The main alloying elements of these steels are Chromium, Nickel, Manganese and Molybdenum. Nitrogen strongly increases the yield strength. Austenitic steel is often used where particularly high corrosion resistance is required, e.g. in the oil, gas and chemical industries, in sanitary and waste water technology, in the food industry and medical technology, but also in shipbuilding.
Austenitic stainless steels are essentially non-magnetic, have a medium yield strength, high work hardening tendency, high tensile strength, good ductility and excellent toughness even at low temperatures, are easy to weld and can be easily fabricated into complex shapes.
The most important alloying elements of such steels are Cr, Ni, Mn, Mo, C, N. The austenitic, face-centred cubic solid solution structure is achieved by a special balance of the alloying elements. Cr, Mo and others act as ferrite-stabilising elements in this context. Ni, Mn, C, N stabilise the austenitic solid solution. As a rule, a completely austenitic microstructure is aimed for in high-performance steels (super austenites); a small proportion of ferrite can occur in standard steels. This ferrite content makes these grades slightly ferromagnetic.
The corrosion resistance is essentially determined by the Cr and Mo content; the resistance to pitting and crevice corrosion is determined by the pitting corrosion equivalent PREN = %C+3.3%Mo + (16 -30)%N.
The resistance to intergranular corrosion is determined by the free Cr content, i.e. the Cr content not bound in the form of Cr carbides.
Standard steels with Ni contents of 10 to 15% Ni are particularly susceptible to stress corrosion cracking.
Austenitic high-performance steels are designed to be particularly resistant to corrosion under aggressive conditions, e.g. in strong acids, alkalis and chloride-containing media such as brackish water, seawater and brine. These types of steel tend to exhibit higher strength and greater resistance to stress corrosion cracking.
The mechanical strength in the steel group is determined by the alloy content, in particular the N content.
Austenitic Cr-Mn-Ni-Mo-N steels form a subgroup of this steel category. They have a higher initial strength and a more pronounced tendency to work hardening and are often considered a more economical alternative to Cr-Ni-Mo steels.
Austenitic steel is frequently used in the chemical industry, construction, waste water technology, sanitary engineering and the food industry, as well as in shipbuilding and medical technology. Good weldability plays an important role here.
In addition to corrosion resistance, easy cleaning after use also plays a major role in the decision in favour of these materials.
BÖHLER A220 is a low carbon, chromium-nickel-and molybdenum steel. Structure homogeneous, stable austenite. Weldable with analogous filler metal giving fully austenitic deposit. Resistant to intergranular corrosion in the temperature range up to 400°C. Does not require post-weld heat treatment. Resistance to acids having a reducing effect, like diluted sulphuric acid and hydrochloric acid is good. The steel is not susceptible to pitting, crevice and stress corrosion cracking in media containing chloride ions and possesses excellent resistance to the attack of urea. For optimum resistance, surfaces should be pickled. Cold forming properties are good. The steel is capable of taking a mirror finish. Components for urea plants, pump heads, valve stems, condensers, reactors, strippers, scrubbers. Equipment and parts in the dyeing industry, textile, paper and leather, chemical, pharmaceutical and synthetic fibre industries.
Read MoreBÖHLER A220SC is a low carbon, chromium nickel and molybdenum steel. Structure homogeneous, stable austenite. Weldable with analogous filler metal giving fully austenitic deposit. Resistant to intergranular corrosion in the temperature range up to 750°F (400°C). Resistance to acids having a reducing effect, like diluted sulphuric acid and hydrochloric acid is good. The steel is not susceptible to pitting, crevice and stress corrosion cracking in media containing chloride ions and possesses excellent resistance to the attack of urea and biocompatibility. Cold forming properties are good. The steel is capable of taking a mirror finish. The steel is produced as a remelt grade and thus meets the usual requirements for steel purity as specified for implant material.
Read MoreBÖHLER A224 is a stainless austenitic Cr-Ni-Mo steel with low carbon content. Resistant to intergranular corrosion up to 750°F (400°C). Heat treatment after welding not required. Good resistance to reducing acids, such as diluted sulfuric and hydrochloric acid, and to localized corrosion attack in media containing chlorine ions. Required surface finish pickled or polished. Very good cold formability, highly polishable.
Read MoreBÖHLER A405 is a stainless austenitic Cr-Ni-Mo steel with nitrogen content and extremely low carbon content. Resistant to intergranular corrosion up to 400°C. Heat treatment after welding is not required. Required surface finish: pickled. Very good cold formability. Very good polishability. The chemical composition has been optimised for specific use in urea systems. It is a modified austenitic stainless steel 310L with low carbon and silicon content and nitrogen addition to stabilise and strengthen the austenitic phase. The alloy has been specially developed for improved corrosion resistance properties in urea carbonate environments. The grade is also suitable for wet corrosive environments due to its high chromium, molybdenum and nitrogen content (PREN > 33). For components with the highest resistance requirements to boiling, concentrated nitric acid and solutions with a high chloride content at high temperatures, as well as for highly stressed systems in the urea industry, e.g. urea separators or complementary products (pipes, fittings, etc.).
Read MoreA506 is an austenitic stainless Cr-Ni-Mo-steel with sulfur addition for improved machinability, ideal for the production of drilled and milled screenplates and –drums for the pulp and paper industry and for food processing industry.
