Optim 500 ML structural steels
Optim™ 500 ML structural steel is easy to weld, bend and process in workshops and on site. Its high strength and good
flangeability 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 ensure
accuracy, 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 © 2013 Rautaruukki Corporation. All rights reserved.
Document printed on 07.10.2013
www.ruukki.com
Optim 500 ML structural steels
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
Yieldstrength
ReH MPa Minimum
Tensile strength
Rm MPa
Elongation
AMinimum
Impactstrength, Minimum
t °C Charpy V J
8 ­ 16
500
570 ­ 720
16
­50
27
16.01 ­ 40
480
570 ­ 720
16
­50
27
40.01 ­ 60
470
560 ­ 710
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, %
(cast
analysis)
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Optim 500 ML structural steels
C
Maximum
Si
Mn
P
S
Al
Nb
V
Ni
N
Ti
Maximum Maximum Maximum Maximum Minimum Maximum Maximum Maximum Maximum Maximum
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: 0.43
Pcm 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 steel
structures 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 for
installation. So, unnecessary material and storing costs can be avoided. If ordered, the products are delivered as shop­
primed, bevelled and bent.
Bevelling
Precision cut plates with a bevelled edge are components that can be delivered directly to the installation site, which saves
time and reduces transport and storage costs. The dimensionally accurate groove ensures uninterrupted automated welding
and fitting.
Bent plate products
Bent plate products are components that are ready to be delivered to the installation site, which is beneficial in terms of
schedule as well as transport and storing costs. If needed, the products can also be ordered as shop­primed, furnished with
welding 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 and
workshop processing can be carried out with no need for preheating in normal conditions. Before welding high­strength
steels, it must be ensured that the weld grooves are dry and clean. Moisture and other external hydrogen sources such as
grease, 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 the
requirements set by the properties of the parent metal, such as strength and impact strength, must be met. The joint type
and welding position also affect the choice of welding consumables. It is recommended to use matching welding
consumables 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 thick
plates. The welding consumables and methods used must be of sufficiently low hydrogen (HD ≤ 5 ml/100 g, ISO 3690) in
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Optim 500 ML structural steels
order to ensure good welding results. Welding consumables must be used, stored and re­dried, if necessary, in strict
compliance 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 steel
structures can be joined with these welding consumables at a workshop temperature of +20 °C without preheating. When
using the minimum weld energy of 1.0 kJ/mm, it is recommended to increase the working temperature to +75 °C in cases
where 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 repair
welding, light preheating is recommended. In case of back welding, preheating of 50 °C to 75 °C is sufficient to dry the weld
point and prevent cracking. The positive impacts of light preheating have been proven in a number of practical welding jobs
carried out on complex and rigid structures.
If an overmatching welding consumable is used when welding Optim 500 ML steels, preheating requirements must be
decided on the basis of the carbon equivalent of the welding consumable. In this case, the welding consumable hardens
more than the parent metal.
Forming
Optim 500 ML can be easily formed in workshop processing. As a result, components previously made by welding can now
be made by bending, which shortens the throughput time and thus reduces costs.
Minimum permissible bending radius, bending angle 90°
Thickne 8 ss mm:
(8) ­ 10
(10) ­ 12
(12) ­ 14
(14) ­ 16
(16) ­ 18
(18) ­20
Minimum 9.5
permissi
ble
inside
bending
radius mm:
12
14.5
17
19
21.5
24
No limitations on bending direction.
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Optim 500 ML structural steels
The successful bending and forming of high­strength steel structure requires the use of good workshop technology. Worn
forming tools, insufficient lubrication, scratches on the plate surface and edge burrs will reduce the quality of forming. Plates
taken 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 structural
requirements necessitate the reduction of residual stresses, then stress relieving can be carried out at 530–580 °C. Heating
the steel to temperatures higher than 580 °C may reduce its strength, and for this reason hot working and normalising are
prohibited. Heat treatment
Temperature °C
Treatment time and manner of cooling
Stress relieving
530 – 580
(Target 560)
2 minutes/millimetre thickness, minimum 30 minutes
Slow 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 longer
heating periods are required for a specific purpose, the temperature must be lower. The applicable recommendations for
flame 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 piece
when mechanically cutting high­strength steel grades. Plates taken from cold storage must be allowed to warm up to room
temperature (+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, Ultra­sonic
testing and General terms of sale.
The content of this document has been created from web page last updated 27 Aug 2013
Our sales and technical support are happy to give you more information. Visit www.ruukki.com/contact­us.
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