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The SIQUAL brand includes a broad selection of special types of steel for various purposes:

  • Steel for pressure vessels and boiler plates
  • Steel for quenching and tempering
  • Case-hardening steel
  • Spring steel
  • Non-alloyed structural steel
  • Weathering steel


Get more detailed information about SIQUAL grades on: 

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Below, you can browse and download the technical datasheets for our most popular grades. For the complete production programme, please contact our sales representative.

Steels for pressure vessels and boiler plates

SIQUAL steels for pressure purposes are categorised depending on their application:

  • Steel for cryogenic applications

Grade SIQUAL 5663, more commonly known as X7Ni9 or 9% Nickel steel, performs best at temperatures between –50 and –196 °C. Thanks to its excellent mechanical properties, wall thickness can be reduced, creating cost-efficient solutions for constructing LNG storage and transportation tanks.

  • Steel for applications at moderate temperatures

These grades are suitable for applications within the temperature range of 0 to 400 °C. Thanks to good weldability and toughness, these steels are especially suitable for tanks in the oil and gas industry.

  • Steel for applications at elevated temperatures

These grades are suitable for applications at temperatures up to 600 °C. Due to maintaining high strength at elevated temperatures, good heat conductivity and corrosion resistance, they can be used for pipes, boilers and furnace parts used in the petrochemical industry and in oil refineries, for industrial flanges and heat exchangers.

4903 7335 7336
7362 7380 7386

Steel for quenching and tempering

These steel grades must be quenched and tempered to achieve the desired strength and plasticity. Depending on the cross-section and the amount of alloying elements, they need to be cooled in water, oil, or air after austenitisation. These steel grades are mostly delivered in the annealed condition, allowing for easy mechanical processing, and final quenching and tempering by the customer to achieve the required mechanical properties. Alternatively, some grades are also available as quenched and tempered quarto plates. They are used in machines, machine parts, and constructional engineering.

0913 1151 1191

Case-hardening steel

These steel grades must be enriched with carbon to achieve the desired high surface hardness and a tough centre. Our products are delivered in the annealed condition. After mechanical processing, the customer can carburise the surface of the end product, and then quench and temper it to achieve a final surface hardness of over 60 HRC. They are used for knives, agricultural and mining machinery, safety-relevant parts in the automotive industry, gears, and high-stressed components.

0503 5531 7016

Spring steel

SIQUAL spring steels are intended for products expected to have high strength, good toughness, and high yield strength after final heat treatment. They are used for vibration-resistant moving parts. The products are formed in the annealed or spheroidization-annealed condition, but the desired properties are obtained by quenching and tempering made by the customer. By special agreement, delivery in quenched and tempered condition is also possible.

1231 1248 1260

Non-alloyed structural steel

Non-alloyed structural steel is characterised by high strength and good elongation. At the same time, it retains good formability and weldability. They are used in the production of various forms of steel, machine parts, bridges, and agricultural machinery parts.


Weathering steel

Compared to non-alloyed steel, weathering steel has increased resistance to atmospheric corrosion. Under different weather conditions, a protective oxide layer is formed on the steel surface. These steel grades are alloyed with copper, chromium, nickel, and phosphorus, forming a protective layer in the form of iron oxide. Resistance to atmospheric corrosion depends on the shape of the structure and the environment into which the structure is placed. They are used for different types of structures, bridges, fences, sculptures and roof tiles.


Luka Vindišar

Sales Manager