Read MoreAustenitic chromium-nickel-silicon steel with extra low carbon content. High corrosion resistance against highly concentrated nitric acid (80 – 99,5%) or nitric acid with additions of strong oxidiser. Resistant to intergranular corrosion up to 350 °C. Components in the chemical industry, e.g. heat exchanger, columns and acid refrigerators, Application temperature: -50°C up to 350°C, for transport and storage tanks max. 200°C.
Read MoreAustenitic chromium-nickel-silicon steel with extra low carbon content. High corrosion resistance against highly concentrated nitric acid (80 – 99,5%) or nitric acid with additions of strong oxidiser. Resistant to intergranular attack up to 350 °C. Components in the chemical industry, e.g. heat exchanger, columns, acid refrigerators, transport and storage tanks. Application temperature: -50°C up to 350°C.
Read MoreAustenitic chromium-nickel. Silicon steel with excellent corrosion resistance in sulfuric acid and nitric acid. Components in the chemical industry and fertilizer plants.
Read MoreAustenitic chromium-nickel stainless steel with excellent corrosion resistance in boiling nitric acid (concentration up to 80%). Fertiliser plants and production units for nitric acid, as well as for the reprocessing of nuclear fuel.
Read MoreBÖHLER A965SA is an austenitic stainless steel alloy with 6% molybdenum and nitrogen. It has very high resistance to crevice and surface corrosion and was specially developed for the requirements of the chemical industry, the pulp and paper industry and the oil/gas industry. Due to its PREN value of over 40, the material is particularly resistant to seawater and is therefore often used in offshore technology. Furthermore, BÖHLER A965SA is resistant to intergranular corrosion up to 400°C. The required surface finish is pickled, scale-free heat treated or machined. For applications in highly corrosive environments due to chemically aggressive media, e.g. for equipment and installations cooled with seawater and parts for offshore installations. In the chemical industry, where resistance to attack by pure acids as well as chloride ion-containing acids (especially sulphuric acid), organic acids and mixed acids in the higher pressure and temperature range is required. The increased resistance to crevice corrosion also allows the use where incrustations must be expected and / or where the formation of crevices cannot be avoided by constructive measures.
Read MoreBöhler A970 is a stainless austenitic CrNiMoCu steel with excellent resistance to pitting, crevice and stress corrosion cracking. It is also resistant to intergranular corrosion up to 400°C. Required surface finish pickled, scale-free heat treated or machined. For components subjected to highly corrosive conditions, e.g. in seawater-cooled plants and in offshore applications. In areas of the chemical industry where, at higher pressures and temperatures, there is exposure to pure acids as well as acids containing chlorine ions (especially sulphuric acid), organic acids and acid mixtures. Due to the increased resistance to crevice corrosion, it can also be used wherever the formation of deposits is to be expected or where crevices cannot be prevented by constructive measures.
Read MoreBÖHLER P501 is a highly corrosion-resistant, nitrogen-strengthened Cr-Ni-Mo-N steel that is characterised by its resistance to corrosion in seawater and very good resistance to intergranular corrosion and stress corrosion cracking. Due to the alloy design, the yield strength is significantly higher than that of a comparable Cr-Ni-Mo stainless steels and a stable austenitic microstructure is achieved, so that the steel remains non-magnetisable even after cold forming and has the lowest magnetic permeability. In addition to its original application as a hull and structure for submarines, BÖHLER P501 is also used for magnetic shielding and components in the oil and gas industry, for example.
Read MoreBÖHLER P511 is a weldable, non-magnetic, austenitic steel with resistance to seawater and intergranular corrosion. This austenitic, stainless Cr-Ni-Mn-Mo-N steel has higher corrosion resistance than Cr-Ni-Mo grades 316, 316L, 317 and 317L and approximately twice the yield strength at room temperature. In addition, BÖHLER P511 has very good mechanical properties at both high and low temperatures. Unlike many austenitic stainless steels, it does not become magnetic when cold-formed or cooled to sub-zero temperatures. Thanks to its excellent notched impact strength at -196 °C (-320 °F), BÖHLER P511 is particularly suitable for low-temperature applications. Typical applications are found in the oil and gas, chemical, fertilizer, paper, textile, food and marine industries for components requiring a combination of excellent corrosion resistance and high strength, e.g. pumps, valves and fittings, fasteners, cables, chains, ship fittings, boat and valve shafts, heat exchanger parts and springs.
Read MoreBÖHLER P513 is a weldable, non-magnetic, austenitic stainless steel with resistance to seawater and intercrystalline corrosion. It offers the best abrasion resistance of all stainless steels. The corrosion resistance of BÖHLER P513 is better than that of conventional austenitic Cr-Ni steels (type 304), and even better than Cr-Ni-Mo steel (type 316) under standard test conditions against chloride pitting, stress corrosion cracking and crevice corrosion. BÖHLER P513 is an alloy with a high silicon and manganese content and added nitrogen, which also works well at high temperatures around 1800 ºF. Silicon and manganese prevent wear and scuffing even in the annealed condition. Higher strengths can be achieved by cold forming, but this does not significantly improve abrasion resistance. BÖHLER P513 is used in the aerospace, food and pharmaceutical, oilfield, petrochemical, surgical and chemical industries, e.g. for valve stems and valve seats, fastening systems, shielding, chain drive systems, pins, bushings and roller bearings, wear rings and pistons in pumps.
Read More