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STAINLESS STELL

Stainless steel was invented by Harry Brearly in 1912. He was investigating corrosion (rusting) of rifle barrels. As a result of his investigations, he developed a chrome alloy steel which was much more rust resistant than the steel which had been used until then.

Stainless steel is the general name of steels that are stainless. The main element is the chrome which consists the stainless characteristic, even nikel and molybdenum are used in production of the alloy to make the stainless characteristic better.

Alloys are obtained which have different features by changing chemical combinations in the stainless steels. Corrosion endurance can be raised by promoting chrome quantity or adding elements such as nickel and molybdenum.

Apart from these , positive effects can be obtained by adding copper, aliminium, titanium, silicon, niobium, nitrogen, sulfur and selenium. So, in this way, machine designers and makers can have an opportunity in order to choose the best stainless steel for different usages.

In the stainless steel, the most important alloy elements, as orderly, are chrome, nickel, molybdenum and manganese which are determined the inner structure.

STAINLESS STEEL
Stainless steels have 5 main groups:

  * Ferritic,
  * Martensitic,
  * Oustensitic,
  * Ferritic-Oustenitic (Dublex),
  * Allow that can be implemented settling of hardening.

This group has been made in acccordance with the internal structure of the material.The most common steels are Austenitic and  Ferritic steels and their usage has 95% quato among the all stainless steels.

Click to Stainless Steel to table. 

ADVANTAGES OF STAINLESS STEEL

  • Corrosion Resistance to Advanced
  • It can not be seen drastically decrease in these steels in terms of  mechanical resistance of the material and oxidation even the high heat.Some types of these steels have preserved its fullness and fragility even low heat
  • Almost all of steels can be shaped by dint of the processing of cutting,welding, hot and cold shaping and machining.
  • Almost all of the steels become rigid with cold shaping and as a consequence of increasing of resistance, reasonably decrease can be provided in terms of price and individual weight by dint of decreasing of material thickness during the designing.Also it is possible to get a resistance to the material by means of the heat treatment.
  • The stainless steels can be supplied as so many different quality of surfaces.Owing to the fact that the prospect, quality and maintenance of these surfaces are easy they can be protected for a long time
  • That stainless steels can be easy to clean provide them to use in the hospitals, kitchens, food and medicine industries commonly.
  • Because stainless steel are durable and easy materials in terms of maintenance, the produced material has a longevity and they are an economical materials.

GENERAL USAGE SCOPES
That stainless steels can be obtained in a variety of quality and features generalize their usage continuously in the present day. Today, they have been used as product range from jewelry to big industry enterprises. So many products,using in our everyday life, heve been made of stainless steel. Besides stainless steel can appear as a kitchen utensil, they can be shown itself as an art work,is wild about by us, while we are are looking round.This material can display itself almost all places in the chemistry enterprise it can be also seen as a kind of decorative material that covered skyscraper walls. Besides captured attention of us so many details of a shopping centers, stainless steels can be used for many industrial products that provide our safety and convenience in the unknown pleces by us commonly.

Where stainless steel are used and which rates determine a kind of fact that has an informative sign directly about country economy. That its usage rate exceeds the limits is seen in the countries that have faltering economy generally.That its usage is improved in terms of energy, production of machine and transportation areas show the economic power of the country. In the below, graphic gives information about proportional dispersion of the stainless steel in the world in 2002

Ferritic Stainless Steels
They have low-carbon and contain 12-18 % chrome

Specifications:
  * They have medium and good quantity corrosion resistance and corrosion resistance becomes better if chrome quantity is raising
  * Their resistance can not be developed by thermal process and they can be used as only tempered.
  * They are magnetic.
  * Their welding ability is low.
  * They can not be shaped easily like austenitic steels.

Usage Scopes:  Kitchen utensils, decorative practices, automobile under frame pieces, exhaust equipment, hot water tanks

Martensitic Stainless Steels
That stainless steels have chrome more than 0,1 % have austenitic internal structure in high temperature. The austenitizing temperature is between 950-1050 degree celcius in accordance wth the type of stainless steels.If the water is given such kind of steel, martensitic internal structure can be obtained.Getting such kind of mechanical resistance and high hardness can improve with the carbon percentage

Martensitic stainless steels are presented to the market in accordance with the tempered or improved.The products that are bought as tempered subjected to the improved processing (give water + tempering ) after shaping. Different combinations can be obtained by dint of changing the tempering temperature. In order to get the best corrosion resistance, it is important to do the recommended thermal process temperature

Başlıca Özellikleri
  * They have medium corrosion resistance
  * Thermal process can be implemented,thus high endurance and hardness can be gotton
  * Welding ability is low.
  * They are magnetic.

Usage Scopes: Knives, operation equipment, mills, bolts

Austenitic Stainless Steels
If there is enough nickel in stainless steel, its internal structure is austenitic even room temperature. Combination of the Austenitic Stainless Steels have 18 % chrome and 8% steel. These stainless steels present an agreeable combination in terms of shaping, mechanical features, corrosion resistance. Their ductility, gult and formulation abilities are perfect even low temperature. Due to fact that they are not magnetic, hardening thermal process can not be implemented because austenitic internal structure can not show a change and their mechanical resistance can be raised only by cold shaping

Austenitic stainless steels have 70 % quato in total stainless steel production and among them the most common type is 304 quality

Specifications :
  * They have perfect corrosion resistance.
  * Welding ability is great.
  * They are easy to shaped because of ductility.
  * They are hygienic and maintenance is easy.
  * They have good mechanical resistance at high temperature.
  * Their mechanical resistance absolute at low temperature.
  * They are not magnetic. ( as tempered )

Usage Scopes : Machine and production practices, lifts, covering building exterior, architectural practices, food process equipment, kitchen utensils, chemistry enterprices ano equipment, computer and keyboard bows, kitchen outfits

Austenitic- Ferritic (Dublex) Stainless Steels
They contain high percentage of chrome (18-28%) and average nickel (4,5-8 % ). The maximum nickel quantity is 8% but it s not enough for austenitic internal structure. Because phase is formed by ferritic and austenitic internal structure, they are called as duslex. Most of them contain 2,5-4 % molybdenum. These provide not only good strenght but also well ductility. Also they have fatigue strenght even in the corrosive environment.Their welding is easy to do if it is implemented in accordance with the recommended. They have been used generally chemical apparatus production, sewage treatment plants and technology of ship or off-shore

Specifications :
  * They have high endurance against streching corrosion..
  * They show much more corrosive strenght in the environment not having chlor-iodine.
  * They have higher resistance than ferritic and austenitic steels.
  * There is good welding ability and shaping out.

Usage scopes: Sea and salt water environment, especially an average temperature, temperature modifier, petrochemical enterprises.

Alloys that can be implemented settling of hardening ( ageing):
Their internal structure can be austenitic, half-austenitic or martensitic. In order to perform settling, cold shaping may be required sometimes. So as to settling, the alloying is performed with aliminium, titanium, niobium and copper elements.Thus, stainless steels that their resistance raised to 1700 MPa can be obtained. They are solding in the market as tempered. Therefore, material is soft and production process can be implemented and then it can be hardened with one- stage low temperature.

Specifications:
  * There is an average and good degree corrosion resistance
  * They show a hyper mechanical resistance.
  * They have welding ability.
  * They are magnetic.

Usage Scopes: Pump and valve shafts




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