RAEX 700 MC Optim offers both strength and formability at the same time.  The surface quality, dimensional and geometrical accuracy and uniformity of properties of this steel are all top class.  Steel structures can be made lighter, which means that the payload of machines and equipment can be increased and fuel consumption reduced.  The letter ‘M’ indicates the thermo mechanical rolling of these steel grades, which is their delivery condition.  The letter ‘C’ means that the steel is suitable for cold forming in compliance with EN 10149-1.

Applications:

Frame structures of mobile vehicles, surface structures of commercial vehicles, frames and booms of forestry vehicles, crane arms and other lifting equipment, load handling equipment and masts.

Chemical Composition Content % (ladle analysis)

C max.	Si max.	Mn max.	P max.	S max.	Al max.	CEV %
0.10	0.20	2.00	0.020	0.010	0.015	0.37 ave. 0.41 max.

In addition, niobium (Nb), vanadium (V), molybdenum (Mo), titanium (Ti), or boron (B) may be used as alloying elements either singly or in combination.

CEV = C + Mn/6 + (Cr + Mo = V)/5 + (Ni + Cu)/15

Mechanical Properties

Plate Thickness mm	Yield Strength ReH N/mm² minimum	Tensile Strength Rm N/mm 2 minimum	Elongation % Minimum A80¹)    A5	Impact Strength Longitudinally min. t°C         KV J
3.0 – 8.0	700	750 – 930	--        15	-20             40

The yield strength and tensile strength are tested in longitudinal direction, but guaranteed both in longitudinal and transverse direction.  Elongation is tested longitudinally.  Impact strength is determined using the Charpy V test.  For thickness less than 10mm the width of the test piece is equal to the strip thickness and correspondingly the guaranteed values are lower in direct proportion such that for 5mm a value of 2/3 of the value in the table is guaranteed.  Impact tests are not carried out on thickness of less than 5mm, but the impact strength is guaranteed.

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¹) Elongation A80 is used for thickness below 3mm.

Processing

Heat Treatment

Welded structures do not normally require any heat treatment after fabrication.  If stress relieving is required, however, it must be carried out in accordance with the following recommendations:

Heat Treatment Recommendations

Heat Treatment	Temperature °C	Treatment time & manner of cooling
Stress relieving	550 – 600 (target 570)	2 minutes/mm thickness, min. 30 minutes. Slow cooling in the furnace

Too high temperature and long treatment time may weaken mechanical properties.

The strength of the thermo mechanical treated steel may be reduced if the temperature exceeds 650°C, and

for this reason normalizing or hot working are prohibited.

Welding

The welding is, in spite of its high strength, easier than the welding of conventional softer grades.  As a result of thermo mechanical treatment, carbon equivalent values are low in relation to its strength.  In addition, weldability has been improved by selection of suitable alloying elements and by ladle treatment.  In design and workshop practice this good weldability means that preheating is not necessary under normal conditions.  Before welding it must be ensured that the surfaces of the weld run are both dry and clean.  The welding materials and methods must be of sufficiently low hydrogen.  Materials must be stored and dried, if necessary, in accordance with the manufacturers instructions.

The weld material properties, strength etc. must, in the main, be the same as those of the base material (matching).  There are, however, some exceptions to this general rule in the case of high strength steels.  This

is the case for the higher strength RAEX 700 MC steels, which mean that consumables of a lower strength than

the steel (undermatching) may be used, provided that the weld is situated in a less stressed part of the structure. 

A narrow zone pf material softer than the base material may be formed in the welded joints.  The softer zone is similar to that in quenched and tempered steel and does not usually affect the strength of the structure. The width of this zone can be limited by avoiding the use of unnecessarily high welding energy.

Forming

RAEX 700 MC can easily be bent in the workshop.  As a result of this, components previously made by welding can now be made by bending, which shortens the throughput time and so reduces costs. 

Successful utilisation of the excellent formability requires the use of good workshop techniques.  This requirement becomes more important the higher the strength of the steel is.  Worn tools, insufficient lubrication, scratches on the surface of the steel as well as edge burns will all reduce the quality of the forming.  Also shot blasting of the surface may reduce formability.  Plates taken from cold storage must be allowed to warm up to room temperature before being formed.

Minimum permissible inside bending radius, bending angle 90°C

Minimum permissible inside bending radius mm

Thickness mm (2.5) – 3	(3) – 4	(4) – 5	(5) – 6
3.5	5.0	6.0	8.0

No limitations on bending direction.

Cutting

RAEX 700 MC can be cut easily using thermal methods such as flame, plasma and laser cutting.  When cutting mechanically, attention must be paid to the stiffness of the equipment, the blade condition and clearance, and the supporting of the work piece.  Plates taken from cold storage must be allowed to warm up to room temperature before being cut