STAINLESS STEELS
How they “work”
Stainless steels are so called because their main characteristic is to be resistant to oxidation. Stainless steels also have other properties, such as refractoriness (resistance to high-temperatures), easy sanitization which allows their used in contact with food, the resistance to corrosive environments.
Stainlessness is guaranteed by the presence of chromium (minimum content of 10,50%) and by other chemical elements that, as well as conferring particular metallographic structures, improve the resistance to corrosion.
Types of stainless steels available at Gieffeacciai
Martensitic stainless steels
The 410 has good corrosion resistance in moderately corrosive environments, such as steam, fresh water, foodstuffs. It should not to be used in highly corrosive environments.
The 420 is the most widely used martensitic steel because, thanks to its carbon content, it is possible to achieve excellent mechanical values after quenching and tempering. The carbon content increases, going from 420A, to 420B up to 420C. They are used in pumps, moulds, tools and springs sector.
The 440C has a carbon content close to 1% and a chromium content higher than previous steels, which makes it usable, quenching and tempering, in bearings, diesel engines and surgical tools sector.
For those who require high machinability, the 430F is available, resulphurised steel and therefore suitable for chips that break easily during machining.
Precipitation hardened martensitic steels
Among the martensitic steels, the 630 can be found, also known as 17-4 PH, a precipitation hardened steel, mainly used in the oil and gas field, turbines and the marine sector.
Austenitic stainless steels
The most common one is the 304, also known in Italy as 18-10, used in a lot of sectors, among which domestic (cutlery, pots), automotive and industrial systems. There is also its low carbon version, the 304L that has a better corrosion resistance.
The improved machinability version of 304 is the 303, which can be found in standard or calcium-treated versions that further improve the machinability and the tool life.
In case a good resistance to chloride-rich environments is required, 316 can be used, even in the low-carbon version (316L) or in the titanium stabilized version (316Ti).
Nitronic 50 has a higher resistance to corrosion in the marine environment than 316, together with higher mechanical properties.
Heat-resistant austenic stainless steels
The 310 is a steel designed to be used in environments where heat resistance is required, such as furnaces, furnaces and heat exchangers.
Austenic-ferritic stainless steels
Also known as Duplex, these steels are characterized by excellent resistance to corrosion under stress and pitting and by high mechanical characteristics.
Gieffeacciai has three austenic-ferritic steel in its catalogue: F51, F53 and F55 with an increasing PREN (Pitting Resistance Equivalent Number) and consequently with a better pitting resistance.
