Stainless Steel Pipe and Stainless Steel Tube Physical Properties

This stainless steel group, also known as the 300 series, accounts for about 60% of the total stainless steel production. They contain nickel and manganese to stabilize from low temperatures to melting temperatures. A maximum of 0.15% carbon and a minimum of 16% chromium combination forms the austenitic structure.

The best known type is 304 (1.4301) and 316L (1.4404) quality stainless steels. 304 quality contains 18-20% chromium, 8-10% nickel and 316L quality contains 16-18% chromium, 10-14% nickel and 2-3% Molybdenum.

Austenitic stainless steels cannot be heat treated and are non-magnetic. They can be hardened by rolling and have very high corrosion resistance, very good machining and welding capabilities.

Ferritic stainless steels generally do not contain nickel. It is a stainless steel group that contains alloy elements such as high incidence of chromium element (between 10.5% and 30%), molybdenum and titanium vanadium which makes the ferritic structure stable. The high incidence of chromium content they contain provides high corrosion resistance.

Unlike austenitics, the ferritic group is magnetic and cannot be heat treated since low carbon content. It can be heat treated only by annealing process.

Basic alloying elements are: 12% to 15% chromium, 0.2% to 1.0% molybdenum and 0.1% to 1.2% carbon. They do not contain nickel except for a few martensitic grades. Martensitic stainless steels are magnetic. Containing high incidence of carbon content increases hardness and strength while reducing toughness and ductility. After tempering or tempering heat treatment, the most suitable corrosion resistance is achieved by stress relief. Corrosion resistance is lower than ferritic and austenitic grades. Machinability properties are high. Martensitic steels can be applied very successfully especially in areas where strength and resistance to mechanical wear are required together with corrosion resistance. Also it is used as tool steel.

Duplex stainless steels have higher strength and corrosion resistance than austenitic stainless steels. Duplex grades are more resistant than austenitics due to their high content of chromium, which is between 19-28%, molybdenum up to 5% and nickel contents which are lower than austenitics. The temperature of the system to be used in product selection in this group is important. They are very brittle at low and high temperatures.

The most important limitation of duplex stainless steels is their brittleness at high and very low temperatures. The best known duplex stainless steel grade is 2205 grade.

Precipitation hardened stainless steels, also called aging hardened stainless steels are a type of stainless steel that mainly contains chromium and nickel and combines the properties of both martensitic and austenitic grades in a suitable manner.

Like martensitic stainless steels, they can gain high strength by heat treatment and they have corrosion resistance like austenitic grades. Hardening is achieved by the addition of one or more alloying elements such as copper, aluminum, titanium, niobium and molybdenum. The most commonly known quality in this group is 17-4 PH. This quality is also known as 630.
This grade that takes its name from content of 17% chromium and 4% nickel, also includes 4% copper and 0.3% niobium. (Superferritics  442  and  446  grades)