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Workshop Recommendations

This leaflet contains general suggestions and calculation models. SSAB does hereby ex-pressly 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

3

CUTTING RECOMMENDATIONSProtection 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.

ABRASIVE WATERJETThis process can be applied to the com-plete range of high-hardness Armox plate, and is recommended as the best method, because the absence of HAZ eliminates the risk of cracking.

LASER CUTTINGHigh-hardness Armox plate up to around 20 mm thickness can be cut using this process. It generates a narrow kerf, usu-ally less than 1 mm, and a narrow HAZ, usually less than 3 mm.

PLASMA CUTTINGHigh-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 cut-ting can be performed under water, which minimizes the amount of distortion.

Armox 370T CL1 & CL2

Armox 440 Armox 500T Armox 600T Armox Advance Recommended cutting method

Up to 15 mm Up to 25 mm Up to 15 mm Up to 10 mm -

• Abrasive waterjet

• Plasma

• Laser

• Abrasive disc

15 - 25 mm 25 - 35 mm 15 - 25 mm 10 -20 mm -


• Laser

• Gas cutting at reduced speed

• Gas cutting plus preheating to 170 + 30°C

• Abrasive disc

40 - 60 mm 25 - 35 mm 40 - 60 mm 20 - 30 mm -


• Gas cutting plus preheating to 170 + 30°C

plus keep warm for 4 hours at 160 + 40°C

• Abrasive disc

Above 60 mm Above 35 mm Above 60 mm Above 30 mm Up to 7 mm• Abrasive waterjet

• Abrasive disc

-

-

-

GAS CUTTINGThis process can be applied to high-hard-ness 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.

Uncontrolled gas cutting of high-hard-ness 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 crack-sensitivity.

The most effective technique to avoid cracking during and af-ter 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.

ABRASIVE DISCThis 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.

4

WELDING RECOMMENDATIONSSSAB 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.

EDGE PREPARATIONA good fit between the work pieces is essential to minimize stresses and thereby the risk of cracking. All types of impuri-ties on and near the edges, such as mill scale, rust, oil, paint and moisture, should be removed before welding.

TACK WELDINGDuring 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.

PREHEAT TEMPERARATURES 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.

If unalloyed or low-alloyed consumables are used preheating is necessary and dependent on plate thickness and restraint con-ditions.

1) Carbon equivalent (CEV) in accordance to IIW:

2) For plate thicknesses >80 mm, please contact SSAB

Steel grade Thickness range Carbon equivalent1


3–150 mm 0.67–0.75 2

Armox 440T 4–30 mm 0.68–0.72

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

C + + + Mn6

Cu + Ni15

Cr + Mo + V5

Minimum recommended preheat and interpass temperatures for different plate thicknesses (mm)

Maximum recommended preheat/interpass temperatures

3 10 20 30 40 50 60 70 80 140 150

Armox 370 T Class 1Armox 370 T Class 2

Armox 440 T

Armox 500 T

Armox 600 T

Armox Advance

Armox 370 TArmox 370 T Class 2

Armox 440 T

Armox 500 T

Armox 600 T

Armox Advance

400°C

200°C

200°C

180°C

150°C

Thickness

3-80 mm3-150 mm

4-30 mm

3-140 mm

4-20 mm

5-7 mm

100°C

125°C

125°C

125°C

150°C

150°C

150°C

175°C

175°C

200°C

200°C

100°C + austenitic

100°C + austenitic

50°C75°C

100°C + austenitic

Measure the preheat temperature here

75 mm

Intended weld joint

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, mea-sure the temperature after 1 minute, etc. The interpass temperature can be measu-red in the weld metal or in the immediately adjacent parent metal.

The temperature should be maintained throughout the entire weld operation, tack welding and root passes included.

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.

