Monitoring Defect Levels in Steel During the Manufacturing

Process.

Iain Baillie

Mentors: Kevin Neailey (WMG)

Steve Dixon (Physics)

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Contents

• Problem Definition

• Objectives

• Methodology

• Innovations

• The EngD Competences

• Conclusions

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Slab Casting Process Overview

LadleLadleTurret

Tundish

SlabMould

SprayChamber

TorchCutter

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Slabs, Blooms & Billets

Slab

2030 x 305 mm

Bloom

755 x 385 mm

Billet

180 mm2

Product length is approximately 6 to 12m

Some Typical Casting Defects

TransverseCracks

Corner Cracks

Pinholes

Longitudinal Mid-Face Cracks

Star Cracks

Sub-Surface Porosity

Inter ColumnarCracking Centreline

SegregationSpider Cracks

Off-Corner Cracks

LongitudinalCorner Cracks

Edge Cracks/Splits

Plus Scale & Oscillation Marks

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Why Use Laser-EMATs?• Give ‘real time’ feedback to concast

operators.• Be used to guarantee product quality and

suitability for downstream Corus & External customers.

• Reduce the amount of scarfing (yield losses etc).

• Minimise “eye-ball” inspection.• Could be linked into plant “quality tracking”

software.• Validate models.• Size products.• Ensure no molten core!

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How to Measure Defects?

• Need to consider the environment of a continuous casting plant; e.g. harsh, hot, dusty, machine vibrations.

• No “off the shelf” product exists.• It would be beneficial if both surface

defects and internal defects could be found.

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The Selection of the Optimal Technique.

• Advice was gathered from Corus research scientists and from steel plant technical personnel. No ‘off-the-shelf’ technique was available

• A review of the literature was conducted to assess all the various options available that had the potential for use for continuous casting.

• The Laser-EMAT technique was found to be the most viable one, but would require significant refinement to reach the prototype stage.

•Laser-EMATs use ultrasonics; and can therefore be used to find both surface and internal defects.

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Laser-EMATs

An EMAT is an “ElectroMagnetic Acoustic Transducer”.

It does not need any gel or water coupling as it is electromagnetically coupled. The EMAT can be positioned a few millimetres above the surface of the hot steel.

Laser generates ultrasoundEMAT probes can be used to detect it.

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What Happens When the Laser Hits?

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Fundamental Ultrasonics

The laser generates the ultrasound

The EMAT detects the ultrasound

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Laboratory Trials

Moving steel (at room temperature)

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Trolley Based Inspection

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LASEREMAT

x

x

LASEREMAT

LASEREMAT

x

Slot

Slot

Slot

Side view of billet being inspected

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Case 3

Case 1

Case 2*

Moving The Steel in 2mm increments

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Moving The Steel at Constant Velocity

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Laboratory & Pilot Trials

Experiments to ensure EMATs work efficiently at high

temperatures.

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Water-Cooled EMAT

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Water-Cooled EMAT

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Pilot Scale Trials

Moving steel (at room temperature)

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Cold Inspection on TTC Rolling Mill

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Defect

Results from cold tests on the rolling mill

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Pilot Scale Trials

Moving steel (at 800°C)

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Hot Inspection on Blue Bay Rolling Mill

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Results from the hot test on the rolling mill - 800°C.

Defect/(Arbitrary units)

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Caster Installation

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The EngD Competences• Expert Knowledge of an Engineering Area

– Continuous Casting Process– Laser & EMAT ultrasonics– Software control and data acquisition via LabVIEW software

• The appreciation of engineering and development culture– Working closely with research group within Physics Dept at

Warwick and at R,D&T with Corus. Able to work and communicate at all levels to explain aims and objectives.

– MSc Modules in this area taken.• Project and Programme Management Skills

– Wrote EU proposal (RFCS)– Project leader and coordinator for the RFCS project (1M Euro) – a

multi-national collaboration with other steel companies for inspection techniques.

– MSc Modules in this area taken.

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The EngD Competences 2• Teamwork and Leadership

– I work in a matrix R,D&T organisation, and lead the Laser-EMAT project (which I am also the project champion for)

– MSc Modules in this area taken.• Oral and Written Communication Skills

– Have presented the Laser-EMAT work to EU conferences; specifically for general steel & management audiences, dedicated casting conferences and for dedicated NDT conferences. Winner of IOM3 Lecture Competition.

• Technical Organisation Skills– Have managed to achieve project objectives; good design processes of

equipment, software interpretation & modelling, software design, practical engineering & instrumentation experience.

– MSc Modules in this area taken.• Financial project planning and control

– Have controlled project spending (hours spent, capital expenditure, sub-contractors, component purchases, EU exchange rates and coordinated EU partners forms for the project proposal and mid-term financial reporting)

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The EngD Competences 3• Ability to apply skills in new and unusual

situations– The casting process is somewhat unique in terms of industrial

‘robustness’.– Laser-EMAT technique very much the ‘cutting edge’

• Ability to seek optimal, viable solutions for complex engineering problems and to seek out relevant information sources.– Have met with many of the experts in casting, NDT and laser-

EMAT fields.– Conferences– Have produced two in-depth literature reviews– Have worked hard to ensure prototypes are ‘right first time’

and to ensure the experimental research is as rigorous as possible.

– MSc Modules in this area taken.

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Conclusions• EMAT probes have been optimised and water-

cooled. They can measure ultrasonic waves at temperatures in excess of 1000°C.

• A trolley based system has been made that can test steel samples easily, with a high degree of automation.

• Software has been designed to control the laser, trolley system and to acquire the ultrasonic data.

• For the first time in the world, Laser-EMAT inspection has revealed a defect in hot (800°C), as-cast steel.

• An enhanced Pilot Plant is due to be finished at Corus shortly and the Laser-EMAT prototype can be tested on this.