Workshop recommendations for Armox

Workshop
Recommendations
This leaflet contains general suggestions and calculation models. SSAB does hereby expressly exclude any liability whatsoever for their suitability for individual applications. It is the
responsibilty of the user of the manual to adapt the recommendations contained herein to
the requirements of individual applications.
Project manager marketing Johan Lundin, Technical advisors Mikael Ringholm, Per Hansson
CUTTING RECOMMENDATIONS
Protection plates manufactured by SSAB have lean chemical compositions. This simplifies the cutting process.
However, to get the best cut quality, Armox should be cut under controlled conditions as described below.
Armox 370T
CL1 & CL2
Armox 440
Armox 500T
Armox 600T
Armox
Advance
Recommended cutting method
• Abrasive waterjet
Up to 15 mm
Up to 25 mm
Up to 15 mm
Up to 10 mm
-
• Plasma
• Laser
• Abrasive disc
• Abrasive waterjet
• Laser
15 - 25 mm
25 - 35 mm
15 - 25 mm
10 -20 mm
-
• Gas cutting at reduced speed
• Gas cutting plus preheating to 170 +- 30°C
• Abrasive disc
• Abrasive waterjet
40 - 60 mm
25 - 35 mm
40 - 60 mm
20 - 30 mm
-
Above 60 mm
Above 35 mm
Above 60 mm
Above 30 mm
Up to 7 mm
• Gas cutting plus preheating to 170 +- 30°C
plus keep warm for 4 hours at 160 +- 40°C
• Abrasive disc
• Abrasive waterjet
• Abrasive disc
ABRASIVE WATERJET
GAS CUTTING
This process can be applied to the complete range of high-hardness Armox plate,
and is recommended as the best method,
because the absence of HAZ eliminates
the risk of cracking.
This process can be applied to high-hardness Armox plate up to 80 mm thickness.
It generates a kerf of 2-5 mm and a HAZ
which is usually 4-10 mm wide.
LASER CUTTING
High-hardness Armox plate up to around
20 mm thickness can be cut using this
process. It generates a narrow kerf, usually less than 1 mm, and a narrow HAZ,
usually less than 3 mm.
PLASMA CUTTING
High-hardness Armox plate up to around
25 mm thickness can be cut using this
process. It generates a kerf, usually 3-4
mm, and a HAZ up to 5 mm. Plasma cutting can be performed under water, which
minimizes the amount of distortion.
ABRASIVE DISC
This process is usually applied to the cutting of tube and rod
but can also be adopted for straight line cutting of the complete
range of high-hardness Armox plate. The kerf is the thickness
of the disc, with little or no HAZ.
Uncontrolled gas cutting of high-hardness armour plate may result in hydrogen
cracking (also called cold cracking) which
may occur in thicknesses above 20-30 mm.
The thicker the plate, the higher the cracksensitivity.
The most effective technique to avoid cracking during and after cutting is to preheat the plate and then keep the cut parts
warm afterwords.
Preheating consists of bringing the whole plate, or at least a
100 mm wide area on either side of the future kerf, up to a
specified minimum temperature before the process begins. This
can be done by using thermostatically controlled furnaces or,
in some cases, using gas burners to maintain the temperature
throughout the process.
The same equipment can be used to keep the profiles warm
for a specific time immediately following the cutting process.
In some instances, thick plate profiles that are not prone to
overheating can be cut at low speed, which obviates the need
for preheating.
3
WELDING RECOMMENDATIONS
SSAB manufactures protection plate with lean chemical compositions which simplify welding. Armox plates
should be welded with a consumable which produces a low hydrogen content in the weld metal. Good results
require that hydrogen, which can induce cold cracking, is kept away from the weld area. Armox plates can be
welded by any conventional welding method. All Armox grades can be welded to other weldable steel.
The temperature should be maintained throughout the entire
weld operation, tack welding and root passes included.
EDGE PREPARATION
A good fit between the work pieces is essential to minimize
stresses and thereby the risk of cracking. All types of impurities on and near the edges, such as mill scale, rust, oil, paint
and moisture, should be removed before welding.
Armox plates have been developed to have as low carbon
equivalent as possible without loss in hardness, strength and
ballistic properties. Typical carbon equivalents are shown in
the table below.
