optim 500 ml structural steels - · pdf filematerials testing and sampling are carried out in...
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Optim 500 ML structural steelsOptim™ 500 ML structural steel is easy to weld, bend and process in workshops and on site. Its high strength and goodflangeability allow steel structures to be made using thinner steel plates.
Environmentally sound, durable and smart structures are guaranteed using this highstrength (500 MPa),thermomechanically rolled (M) and low temperature tough (L) structural steel grade.
Optim 500 ML has no equivalence in any structural steel standards.
Applications: • Wind power plants
• Tanks
• Framework structures
• Vehicle structures
• Lifting and mobile equipment
The information on our web site is accurate to the best of our knowledge and understanding. Although every effort has been made to ensureaccuracy, the company cannot accept any responsibility for any direct or indirect damages resulting from possible errors or incorrect
application of the information of this publication. We reserve the right to make changes.
Copyright © 2014 Rautaruukki Corporation. All rights reserved.
Document printed on 28.10.2014 www.ruukki.com
Dimensions
Product shapes
Heavy plates and shop primed plates.
Heavy plates
Thickness mm Width mm Length m
860 1901 3300 2 15
Minimum width depends on the thickness.
On request, plate lengths 15 to 22 m can be delivered within the limits of the maximum weight about 12 tonnes.
The Optim 500 ML grade can be delivered as Z Plates.
More detailed information on dimensions is provided in the Plate Products Production Programme
Tolerances
Tolerances on dimensions and shapes:
• Heavy plates according to EN 10029.
• Thickness tolerances for plates EN 10029 Class A.
• Flatness guarantee is 6 mm/m.
Surface quality
Surface quality: EN 101632 Class A3
Heavy plates are delivered in asrolled condition or in shopprimed condition.
Properties
Materials testing
Materials testing and sampling are carried out in compliance with EN 100254.
Mechanical properties
Thickness mm YieldstrengthReH MPa Minimum
Tensile strengthRm MPa
ElongationAMinimum
Impactstrength, Minimumt °C Charpy V J
8 16 500 570 760 16 50 27
16.01 40 480 570 760 16 50 27
40.01 60 470 560 760 16 50 27
The tensile test is made transversely and impact test longitudinally to the rolling direction in compliance with EN 100254.
Chemical composition
Content, %(castanalysis)
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CMaximum
SiMaximum
MnMaximum
PMaximum
SMaximum
AlMinimum
NbMaximum
VMaximum
NiMaximum
NMaximum
TiMaximum
0.18 0.50 1.70 0.020 0.015 0.02 0.05 0.12 1.00 0.015 0.05
Carbon equivalent values (CEV)
CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15 Pcm = Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B
CEV maximum: 0.43Pcm maximum: 0.26
Prefabrication services
Wide flats
Wide flats from plate are dimensionally accurate and ready for assembly. Wide flats speed up the manufacture of steelstructures and avoid wasting of material.
Flat cut shapes
Flat cut shapes will decrease the throughput time of installation. The customer will receive the components ready forinstallation. So, unnecessary material and storing costs can be avoided. If ordered, the products are delivered as shopprimed, bevelled and bent.
Bevelling
Precision cut plates with a bevelled edge are components that can be delivered directly to the installation site, which savestime and reduces transport and storage costs. The dimensionally accurate groove ensures uninterrupted automated weldingand fitting.
Bent plate products
Bent plate products are components that are ready to be delivered to the installation site, which is beneficial in terms ofschedule as well as transport and storing costs. If needed, the products can also be ordered as shopprimed, furnished withwelding bevels, and cut to shape. Premarked matchmarks facilitate installation.
Processing instructions
Welding
The welding of Optim 500 ML grade is easy. The alloying and carbon equivalent are low for a steel with such high strength.This ensures excellent weldability both in engineering workshops and on site. Thanks to good weldability, design andworkshop processing can be carried out with no need for preheating in normal conditions. Before welding highstrengthsteels, it must be ensured that the weld grooves are dry and clean. Moisture and other external hydrogen sources such asgrease, oil and paint must be carefully removed from the weld area.
