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Steel grades

 

HISTAR® AND FRITENAR® trademark steels

The HISTAR® and FRITENAR® trademark steels meet all requirements of the applicable structural steel standards. They exceed the requirements and offer supplementary guarantees.

HISTAR® and FRITENAR® are structural steel grades with a low alloy content, combining high strength, good toughness and superior weldability. HISTAR® steels are available in yield strengths of 355 MPa and 460 MPa, FRITENAR® steels are available in 355 MPa. The application of the innovative in-line heat treatment QST (Quenching and Self-Tempering) allows all HISTAR® grades, unlike most standard grades, to offer improved guaranteed values for yield strength over the whole product range. A comparison between the yield strengths of HISTAR® grades and conventional grades is shown below:

 

HISTAR® steels are delivered in a thermomechanically rolled condition in accordance with the European Technical Approval ETA-10/0156. They comply with the requirements of the European standards EN 10025-4: 2004 for weldable fine grain structural steels.

The steels are typically delivered with a Si content ranging between 0,14% and 0,25%, and are as such capable of forming a zinc layer during hot-dip galvanisation. As the phosphorus content of these steels is usually lower than 0,035%, it does not have any influence on the final thickness of the coating in the considered Si range.

HISTAR® and FRITENAR® steels can be cut with a torch and machined using the process normally applied to structural steel of the same level of strength. Due to the low carbon equivalent, preheating in order to prevent cracking is generally not necessary for product temperatures >0°C.

HISTAR® and FRITENAR® steels offer good weldability for manual and automatic processes, provided the general rules for welding are respected. Due to the low carbon equivalent values of these steels, preheating is not necessary within the range of heat inputs of 10-60 kJ/cm and for temperatures of the structure over 0°C, provided that low hydrogen consumables are used.

Under these conditions, no preheating is required for welding HISTAR® and FRITENAR® steels over the whole thickness range. As for the usual structural steels, drying before welding is recommended for ambient temperatures below 5°C and when the surface is wet.

If stress relieving is required for HISTAR® and FRITENAR® steels, it is performed at temperatures between 530°C and 580°C. The recommended holding time is 2 minutes per mm product thickness, but not less than 30 minutes and not more than 90 minutes.

For a short reheating of the entire thickness of HISTAR® and FRITENAR® beams, the flame straightening temperature should not exceed 650°C. For local reheating of the surface only, a flame straightening temperature of up to 900°C is allowable.

Designation system for steels

The European standard EN 10027: 1992 defines, in combination with the CEN report CR10260, the designation system for steel. The usual symbols for structural steels are shown here.

The following table shows a list of corresponding designations between the European standards as well as the HISTAR® grades with those from the American, Canadian, Japanese and the former national European standards.

Structural Steels

The main requirements of the standards regarding the mechanical characteristics and the chemical composition of the available structural steel grades are given hereafter:

 

Other grades (Japanese or Canadian CSA standards for instance) are available upon request.

The mechanical characteristics of ArcelorMittal's sections are improved by precise control of the temperature during the rolling process. Steels, produced using thermomechanical rolling (delivery condition M), feature improved toughness values thanks to a lower carbon equivalent and a fine microstructure when compared with normalised steels. With regard to their technological properties, the thermomecanically rolled steels have good cold forming properties. Similar to conventional structural steels, they can be flame straightened provided specific maximum temperatures are not exceeded. In case stress relieving is considered for reducing residual stresses, the usual parameters concerning temperature range and heating time according to the rules of practice must be applied. Hot forming, which is however uncommon for the fabrication of sections, must not be performed in accordance with EN 10025:2004.

The steels are typically delivered with a Si content ranging between 0,14% and 0,25%, and are as such capable of forming a zinc layer during hot-dip galvanisation.

 As the phosphorus content of these steels is usually lower than 0,035%, it does not have any influence on the final thickness of the coating in the considered Si range.

Steel grades for offshore applications

HISTAR® Offshore and FRITENAR® Offshore are structural steel grades especially developed for offshore applications. In comparison with HISTAR® and FRITENAR® trademark steels, the grades for offshore applications offer the following additional features:

  • improved through-thickness deformation properties with respect to the resistance to lamellar tearing (Z qualities);
  • notch impact properties in the transverse direction
  • maximum ratio between yield strength and tensile strength.

HISTAR® and FRITENAR® Offshore grades are in compliance with EN 10225: 2009.

Weldable structural steels for fixed offshore structures according to EN 10225: 2009.

Arcorox®

Weathering steel grade according to EN 10025-5 / ASTM A588 for sustainable, decorative and cost efficient structures with uncoated steel sections

Arcorox® structural shapes belong to a family of atmospheric corrosion resistant, low alloy steels for sustainable applications with focus on long service life with low maintenance costs.

By initially forming a natural, tightly adherent, protective oxide layer (patina), it strongly reduces further oxidation and thus supersedes the application of any corrosion protection system.

Therefore, along with aesthetic possibilities, Arcorox® provides durable construction even in the absence of initial painting, which enables savings  thanks to:

  • Reduced construction cost along with construction time;
  • Reduced cost of maintenance as well as time of maintenance operation;
  • No environmental impact due to absence of maintenance operations and residue.

Esthetically Arcorox uniquely suits to each building: Appearance, texture and maturity of the patina depending on time, degree of exposure and atmospheric environment.

Complete product information available on our leaflet Arcorox.

Mechanical properties and chemical composition of Arcorox.

16 Mo3 in relation with EN 10273 and EN 10028

Alloyed Steel for Elevated Service Temperatures

Thanks to its improved mechanical properties (specified up to 500°C) and improved creep resistance, 16 Mo3 alloyed steel grade is particularly recommended for use at elevated service temperatures.

This weldable steel grade is particularly relevant for use in powerplant equipment, exhaust systems, hot machine parts or incineration plants.

This special quality grade is available for sections and merchant bars. Hot-rolled sections in 16Mo3 steel are far more economical than cutting and welding plates to build up sections of 16Mo3 steel.

Mechanical properties and chemical composition of 16Mo3.