5

Manufacturer

Unalloyed or low-alloyed consumablesEN 499 xxx H5AWS: A 5.18-93 ER70S-6 E7018-1AWS: A 5.28-79 ER80S-G

Austenitic consumablesEN 1600 E 18 8 MnAWS A/SFA 5.4-92 E 307-15AWS A5.22 E 307 LT-2

ELEC

TRO

DES

ESAB OK 48.08, OK Femax 38.65OK 55.00

OK 67.45OK 67.52

FILARC Filarc 35Filarc 56 S Filarc BM 307

OERLIKON SpecialSupercord S

COMET 307SAFDRY R 307

THYSSEN Phoenix 120 KSH Grün K52W THERMANIT X

WIR

ES

ESAB OK Autrod 12.51OK Tubrod 15.00

OK Autrod 16.95OK Tubrod 14.36

FILARC Filarc PZ 6000Filarc PZ 6130

Filarc PZ 6070Filarc PZ 6470

OERLIKON FLUXOFIL 40Carbofil 100

NERTALIC 51SAFDUAL 651

THYSSEN TG 50 BUnion K52 THERMANIT X

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 tempera-tures for heat inputs lower than 1.0 kJ /mm can be determined by an applicable standard for high strength steels. One exam-ple 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.

CHOICE AND HANDLING OF CONSUMABLESConsumables 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 require-ments 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

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.

The hydrogen content should be lower than or equal to 5 ml of hydrogen per 100 g of weld metal when welding with unal-loyed 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.

If consumables are stored in accordance with the manufac-turer’s recommendations, the hydrogen content will be main-tained at the intended level. This applies, above all, to coated consumables and fluxes.

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.

6

Bending line

Bending transverse to the final direction of rolling

Grind away any blemishes before bending. Sheared edges should also be grinded.

Final rolling direction. The plate identity is always stamped transverse to the final direction of rolling.

t

w

b

R

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]

TransverseR/t

ParallellR/t

TransverseW/t

ParallellW/t

Springback[°]

Armox 370T CL1 & CL2t<8

8-15>-15

3.04.05.0

3.55.06.0

91012

10.51113

9-13

Armox 440t<8

8-15>-15

4.05.06.0

5.06.07.0

101012

101214

11-18

Armox 500Tt<8

8-15>-15

5.06.07.0

5.06.09.0

101216

121418

12-20

Armox 600T & Advance Contact SSAB

BENDING RECOMMENDATIONSThis section deals with free bending, although roll bending can obviously also be employed. The bending re-sults 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.

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).

7

THE PLATE

Steel gradeNote that the bending force and springback increase with the plate strength. The top tool radius should also be increased when increasing the plate hardness.

Plate surfaceOur 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.

Plate edgesCut and sheared edges should be deburred and rounded with a grinder.

Plate thickness (t)As a general rule, thinner plate can be bent to smaller radii.

Final rolling directionThe plate can be bent to a smaller radius transverse to the final rolling direction than bending parallell to the final roll-ing direction.

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.

THE TOOLS

Punch radius (R)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 recom-mended.

Die opening width (W)The table (on page 9) specifies the minimum recommended die opening for minimizing the springback. If the width is in-

Care should be taken during all bending – due to the high strength of the plate and the high bending force necessary.

Hardness[HBW]

Tensile strength Rm[MPa]

Elongation A5[%]

S 355 acc to EN10025 180 550 28

Armox 370T CL1 & CL2 380-430 1200 11

Armox 440 420-480 1400 10

Armox 500T 480-540 1600 8

Armox 600T 570-640 2000 7

Armox Advance 58-63 HRC >2000 <7

creased, the bending force and impression marks will admit-tedly be reduced, but at the expense of increased springback.

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 tabu-lated values.

BENDING PROCEDURE

FrictionThe 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.

Bending angleNote 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.

Bending force (P)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.

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, un-less the die opening width is increased correspondingly.

