History

Stainless steel is a relatively recent phenomenon. In 2013, we will celebrate the centennial of its introduction. Exactly one hundred years ago, the Englishman Harry Brearley, who experimented with different kinds of alloys, discovered the ability of steel with high Cr content to resist acid corrosion.

Chemical composition

There is what is known as the N/8 rule. If chromium, for example, is added to iron or another metal that is not resistant to corrosion, the protective effect can be seen in steps of 1/8, ¼, 3/8 , etc. of the alloying component. Stainless steel is mainly alloyed with 12-20% Cr and Ni, and a smaller percentage of other metals: manganese, titanium, cobalt, niobium, molybdenum. Silicon, carbon, and very little - thousandths of a percent of sulfur and phosphorus - are added to steel to give it the right qualities. 13% of chromium makes the alloys stable in mildly aggressive environments, and over 17% - in more aggressive oxidizing and other environments. The main reason for the corrosion resistance of stainless steel is associated with the formation of a thin film of insoluble oxides of chromium and nickel on the surface.

Classification

By chemical composition, stainless steels are divided into chromium (includes martensitic, ferritic and semi-ferritic); chromium-nickel and chromium-manganese-nickel (includes austenitic, austenitic-ferritic, austenitic-carbide and austenitic-martensitic)

Martensitic and martensitic-ferritic steel

Resistant to the action of soil and atmospheric humidity, weak solutions of salts and acids. Has high mechanical properties. It is used as consumables - cutting tools, knives, for resilient elements and constructions in contact with slightly aggressive media. These are steels of 30X13, 40X13 grades and so on.

Ferritic steel.

They serve for the manufacture of products working in corrosive oxidizing environments (eg solutions of _HNO3, _{H3 PO4}) in ammonia solutions, ammonium nitrate and other aggressive environments in the food and light industry, as well as in the energy sector for heat-exchange equipment. This type of steel includes steels of 400 series.

Austenitic Steel

It is strong, ductile and corrosion-resistant in most working environments and is quite technologically advanced. This steel has found the widest application as a structural material in mechanical engineering. They are steels of the 300 series. It is produced with the addition of titanium and niobium. Prone to intergranular corrosion. The tendency to intergranular corrosion is reduced by a low percentage of carbon to 0.03%. Such steels are usually heat-treated after welding. In iron and nickel alloys, the austenitic structure of the metal stabilizes and the alloy becomes a weakly magnetic material.

Austenitic-ferritic steel.

It has a higher yield strength (compared with austenitic single-phase steels), lower nickel content and good weldability. It has no grain growth while retaining the two-phase structure. These steels are used in a wide variety of industries: industrial chemistry, engineering, aviation, shipbuilding. These are steels of 08X22H6T, 08X21H6M2T, 08X18G8H2T grades.

Austenitic-martensitic steel

It is characterized by corrosion resistance, higher strength and manufacturability. These are steels of 07Cr16Ni6, 09Cr15Ni9Yu, 08Cr17Ni5M3 grades.

Steels of iron-nickel and nickel base.

They are used for chemical equipment operating in sulfuric and hydrochloric acids. They are alloys of 04XHN40MTDU grade, nickel-molybdenum alloys of H70MF type, chromium-nickel alloys of XH58V type and chromium-nickel-molybdenum alloys of XH65MV, XH60MB type.

Application

It is impossible to imagine modern life without stainless steel. In 2010 the volume of its smelting amounted to 25 million tons. It is used everywhere from food industry for making cookware to industrial chemistry and defense. Stainless chromium steels are used to manufacture turbine blades, parts of hydraulic presses and crackers, cutting tools, springs, and household appliances. Chromium-nickel and chromium-manganese-nickel steels are used to produce cutlery and utensils. Of stabilized austenitic grades - welded equipment for aggressive environments, as well as parts operating at temperatures of 550-800 ° C.

Buy, price

Evek GmbH sells rolled steel products at the best price. We deliver stainless steel of different brands in a wide range. All batches have quality certificate for compliance with standards and technical conditions of use. The certificate marks the manufacturer, alloy grade, melting number, mechanical properties of the parts, chemical composition and the results of additional tests. In our company you can buy the most various products for large-scale productions. A wide choice, comprehensive advice of our managers, reasonable prices and timely delivery determine the face of our company. In case of wholesale purchases there is a system of discounts.