Stainless steel

The origins of stainless steel date back to the 19th century, when work began in France on the addition of chromium to carbon steel to protect the material in acidic environments. As such, austenitic steel (with chromium and nickel additions) was patented by German engineers at the Krupp plant.
However, it was not until the early 20th century, when Harry Brearley was working on an alloy to improve the durability of rifle barrel tubes, that the nomenclature of stainless steel began to be used. The Englishman succeeded in this by adding chromium and nickel to the alloy in the right proportions. Practically in parallel to the Englishman's work, a method for the mass production of this steel was developed in France

We are currently dealing with it in almost every area of life. It is widely used in the food, chemical, petrochemical, automotive, construction and many other industries.

Right next to the precise choice of steel grade, of which there are plenty to choose from! (the most common are shown in the table below) for some components, the surface finish is equally important. A surface characterised by greater roughness (with deeper grooves) is more prone to corrosion. as chloride ions can more easily collect in its area and destroy the passive layer.
In contrast, on a polished surface, the same ions have this task made much more difficult. This is why it is so important to precisely define and agree on the favourable characteristics of the surface finish.

Types of stainless steel
due to the crystalline structure

Ferritic steel - owes its name to the ferrite present in its structural structure. The main alloying addition, apart from a small amount of carbon (1.2%), is chromium (11.5-17%). Some grades are also enriched with molybdenum (Mo), titanium (Ti) or niobium (Nb). It is a magnetic steel. It cannot be hardened by heat treatment during production, but can be hardened by cold working.

Application:
automotive, food, oil, coke; chemical industry - and also for the manufacture of kitchen equipment, household appliances and components for photovoltaic assembly.

Austenitic steel - The name refers directly to the structure, i.e. the so-called austenite. It contains up to 0.15 % of carbon and 16-21% of chromium and, above all, a minimum of 8% of nickel (Ni) additives, giving it a high corrosion resistance. This property increases with further alloying additions - such as chromium, molybdenum and titanium. Unlike martensitic steel, austenitic steel is not hardened during the production process. It also has almost twice the elongation values of ferritic steels.

Application:
environments characterised by high temperatures, high humidity, high mechanical stress; used primarily in the chemical and petrochemical industries, construction, aeronautical, railway and shipbuilding, structural engineering or in the manufacture of white goods.

Martensitic steel - Austenitic steel cooled during the production process hardens and acquires a martensitic structure. Although not as corrosion resistant as austenitic and ferritic steels, it has high strength properties and high abrasion resistance. For a stainless steel, it has a relatively high carbon content (0.08 to 0.5%). The chromium content of this steel is 12-17.5%. Martensitic steel is characterised by significantly higher hardness and wear resistance than ferritic steel and austenitic steel, but is difficult to weld. The martensitic structure obtained is magnetic.

Application:
Low-aggressive environments; used primarily to manufacture: screws, springs, pins, pump parts, valves for hydraulic presses, knives, cutting tools, surgical instruments.

Duplex steel - which is a steel with a two-phase ferritic-austenitic structure that contains 16-29% chromium, up to 1.2% carbon, 3.5-8% nickel, 0-4.5% molybdenum and the addition of nitrogen. Duplex steels are steels that retain high corrosion resistance, also in acidic environments. They fulfil at a high level the strength properties that characterise ferritic steels and have a relatively low coefficient of thermal expansion compared to austenitic steels.

Application:
in environments with a high chlorine content (e.g. water desalination, biofuel production, hydraulics - in oil and gas pipelines), as a replacement for austenitic steels in various structures and projects in the food or chemical industries.

Heat-resistant steel - that is steel resistant to the corrosive effects of oxidising gases (chemical corrosion), abrasion and melting in high-temperature environments. The upper limit of heat resistance is between 800 - 1200 degrees C - depending on the composition of the steel grade.

Application:
in environments exposed to fire and/or high temperatures (furnace components, steam boilers, hot gas fans, carburisation boxes, combustion chambers of gas turbines and valves of reciprocating combustion engines)

Stainless steel corrugated sheets

DIN 59220

ASTM A793 - Pattern B

 

Perforated sheets

Perforated sheets are manufactured from the highest quality stainless steel, acid resistant, aluminium, brass and copper. They are characterised by durability, lightness and universality of application. They are used in the engineering, food, agricultural and construction industries and as decorative elements.

Holes are made in various shapes, including: circular, cylindrical, conical, conical-cylindrical, square, rectangular, hexagonal, bowl-shaped, elongated and others according to individual designs.

Due to their widespread decorative use, perforated sheets are often covered with protective and decorative coatings.

Rv

Round holes,
60° passing system

rg

Round holes,
straight 90° system

rd

Round holes,
45° diagonal arrangement

qg

Square holes,
straight 90° system

qv

Square holes,
60° passing system

qd

Square holes,
45° diagonal arrangement

lv

Longitudinal openings,
system passed

lg

Longitudinal openings,
simple system

hv

Hexagonal holes,
hexagonal,
60° passing system

deco

Holes
decorative