Mechanical descaling by high pressure water jet assoc.prof. Michal - - PowerPoint PPT Presentation

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Mechanical descaling by high pressure water jet assoc.prof. Michal - - PowerPoint PPT Presentation

Jun 03, 2023 439 likes •747 views

Mechanical descaling by high pressure water jet assoc.prof. Michal Pohanka Workshop on Pickling Solutions Technology 13th of November 2019, Dsseldorf Introduction Brno University of Technology, Czech Republic Hydraulic descaling of

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assoc.prof. Michal Pohanka

Mechanical descaling by high pressure water jet

Workshop on Pickling Solutions Technology 13th of November 2019, Düsseldorf

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www.heatlab.cz

Introduction

 Brno University of Technology, Czech Republic  Hydraulic descaling of coils of wires  Laboratory experiments

Impact pressure distribution measurement

Hydraulic descaling

EDX Analysis with a Scanning Electron Microscope

 Conclusion

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www.heatlab.cz

Brno, Czech Republic

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www.heatlab.cz

Brno University of Technology

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www.heatlab.cz

Faculty of Mechanical Engineering

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Secondary Cooling

Continuous Casting

Descaling Roll Cooling Product Cooling

Rolling and heat treatment Experimental research of heat transfer and heat treatment Numerical models of continuous casting, rolling and heat treatment

Contact

Heat Transfer and Fluid Flow Laboratory

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www.heatlab.cz

Descaling of coils of wires – outer diameter 1.4 m

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Impact pressure distribution measurement

DAQ PC Nozzle Impact area Pressure Sensor Moving Plate

Pressure Position

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Spray comparison – High and low pressure but same water flow rate

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Spray comparison – High and low pressure but same water flow rate

Video

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Distance 300 mm - No wires Nozzle A at 45 MPa Catalogue spray angle 45°

kPa 1 2 3 4 5 6.3 kPa 0.03 0.5 1 1.5 2 2.5 3 3.5 3.87

220 200

Nozzle B at 5 MPa Catalogue spray angle 40°

kPa 0.03 0.5 1 1.5 2 2.5 3 3.5 3.87 kPa 1 2 3 4 5 6.3

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2 4 6 8 10 12 14 200 mm 300 mm Impact pressure [kPa] Nozzle A Nozzle B

Impact pressure measurements without dummy wires

5MPa 45MPa 100% 92% 100% 79% Spraying distance 5MPa 45MPa

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Cleaning graphite coating

Nozzle A at 45 MPa Nozzle B at 5 MPa

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Cleaning graphite coating - Video

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Impact pressure distribution while spraying through wires

1 layer 6 layers

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One layer of wires

3.

5MPa 45MPa

6

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Distance 300 mm - with 6 layers of wires – 5 MPa

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Distance 300 mm - with 1-6 layers of wires – smaller nozzle, 45 MPa 1 layer 2 layers 4 layers 6 layers

kPa 0.2 0.4 0.6 0.8 1 1.2 1.4 kPa 0.2 0.4 0.6 0.8 1 1.2 1.4 kPa 0.2 0.4 0.6 0.8 1 1.2 1.4 kPa 0.2 0.4 0.6 0.8 1 1.2 1.4

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Distance 300 mm - with 1-6 layers of wires - Video

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Spray distances during hydraulic descaling 200 200

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Distance of descaling header from wires is 200 mm

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Reduced spray angle Spray angle 45° Spray angle 30°

kPa 0.03 0.5 1 1.5 2 2.5 3 3.5 3.87 kPa 1 2 3 4 5 6 6.7

200 110

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Hydraulic descaling Wire descaling using smaller nozzle at 45 MPa for steel grade 1.4571

* This is not the final surface of the product. This is surface during pickling program.

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EDX Analysis with a Scanning Electron Microscope

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EDX Analysis with a Scanning Electron Microscope

backscattered (BSE) secondary electrons (SE)

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EDX Analysis with a Scanning Electron Microscope

Element Wt % Inte. Error O 27.8 1.4 Si 0.4 16.0 MoL 3.9 4.7 Cr 32.2 1.0 Mn 0.3 29.4 Fe 31.3 1.3 Ni 4.0 5.3

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EDX Analysis with a Scanning Electron Microscope

Steel grade 1.4404

Fe Cr Ni Mo Mn Si Data sheet 16.5–18.5% 10–13% 2–2.5% ≤ 2% ≤ 1% Measured 66.4% 17.6% 11.1% 2.9% 1.3% 0.8%

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EDX Analysis with a Scanning Electron Microscope

Scale layer on 1.4404

Fe O Cr Ni Mo Mn Measured 31.3% 27.8% 32.2% 4.0% 3.9% 1.3%

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EDX Analysis with a Scanning Electron Microscope

Scale layer on 1.4404

Fe O Cr Ni Mo Measured 32.7% 20.8% 28.7% 13.5% 4.0%

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Conclusion Thank you for your attention… www.heatlab.cz

 Big spraying distance (200 mm and more)

 Free space

 Use bigger nozzle and smaller pressure

 Spraying through wires

 Use smaller nozzle and bigger pressure

 Hydraulic descaling is effective during pickling.