TACK WELDING
During tack welding the cooling rate is more rapid which
increases the risk of cold cracking. In areas of high restraint the
minimum length of each tack weld should be 50 mm to prevent
hydrogen cracking.
Steel grade
Thickness range
Carbon equivalent1
Armox 370T
CL1 & CL2
3–150 mm
0.67–0.75 2
PREHEAT TEMPERARATURES
Armox 440T
4–30 mm
0.68–0.72
If austenitic consumables are used, the plate should be welded
at least at room temperature (18–25°C). But when welding
plates thicker than 30 mm, in combination with high levels of
restraint, preheating is recommended.
Armox 500T
3–115 mm
0.67–0.75 2
Armox 600T
4–20 mm
0.85 2
Armox Advance
5–7 mm
0.95
1) Carbon equivalent (CEV)
in accordance to IIW:
If unalloyed or low-alloyed consumables are used preheating is
necessary and dependent on plate thickness and restraint conditions.
C + Mn + Cr + Mo + V + Cu + Ni
6
5
15
2)For plate thicknesses >80 mm, please contact SSAB
Minimum recommended preheat and interpass temperatures for different plate thicknesses (mm)
Thickness 3
Armox 370 T Class 1
Armox 370 T Class 2
3-80 mm
3-150 mm
10
125°C
50°C
Armox 440 T
4-30 mm
Armox 500 T
3-140 mm
Armox 600 T
4-20 mm
150°C
75°C
125°C
20
30
175°C
100°C 125°C
40
50
200°C
60
70
80
140
100°C + austenitic
150°C
150°C 175°C
200°C
100°C + austenitic
100°C + austenitic
Armox Advance
5-7 mm
Measure the preheat
temperature here
Maximum recommended preheat/interpass temperatures
Armox 370 T
Armox 370 T Class 2
400°C
Armox 440 T
200°C
Armox 500 T
200°C
Armox 600 T
180°C
Armox Advance
150°C
Measure the temperature of the thickest
plate in the joint. If the plate is 25 mm thick,
measure the temperature 2 minutes after
heating. If the plate is 12.5 mm thick, measure the temperature after 1 minute, etc.
The interpass temperature can be measured in the weld metal or in the immediately
adjacent parent metal.
4
75 mm
Intended
weld joint
150
Welding can be carried out directly on the excellent primer,
due to its low zinc content. The primer can easily be brushed
or ground away in the area around the joint. Removing the
primer prior to welding can be beneficial, as it can minimize
the porosity in the weld and can facilitate welding in positions
other than the horizontal.
The table on the previous page is applicable to single plate
thickness when welding with a heat input of 1.7 kJ / mm. If the
ambient humidity is high or the temperature is below +5 °C,
the lowest recommended preheat temperatures given should be
increased by 25 °C. This also applies to firmly clamped weld
joints and if the heat input is 1.0-1.6 kJ / mm. Preheat temperatures for heat inputs lower than 1.0 kJ /mm can be determined
by an applicable standard for high strength steels. One example is method B in European Norm EN 1011-2.
The lowest recommended preheat and interpass temperatures
in the chart on the previous page are not affected at heat inputs
higher than 1.7 kJ / mm.
position the welds in low stress areas. Select the consumables
which produce the lowest possible level of hydrogen in the
weld metal for the given weld process.
CHOICE AND HANDLING OF CONSUMABLES
The hydrogen content should be lower than or equal to 5 ml
of hydrogen per 100 g of weld metal when welding with unalloyed or low-alloyed welding consumables. Solid wires used
in MAG and TIG welding can produce these low hydrogen
contents in the weld metal. The hydrogen content for other
types of welding consumables can best be obtained from the
respective manufacturer.
Consumables should be selected on the basis of strength and
toughness requirements in the joint. We recommendend soft
consumables with a yield strength of up to 500 MPa.