P =1,6 x b x t2 x Rm

10000 x w

P [ton]: Bending forceb [mm]: Bending lengtht [mm]: ThicknessRm [MPa]: Tensile strengthw [mm]: Die opening width

8

MACHINING RECOMMENDATIONSDrilling 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:

HSS-drill

• Minimizethedistancebetweenthecolumnandthedrill as well as the drill tip and the workpiece• Don´tuselongerdrillthannecessary• Alwaysusemetalsupports• Clampsecurely

• Solidandfirmtable• Usecoolant• Justbeforethebreakthrough,disengagethefeedrate for about a second and re-engage when the play and/or springback have ceased to avoid snapping the drill tip.

Armox 370T CL1 & CL2 Armox 440T Armox 500T

VC [m/min] ~ 9 ~ 7 ~ 5

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

Armox 370T CL1 & CL2 Armox 440T Armox 500T Armox 600T Armox Advance

Cutting speed. VC [m/min] 35 - 45 30 - 40 25 - 35 20 - 30 -

Feed rate, fn [mm/rev] 0.1 - 0.15 0.1 - 0.15 0.08 - 0.12 0.06 - 0.1 -

Brazed cemented carbide drill

Indexable insert drill


Armox 440T Armox 500T Armox 600T Armox Advance

Cutting speed, VC [m/min] 35 - 45 30 - 40 20 - 30 20 - 30 -




Cutting speed, VC [m/min] 60 - 80 50 - 70 40 - 60 30 - 40 -


9

COUNTERSINKING & COUNTERBORING

Countersinking/boring are best performed using tools which have replaceable inserts. Always use a revolving pilot and use coolant.

* Reduce the cutting data with about 30 % in countersinking.

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 -

TAPPING

THREAD MILLING

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.

* To manage thread milling, a CNC machine with minimum 3-axis is necessary and the thread should be made in two passes.

Armox 370T CL1 & CL2 Armox 440T Armox 500T Armox 600T Armox

Advance

VC [m/min] ~ 5 ~ 3 ~ 2.5 ~ ~

DC [mm] Feed rate [mm/rev] and speed [RPM]

M 5 320 190 160 - -

M10 160 95 80 - -

M16 100 60 50 - -

M20 80 50 40 - -

M24 65 40 30 - -

M30 55 30 25 - -



Cutting speed Vc [m/min] and feed rate [mm/rev]

VC ~ 50 ~ 40 ~ 30 ~ 30 -

fn 0.05 0.04 0.03 0.03 -

Tap for blind holes.

Tap for through holes.

10

MILLING

To ensure rational production, milling cutters with cemented carbide inserts are recommended.

* fz recommendation 0.07-0.12

FACE MILLING

Coated CC Cermet Coated CC

Grade P40 / C5 P25 / C6 P20 / C6-C7 K20 / C2

Conditions unstable average stable stable

Feed rate [fz] 0.1-0.2-0.3 0.1-0.2-0.3 0.1-0.2 0.07-0.12

Cutting speed, VC [m/min]


- 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

Keep this in mind:

• Positionthecutteroff-centre(asfig.totheleft)toachivea 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.

•Cutterdiametershouldbe20%-50%largerthanthewidth of cut, ae.

•Alwaysusedownmilling.

HSS-Co CC

Grade TiCN K10 / C3 K10 / C3 P10 / C7

coated uncoated coated insert

Conditions unstable stable stable stable

Feed rate [fz] 0.03-0.09 0.02-0.10 0.02-0.20 0.05-0.15

Cutting speed. Vc [m/min]


18 90 100 110-90

Armox 440T 18 90 100 110-90

Armox 500T - 50 80 90-70

Armox 600 - - - -

Armox Advance - - - -

SSABKlarabergsviadukten 70, D6

SE- 101 21 Stockholm, Sweden

Telephone:+46 (8) 45 45 700

Email:[email protected]

www.armoxplate.com

SSAB is a global leader in value added, high strength steel. SSAB offers products developed in close cooperation with its customers to create a stronger, lighter and more sustainable world.

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.

701-U

K-Armox: W

OR

KSHO

P RECO

MEN

DATIO

NS-V2-20

11. Halledo. Ö

sterbergs & Sörmlandstryck.

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