og y . ir hno l t e c m en · PDF fileLOESCHE MILL Comparison life time after 4000 h Ni-Hard 4With VAUTID 100 cement technology magazine: 021-22883306, 22861343 www

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cement technology magazine: 021-22883306, 22861343

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STEPS TO HARDFACE SUCCESSFULLY

Dr. H. Riegger



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RCoal mill



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LOESCHE MILL Comparison life time after 4000 h

Ni-Hard 4 With VAUTID 100



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RMicrostructure Wear Resistance Castings



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RTypical microstructure VAUTID 100



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VAUTIDf i g h t s w e a r

RWELDING PROCESS

Standard welding processfor difficil welding materials

Welding process for rollers

Normaly procedure

Clean weld areaPreheat alloy steels to 250°CHigh carbon steels 300-400°CUse short arc lengthPeen whilst still hot, slow coolOn ferritc and martensitic steelsdeposit a buttering layer CrNi 29/9On alloy and carbon steels Ni-Base

Procedure for rollers

Clean weld areaPreheat only 70 - 80°CWelding speed >1m/minCooling with compressed airInterpasstemperature <140°CHeat input 4800 J/cmCross check every 10-12 mm



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RBASE MATERIALS OF THE ROLLERS

Steel casting

Cast ironGGGGGL

Chromium casting

Ni-Hard alloys



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VAUTIDR

f i g h t s w e a r

System Fe-Cr-C at 1000°Caccording to K.Bungardt, E. Kunze and E. Horn

0,5 1,0 1,5 2,0 2,5 3,0 3,5 %C

35

30

25

20

15

10

5

%Cr

γ+Kcγ

α… Ferrit

α

γ…. Austenit

K1.. M23 C6K2.. M7 C3Kc.. M3 C

α+K1

α+γγ+K2



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Ni Cr C Si MnNi-Hard 1ASTM A53 I A

3.3 - 5.0 1.4 - 4.0 3.0 – 3.6 0.8 max 1.3 max

Ni-Hard 2ASTM A53 I B

3.3 - 5.0 1.4 - 4.0 2.9 max. 0.8 max 1.3 max

Ni-Hard 3ASTM A53 I C

2.7 - 4.0 1.1 - 5.0 2.9 – 3.7 0.8 max 1.3 max

Ni-Hard 4ASTM A53 I D

5.0 - 7.0 7.0 - 11.0 2.5 – 3.6 1.0 – 2.2 1.3 max

Ni-Hard alloys



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RDelivery of used bandages



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RPROCEDURE FOR NIHARD ROLLERS

Before welding, the rollers are connected to a turning device or lathe since the procedureshould be performed in automatic mode according to the following steps.



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1. Visual inspection of the parts to determine the degree of the wear. Maximum surfacing to an area 50 mm diameter is recommended.Parts with deep fractures (over 30 mm) should not be surfaced. Analysis with penetrating liquids is required for this initial inspection.



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Inspection using dye penetrants to ensurethat no cracks are in the material



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RVisual inspection



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2. Once the possible small cracks and chips have been located, these should be removed by grinding, never by air arc gouging to avoid crack propagation by thermal stresses. The edges of the part should also be rounded off.



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3. Pre-heating to approximately 70/80°C. This pre-heating must be done slowly and thoroughly, with the help of propane burners. The temperature must be controlled throughout the entire process so that the surface temperature of the part never exceeds 140°C.



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4. Positioning of the welding torch and the cooling air nozzle. Adjust the welding nozzle stick-out, the air nozzle clearance and the position of both in relation to the vertical axis of the part.



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RPOSITIONING FOR WELDING



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NozzleAir

POSITIONING FOR WELDING



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5. With the part rotating and the air flow open, continuous welding with VAUTID 100 can begin. Recommended rotation and feed parameters should be respected.



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RWELDING PARAMETERSSCHWEISSEINSTELLUNG

First layer following layersWelding product VAUTID 100 Ø 2,80 mmCurrent [A] 350 350 - 450(Stromstärke)Voltage [V] 30 30 – 38(Spannung)Stick out [mm] 30 – 35 30 - 35(Freies Drahtende)Weld speed [cm/min] 100 120 (Schweissgeschw.)Interpass temperature [°C] max. 140(Zwischenlagentemperatur)



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RHeat InputStreckenenergie

Schweissstrom I [A] 400Schweissspannung U [V] 30Wärmeeinwirkungsgrad [n] 0,8Schweissgeschwindigkeit [v] [cm/sec] 2 120

9600[J/cm] 4800

U*I*nvES = [J/cm]



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RHardfacing of a roller for a

cement plant



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6. To prevent localised overheating, the welding position can be changed at times. This step must be taken if the maximum temperature of 140°C cannot be respected in the welding area.



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7. It is important to match the original roller contour in the initial resurfacing run, in order to subsequently obtain layer by layer a final appearance as regular as possible and near to the finish size required within a reasonable tolerance (3/4 mm), as a final machining operation is unfeasible.



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RControl the finish size



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8. After slow cooling protected from air currents, the part is ready for service.



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Documents

og y . ir hno l t e c m en · PDF fileLOESCHE MILL Comparison life time after 4000 h Ni-Hard 4With VAUTID 100 cement technology magazine: 021-22883306, 22861343 www