In order to achieve an optimum combination of strength and
toughness in the welded joint, select a consumable with as low
strength as possible, but which still fulfils the strength requirements for the joint. Using low-strength consumables can offer
several benefits, such as higher toughness of the weld metal,
higher resistance to hydrogen cracking and lower residual
stresses in the joint. Designers should therefore attempt to
Unalloyed or low-alloyed consumables
EN 499 xxx H5
AWS: A 5.18-93 ER70S-6 E7018-1
AWS: A 5.28-79 ER80S-G
Austenitic consumables
EN 1600 E 18 8 Mn
AWS A/SFA 5.4-92 E 307-15
AWS A5.22 E 307 LT-2
OK 48.08, OK Femax 38.65
OK 55.00
OK 67.45
OK 67.52
Filarc 35
Filarc 56 S
Filarc BM 307
OERLIKON
Special
Supercord S
COMET 307
SAFDRY R 307
THYSSEN
Phoenix 120 K
SH Grün K52W
THERMANIT X
OK Autrod 12.51
OK Tubrod 15.00
OK Autrod 16.95
OK Tubrod 14.36
Filarc PZ 6000
Filarc PZ 6130
Filarc PZ 6070
Filarc PZ 6470
OERLIKON
FLUXOFIL 40
Carbofil 100
NERTALIC 51
SAFDUAL 651
THYSSEN
TG 50 B
Union K52
THERMANIT X
Manufacturer
ELECTRODES
ESAB
FILARC
ESAB
WIRES
If consumables are stored in accordance with the manufacturer’s recommendations, the hydrogen content will be maintained at the intended level. This applies, above all, to coated
consumables and fluxes.
FILARC
5
BENDING RECOMMENDATIONS
This section deals with free bending, although roll bending can obviously also be employed. The bending results are dependent on a number of factors which we have grouped under three headings: the plate, the tools
and the procedure. These factors are discussed on page 11, where a couple of examples also are given.
Bending transverse to
the final direction of rolling
Bending line
Grind away any blemishes before
bending. Sheared edges should
also be grinded.
b
Final rolling direction.
The plate identity
is always stamped
transverse to the final
direction of rolling.
R
t
The edges of the die opening should always be as hard as or
harder than the plate being bent, in order to avoid damage to
the die.
To avoid plate surface damage, mill grooves in the die edges and
fit lubricated round rods into the grooves.
The die edge radius should be at least half the plate thickness.
The die opening angle must allow for springback of the plate. As
an example, if Armox 500 shall be bent to an angle of 90°, the die
opening angle should not exceed 70° (see table).
w
Minimum recommended punch radius (R) and die opening width (W) for plate thickness (t) when the plate is bent to 90° parallell to the final rolling
direction and transverse to the final direction of rolling – and also the corresponding springback.
Thickness
[mm]
Transverse
R/t
Parallell
R/t
Transverse
W/t
Parallell
W/t
Springback
[°]
Armox 370T CL1 & CL2
t<8
8-15
>-15
3.0
4.0
5.0
3.5
5.0
6.0
9
10
12
10.5
11
13
9-13
Armox 440
t<8
8-15
>-15
4.0
5.0
6.0
5.0
6.0
7.0
10
10
12
10
12
14
11-18
Armox 500T
t<8
8-15
>-15
5.0
6.0
7.0
5.0
6.0
9.0
10
12
16
12
14
18
12-20
Armox 600T & Advance
Contact SSAB
6
THE PLATE
creased, the bending force and impression marks will admittedly be reduced, but at the expense of increased springback.
Steel grade
Note that the bending force and springback increase with the
plate strength. The top tool radius should also be increased
when increasing the plate hardness.
Note that the opening angle must be so small that it will
allow a sufficient amount of over-bending. Note that in roll
bending, the springback will be much larger than the tabulated values.
Plate surface
Our recommendations apply to shotblasted and anti-corrosion
painted plate. Surface damage and rust which is under tension
during bending may greatly reduce the bendability. In critical
cases, such defects must be ground away.
BENDING PROCEDURE
Friction
The die edges must be clean and undamaged. The bending
force needed and the risk of cracking can be reduced by
using round rods free to rotate as die edges and/or by
lubricating the die edges.
Plate edges
Cut and sheared edges should be deburred and rounded with a
grinder.
Bending angle
Note that the bending angle has less effect on the force
needed and the springback than the die opening width and
steel grade. Springback can be compensated by over-bending
by the same number of degrees.
Plate thickness (t)
As a general rule, thinner plate can be bent to smaller radii.
