NO.2B after cold rolling, then finishing processing to make the surface for the moderate bright. Because the surface is smooth, easy to re grinding, make the surface more bright, use a wide range, such as tableware, building materials, etc.. After surface treatment with improved mechanical properties, almost all uses are met. NO.3 100-120 sand abrasive belt grinding products. Has a better gloss, with a discontinuous coarse grain. For internal and external decoration materials, electrical appliances and kitchen equipment, etc.. Fine sand: NO.4 with a particle size of 150-180 grinding belt grinding out of the product. Has a better gloss, with a discontinuous rough lines, stripes than NO.3 fine. Inner and external decoration materials, electrical appliances, kitchen equipment and food equipment etc.. #320 with 320 grinding belt grinding out of the product. Has a better gloss, with a discontinuous rough lines, stripes than NO.4 fine. Inner and external decoration materials, electrical appliances, kitchen equipment and food equipment etc.. Fuzz face HAIRLINE:HL No.4 by the appropriate granularity of abrasive belt polishing continuous grinding generated grinding pattern model (subdivision 150-320 number). Mainly used in building decoration, elevator, building doors, panels, etc.. Bright surface: BA after cold rolling to impose bright annealing, and through the formation of products. Excellent surface gloss, has a high reflectivity. Like the surface of a mirror. Used for household electrical appliances, mirrors, kitchen equipment, decoration materials, etc.. The types of corrosion resistance of stainless steel and the definition of a kind of stainless steel can have good corrosion resistance in many media, but in another medium, it may be due to low chemical stability and corrosion. So, it is not possible for a stainless steel to all media corrosion. In many industrial applications, corrosion resistance of stainless steel can meet the people. The root of chromium rich oxide film (passivation film formation). This kind of stainless steel and corrosion resistance