
To simplify the choice of stainless steel, we can divide them into:
The austenitic stainless steel or the AISI 300 series, represents the largest group of stainless steel types. This group is derived from 18/8 composition. 18 stands for 18% Cr (chromium) and 8 stands for 8% Ni (nickel). The material is non-magnetic, has good corrosion resistance, a high coefficient of expansion and is a poor conductor of heat and electricity. The mechanical strength is moderate, but increases strongly during cold working. The material then becomes weakly magnetic.
The most commonly used types in the AISI 300 series are: 304, 304L, 321, 316, 316L and 316Ti. In the material numbers these are the types: 1.4301, 1.4306, 1.4541, 1.4401, 1.4404 and 1.4571. Most of the products that HOLLIMEX has in stock fall under one of these types. The 316 types are generally somewhat more resistant to corrosion and are therefore more suitable for an acidic and/or maritime climate. The L and Ti types are better suited for welding.
Other types that fall under this are: 410 / 1.4006, 420 / 1.4021, 420 / 1.4028, 1.4034, 431 /1.4057, 430F / 1.4104, 440B / 1.4112, 1.4122, 303 / 1.4305, 1.4307, 1.4313, 1.4418, 316L / 1.4435, 329 / 1.4460, 630 / 1.4542. Want to know more?
This stainless steel type is reasonably corrosion resistant and is not magnetic in the soft annealed condition. If one wants to increase the hardness this can only be done by cold forming, the material then also becomes weakly magnetic. The material is slightly sensitive to the precipitation of carbides during welding. Suitable for equipment for which weldability, polishability and very good deep drawing properties and wear resistance are required.
Applications:
equipment and components for the food and beverage industry, equipment and components for the chemical industry, non-cutting surgical instruments and household appliances.
Variant of AISI 304 with a low carbon content. Mainly used for welding purposes, and especially if annealing treatment cannot follow afterwards. The service temperature may not exceed 425°C.
The heat treatment is limited to:
stress relieving annealing to relieve internal stresses soft annealing to obtain an improved structure, so that the material obtains optimum corrosion resistance and softness.
Applications:
equipment and components that come into contact with organic acids and fruit acids in the food, oil, fat and synthetic fibre industries.
This type of stainless steel is very corrosion resistant compared to other chrome-nickel steels and is non-magnetic in the soft annealed condition. Suitable for sulphuric, phosphoric and nitric acids.
At a processing temperature of up to approx. 300°C resistant to intercrystalline corrosion. At high temperatures a very good creep strength. Suitable for maritime climate.
Applications:
equipment and parts for the food and beverage industry, equipment and parts for the chemical and pharmaceutical industries, equipment and parts for the oil, fat and textile industries.
Variant of AISI 316 with a low carbon content. Mainly used for welding purposes
(see further under AISI 316 and 304L).
The addition of titanium makes this type of stainless steel resistant to intercrystalline corrosion, making it easy to weld. However, the addition of titanium means it cannot be polished to a high gloss.
Applications:
equipment and parts for the chemical industry equipment and parts for the textile and paint industry equipment and parts for the photo, rubber and synthetic resin industries.
The above stainless steel grades are all austenitic.
Nowadays, most semi-finished products, appendages and process components are made in the L variant supplied.
These are steel types that retain their good mechanical properties under both short and long-term loads and are also highly resistant to the effects of hot gases and combustion products at temperatures from approx. 550°C. The degree of resistance is highly dependent on the environment in which the steel is located. Some steel types can withstand temperatures up to approx. 1150°.
The resistance can vary greatly due to the presence of water vapour, sulphur or ash particles. The resistance to molten metals and salts is very limited.
The most commonly used types are: 314 / 1.4841 - 309 / 1.4828 and 310S / 1.4845.
Other types that fall under this are: 1.4713, 1.4742, 1.4876, 321 / 1.4878 and 1.4923.
These are corrosion-resistant steel types that are very resistant to chemically aggressive substances due to, among other things, their high content of nickel, chromium, molybdenum and copper.
The most commonly used grades are: 317LNM / 1.4439 - 904L / 1.4539 and UNS 31803 / 1.4462
Other types that also fall under this are: 1.4529, 1.4563 and 317L / 1.4438.
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