Advantages of stainless steel are the high corrosion resistance, good process ability (weldability), high heat resistance, ease of maintenance, and excellent hygienic properties. In addition, stainless steel has a very attractive appearance, is durable, and highly cost-effective. thyssenkrupp Materials Bulgaria offers to its customers a broad range of stainless steel flat, long, and tube materials, both austenitic and ferritic.
The austenitic iron-chromium-nickel grades represent 80% of the world market for stainless steel. Their face-centered cubic crystal structure gives them excellent ductility and toughness, from cryogenic temperatures to several hundred degrees Celsius. Furthermore, these materials can be readily welded to give sound metallurgical joints, greatly facilitating their use. Depending on the intended application, i.e. on the required service properties, together with the conditions of implementation, a number of other alloys have been developed with specific property combinations. The principal applications are the storage and treatment of foodstuffs, collective catering, and hospital equipment. They also constitute the standard materials for chemical engineering equipment and are widely employed for domestic utensils and appliances. In the as-delivered condition, austenitic chromium-nickel(-molybdenum) steels have higher elongation values and generally greater corrosion resistance. In contrast to the ferritic chromium (-molybdenum) steels, they are not magnetizable in the as-delivered condition.
The ferritic stainless steels are characterized by their structure, which remains fully ferritic at all temperatures. Their heat resistance is lower than austenitic steels. Ferritic chromium (-molybdenum) steels generally have a lower elongation and corrosion resistance than austenitic Cr-Ni-(Mo) steels. This leads to demonstrably less distortion when used at high temperatures. The most common grades in this group contain 11-12% chromium and a low carbon content of less than 0.03%. The ferritic structure offers excellent fabricability and sufficient corrosion resistance for various applications. 11% chromium steels are used in automotive exhaust systems, where the atmospheres are moderately aggressive. The second group is X6Cr17/1.4016, which contains 16.5% chromium and 0.05% carbon. In addition to preventing intergranular corrosion and to improve weldability, stabilizing elements like titanium, niobium, and vanadium are added in sufficient quantities. The principal application of the 17% chromium grades is in the manufacture of domestic implements and appliances.