AISI 439 Steel

Stainless titanium stabilized nickel-free ferritic steel grade AISI 439 is an improved analogue of 08Cr17T steel. According to GOST 5632-72 AISI 439 has corrosion resistance in most oxidizing environments (from fresh water to boiling acids), balanced chemical composition, which provides resistance to intergranular corrosion and high corrosion resistance. Analogues: AISI 439 / 430Ti (USA); GOST 08x17t; EN 1.4510 (Europe); DIN X3CrTi17 (Germany).

Chemical composition.

Advantages

The presence in the steel AISI 439 of additives Al and Ti plus the low carbon content gives it high plastic and strength properties similar to those of nickel-containing steel AISI 304. AISI 439 steel is characterized by high structural stability under welding and extreme heat. It also combines good plasticity (required for punching and perforation of holes) and high strength. This grade, according to GOST 5632-72 is recommended as a substitute for steel 12X18H9T or ...10T. Stabilization of the structure with titanium and the minimum percentage of carbon provides excellent weldability, lack of tendency to intergranular corrosion. Active carbide formation starts to occur only at temperatures above 1000 °C.

Corrosion resistance in most environments can be compared with the resistance of austenitic steels AISI 304, 12X18H10T. Grade AISI 439 is resistant to corrosion in water, in the air (including the oxidation at high temperatures), as well as in solutions of most alkalis and many organic acids, carbon-containing organic compounds (including animal and vegetable origin), in a solution of nitric acid.

Additional advantages of the steel is that, in comparison with austenitic nickel-containing grades, this steel is insensitive to intergranular corrosion cracking in the temperature range of 500-800°C and is much less sensitive under load to chloride cracking. Under load, resistance to chloride cracking is ~ 350 MPa, while for 08Cr18Ni10T steel (and other nickel austenitic steels) this value is not higher than 150 MPa.

The table below shows comparative properties of AISI 439 and 12X18N10T steels.

Relevance

Unlike austenitic nickel-containing steels, ferritic stainless alloys are resistant to sulphur-containing media, thanks to which pipes made of this steel can be used in systems for transferring oil, gas and derivative oil products in technological installations for gas or oil refining.

AISI 439 steel is resistant to gaseous media resulting from fuel combustion. These media contain products of incomplete combustion (CO, NO, _H2 S, SO) and complete combustion (steam,_CO2, _NO2, _N2, _SO2, etc.). AISI 439 is used for recirculation systems, capture and neutralization of exhaust gases. Resistance to aggressive gas environments makes AISI 439 steel used in exhaust systems, furnace equipment - exhaust systems, chimneys. Chromium steels have minimal coefficient of thermal expansion and increased thermal conductivity in comparison with austenitic nickel-containing grades. This predetermines their use in heat exchange systems such as cooling towers. The low coefficient of thermal expansion ensures reliable fitting and accelerated heat transfer during cooling of food tanks (with water, glycol or similar media). Chromium steel tubing and weldments have minimal dimensional variation with temperature fluctuations, reducing destructive fatigue stresses with temperature fluctuations, preventing unexpected leaks from hydraulic connections.

Food applications

Ferritic steels similar to AISI 439 are popular in the wine industry. They are approved for use in contact with wine, must, cognac alcohol, as well as other wine products. It is allowed to use such steels (08Cr17T) for producing equipment used in meat and dairy industry at temperatures up to 140 °C.

Steel AISI 439 is in demand in the production of food processing equipment (hygienic processing of raw materials, equipment and products, separating, mixing, sorting, grinding, packing, heat treatment, transportation). All steels of this 400 series, including AISI 439, can not only replace nickel grades, but also significantly exceed them in a number of properties, especially for food processing equipment.

Compliance with SNIP regulations

AISI 439 fully meets the state standards SNIP and is very promising in the production of equipment for processing and food industry: meat, butter, baking, spirits, beer and soft drinks, confectionery, liquor and others.

Other spheres of application

- automotive industry;

- transport engineering;

- Civil construction and design;

- Production of kitchen utensils, table setting;

- production of sinks, washing machine parts, drains, trays and drums for dishwashers

- Manufacture of interior and exterior fittings.

The use of nickel-free economically alloyed stainless steels (430 analogues) in processing and food industries is regulated by the corresponding regulations.

Temporary resistance at high temperatures:

Influence of high temperature

AISI 439 does not harden by heat treatment, has good resistance to scaling and maintains useful service properties up to 850 °C. It is positioned as heat-resistant, but the actual operating temperature depends on the aggressive environment.

Welding

Good resistance to welding by all methods and does not lose corrosion resistance in places where it is welded, provided that post-welding treatment such as passivation, etching/cleaning is carried out. Arc welding in an inert gas atmosphere requires minimum energy consumption. Welded surface is located below the welding tool. Wire Св-07Х25Н13, 309L, Св-08Х25Н13БТЮ is used as an additive material. Electrodes or wire with AISI 439 base can be used. To ensure corrosion resistance, remove scale, process discoloration places by pickling or brushing with stainless steel brushes and passivate by cold 10-20% HNO3 solution. Further thorough washing and drying is necessary.

Supply

All products are AISI 439. certified. Technical documentation includes data on chemical composition, limiting percentage of impurities, and mechanical properties of products. From us you can buy in bulk any semi-finished products for large-scale productions. We also offer optimum conditions for retail buyers. The high level of service and responsiveness of service is the face of our company.

Buy at the best price

Evek GmbH has a diverse range of stainless alloys in stock. We supply certified products of domestic and foreign manufacturers. Our staff is always happy to assist you with qualified assistance in choosing metal products. We have some of the most experienced consulting managers. Strict adherence to production standards, excellent quality of products and minimal lead time are the face of our company. Discount discounts have been introduced for regular customers.