Final rolling direction
Bending force (P)
The plate can be bent to a smaller radius transverse to the
final rolling direction than bending parallell to the final rolling direction.
The bending force necessary can be estimated using the
formula below. The force is obtained with an accuracy of
±20%, provided that all dimensions used are in mm. For
symbols used, see figure on page 9.
Bend length (b)
If the bend length is less than 10 times the plate thickness,
the plate can often be bent to a smaller radius than the values
given in table below.
P=
P [ton]: Bending force
b [mm]: Bending length
t [mm]: Thickness
Rm [MPa]:Tensile strength
w [mm]: Die opening width
1,6 x b x t2 x Rm
10000 x w
THE TOOLS
Punch radius (R)
If the radius of the punch used for bending is much larger
than that specified in the table on page 9, the force needed
may be higher than the value obtained from the formula, unless the die opening width is increased correspondingly.
Choosing the right punch radius is the most important factor
when bending Armox. A punch radius which is equal to or
somewhat larger than the required bending radius is recommended.
Die opening width (W)
The table (on page 9) specifies the minimum recommended
die opening for minimizing the springback. If the width is in-
Hardness
[HBW]
Tensile strength Rm
[MPa]
Elongation A5
[%]
180
550
28
Armox 370T CL1 & CL2
380-430
1200
11
Armox 440
420-480
1400
10
Armox 500T
480-540
1600
8
S 355 acc to EN10025
Armox 600T
Armox Advance
570-640
2000
7
58-63 HRC
>2000
<7
7
Care should be taken
during all bending – due
to the high strength of the
plate and the high bending
force necessary.
MACHINING RECOMMENDATIONS
Drilling can be performed using high-speed steel drills or cemented carbide drills. When drilling in Armox with
HSS drills in radial/column drilling machines the first choice is a HSS-Co 8% drill with a small helix angle. For
individual holes you can use an ordinary HSS drill.
Advice for reducing vibrations and increasing the drill life length:
•
•
•
•
Minimize the distance between the column and the drill
as well as the drill tip and the workpiece
Don´t use longer drill than necessary
Always use metal supports
Clamp securely
•
•
•
Solid and firm table
Use coolant
Just before the break through, disengage the feed rate
for about a second and re-engage when the play and/or
springback have ceased to avoid snapping the drill tip.
HSS-drill
Armox 370T CL1 & CL2
Armox 440T
Armox 500T
~9
~7
~5
VC [m/min]
DC [mm]
Feed rate [mm/rev] and speed [RPM]
5
0.05 / 575
0.05 / 445
0.05 / 320
10
0.10 / 285
0.09 / 220
0.08 / 130
20
0.23 / 145
0.20 / 110
0.18 / 65
30
0.35 / 95
0.30 / 75
0.25 / 45
DRILLING RECOMMENDATIONS WHEN THE MACHINE CONDITIONS ARE GOOD
Solid cemented carbide drill
Cutting speed. VC [m/min]
Feed rate, fn [mm/rev]
Armox 370T CL1 & CL2
Armox 440T
Armox 500T
Armox 600T
Armox Advance
35 - 45
30 - 40
25 - 35
20 - 30
-
0.1 - 0.15
0.1 - 0.15
0.08 - 0.12
0.06 - 0.1
-
Brazed cemented carbide drill
Cutting speed, VC [m/min]
Feed rate, fn [mm/rev]
Armox 370T
CL1 & CL2
Armox 440T
Armox 500T
Armox 600T
Armox Advance
35 - 45
30 - 40
20 - 30
20 - 30
-
0.10 - 0.15
0.1 - 0.15
0.08 - 0.12
0.07 - 0.12
-
Indexable insert drill
Cutting speed, VC [m/min]
Feed rate, fn [mm/rev]
Armox 370T
CL1 & CL2
Armox 440T
Armox 500T
Armox 600T
Armox Advance
60 - 80
50 - 70
40 - 60
30 - 40
-
0.06 - 0.14
0.06 - 0.14
0.06 - 0.12
0.05 - 0.1
-
8
COUNTERSINKING & COUNTERBORING
Countersinking/boring are best performed using tools which have replaceable inserts.