Download information about welding
Welding consumables
Welding consumables are chosen according to the structural requirements of the application. A selection criterion is that therequirements set by the properties of the parent metal, such as strength and impact strength, must be met. The joint typeand welding position also affect the choice of welding consumables. It is recommended to use matching weldingconsumables which give the weld metal a yield strength of 500 MPa or slightly higher.
In case of rigid joints, undermatching welding consumables can also be used for the welding of the back weld of thickplates. The welding consumables and methods used must be of sufficiently low hydrogen (HD ≤ 5 ml/100 g, ISO 3690) in
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order to ensure good welding results. Welding consumables must be used, stored and redried, if necessary, in strictcompliance with the manufacturer’s instructions.
Working temperature
The working temperature for welding is defined according to the following factors:
• Hardening of the parent material (carbon equivalent)
• Hardening of the welding consumable (carbon equivalent)
• Hydrogen content of the welding consumable
• Arc energy
• Combined plate thickness
Lowcarbon welding consumables minimise the need to increase the working temperature. Even the most robust steelstructures can be joined with these welding consumables at a workshop temperature of +20 °C without preheating. Whenusing the minimum weld energy of 1.0 kJ/mm, it is recommended to increase the working temperature to +75 °C in caseswhere the combined plate thickness exceeds 100 mm. Lower thicknesses can be welded without preheating.
Combined plate thickness
• Tjoint: t = t1+t2+t3• Butt joint: t3 = 0
Picture illustrates an example on the calculation of combined plate thickness.
If lowarc energy (less than about 1.0 kJ/mm) must be used in, for example, tack welding, back welding or small repairwelding, light preheating is recommended. In case of back welding, preheating of 50 °C to 75 °C is sufficient to dry the weldpoint and prevent cracking. The positive impacts of light preheating have been proven in a number of practical welding jobscarried out on complex and rigid structures.
If an overmatching welding consumable is used when welding Optim 500 ML steels, preheating requirements must bedecided on the basis of the carbon equivalent of the welding consumable. In this case, the welding consumable hardensmore than the parent metal.
Forming
Optim 500 ML can be easily formed in workshop processing. As a result, components previously made by welding can nowbe made by bending, which shortens the throughput time and thus reduces costs.
Minimum permissible bending radius, bending angle 90°
Thickness mm:
8 (8) 10 (10) 12 (12) 14 (14) 16 (16) 18 (18) 20
Minimumpermissibleinsidebendingradius mm:
9.5 12 14.5 17 19 21.5 24
No limitations on bending direction.
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The successful bending and forming of highstrength steel structure requires the use of good workshop technology. Wornforming tools, insufficient lubrication, scratches on the plate surface and edge burrs will reduce the quality of forming. Platestaken from cold storage must be allowed to warm up to room temperature (+20 °C) before being formed.
Heat treatment
The Optim 500 ML grade is used in structures for which heat treatment is usually not required after welding. If the structuralrequirements necessitate the reduction of residual stresses, then stress relieving can be carried out at 530–580 °C. Heatingthe steel to temperatures higher than 580 °C may reduce its strength, and for this reason hot working and normalising areprohibited.
Heat treatment Temperature °C Treatment time and manner of cooling
Stress relieving 530 – 580(Target 560)
2 minutes/millimetre thickness, minimum 30 minutesSlow cooling in furnace
Cutting
The steel can be easily cut using thermal cutting methods such as flame, plasma and laser cutting.
Flame straightening
Flame straightening is permitted at a surface temperature of a maximum of 600 °C for short periods of time. If longerheating periods are required for a specific purpose, the temperature must be lower. The applicable recommendations forflame straightening are published in CEN/TR 10347:2006 (E) “Guidance for forming of structural steels in processing.”
Occupational safety
Special attention must be paid to the stiffness of cutting tools, blade condition, clearance and supporting of the work piecewhen mechanically cutting highstrength steel grades. Plates taken from cold storage must be allowed to warm up to roomtemperature (+20 °C) before cutting.
Order & delivery
The delivery condition is thermomechanical rolled (TM).
Inspection document
Inspection documents are in accordance with EN 102043.1.
General delivery information for hotrolled steels
General delivery information for hot rolled steels can be found from documents Markings and packing, Ultrasonictesting and General terms of sale.
The content of this document has been created from web page last updated 31 Aug 2014Our sales and technical support are happy to give you more information. Visit www.ruukki.com/contactus.
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