Always use a revolving pilot and use coolant.
Armox 370T
CL1 & CL2
Armox 440T
Armox 500T
Armox 600T
Armox Advance
VC [m/min]
25 - 70
20 - 50
17 - 50
12 - 40
-
Feed rate [mm/rev]
0.10-0.20
0.10-0.20
0.10-0.20
0.10-0.20
-
DC [mm]
Speed [RPM]
19
420-1175
335-840
285-840
201-670
-
24
330-930
265-665
225-665
151-531
-
34
235-655
185-470
160-470
112-375
-
42
190-530
150-380
130-380
91-303
-
57
140-390
110-280
95-280
67-223
-
* Reduce the cutting data with about 30 % in countersinking.
TAPPING
With use of correct tools all tapping/thread milling can be performed in all Armox grades. We
recommend four-flute taps which can withstand very high torque which occurs during tapping in
hard materials. If the available force is not critical, the drilled hole can be 3% larger than standard,
that will increase the lifetime of the tap.
Tap for blind
holes.
VC [m/min]
Armox 370T
CL1 & CL2
Armox 440T
Armox 500T
Armox 600T
Armox
Advance
~5
~3
~ 2.5
~
~
DC [mm]
M5
Tap for through
holes.
Feed rate [mm/rev] and speed [RPM]
320
190
160
-
-
M10
160
95
80
-
-
M16
100
60
50
-
-
M20
80
50
40
-
-
M24
65
40
30
-
-
M30
55
30
25
-
-
Armox 370T
CL1 & CL2
Armox 440T
Armox 500T
Armox 600T
Armox
Advance
THREAD MILLING
Cutting speed Vc [m/min] and feed rate [mm/rev]
VC
~ 50
~ 40
~ 30
~ 30
-
fn
0.05
0.04
0.03
0.03
-
* To manage thread milling, a CNC machine with minimum 3-axis is necessary and the thread should be made in two passes.
9
MILLING
To ensure rational production, milling cutters with cemented carbide inserts are recommended.
FACE MILLING
Coated CC
Cermet
Coated CC
Grade
P40 / C5
P25 / C6
P20 / C6-C7
K20 / C2
Conditions
unstable
average
stable
stable
0.1-0.2-0.3
0.1-0.2-0.3
0.1-0.2
0.07-0.12
Feed rate [fz]
Cutting speed, VC [m/min]
Armox 370T
CL1 & CL2
-
150-120-110
150-120
-
Armox 440T
-
150-120-110
150-120
-
Armox 500T
-
120-100
120-100
-
Armox 500T
-
120-100
120-100
-
Armox 600T
-
-
* 80-70
80-70
Armox Advance
-
-
* 80-70
80-70
* fz recommendation 0.07-0.12
Keep this in mind:
•
Position the cutter off-centre (as fig. to the left) to achive a
thicker chip at the entry and to avoid thick chip on the exit.
Centering the cutter (as fig. to the right) might also cause
vibrations.
• Cutter diameter should be 20%-50% larger than the width
of cut, ae.
• Always use down milling.
HSS-Co
Grade
Conditions
Feed rate [fz]
CC
TiCN
K10 / C3
K10 / C3
coated
uncoated
coated
insert
unstable
stable
stable
stable
0.02-0.10
0.02-0.20
0.05-0.15
0.03-0.09
P10 / C7
Cutting speed. Vc [m/min]
Armox 370T
CL1 & CL2
18
90
100
110-90
Armox 440T
18
90
100
110-90
Armox 500T
-
50
80
90-70
Armox 600
-
-
-
-
Armox Advance
-
-
-
-
10
SSAB has employees in over 45 countries and operates production facilities
in Sweden and the US. SSAB is listed on the NASDAQ OMX Nordic Exchange,
Stockholm. www.ssab.com.
SSAB
Klarabergsviadukten 70, D6
SE- 101 21 Stockholm, Sweden
Telephone:+46 (8) 45 45 700
Email:[email protected]
www.armoxplate.com
701-UK-Armox: WORKSHOP RECOMENDATIONS-V2-2011. Halledo. Österbergs & Sörmlandstryck.
SSAB is a global leader in value added, high strength steel. SSAB offers products
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and more sustainable world.