It Nardoni Analysis Rt840

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I & TNardoniInstitute

Brescia

ANALISI METALLURGICHE ITALY

I&T Nardoni Institute ATB RivaCalzoni-Brescia

Hardness and metallographic replicas on hardened steel S690QL EN 10204 ofbifurcation septum for project ALSTOM CV2.LEDI

Technical Report nr. 840 - July 2012

SCOPE

Investigation on localized overheating alteration erroneously performed on bifurcation sickleMK. 206For additional information see ATB NCR 12-068 rev.1

REFERENCE

ATB NCR 12-068 rev.01EN 10025-6

MODE

On the overheating area has been drawing a reference grid (pict.1) in order to define testposition.Hardness checks have been performed to established the heat altered area.On Altered and Unaltered area metallographic replicas have been performed.After the test mentioned above, on area O3 two (2) mm in thk. have been removed bygrinding in order to define how deep is the altered metal.

After grinding the above mentioned area, new hardness tests and new replicas have beenperformed.Hardness test have been evaluated in HB by EQUOTIP in correct status of calibration as perProc. Block calibration nr.D.1571.0138BReflective metallographic Replica have been performed.As shown in the picture, all the area involved in the test have been adequately prepared.

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Hardness and replica positions overview: O3-L2-E5-Y7-Y8- P1-P2( picture 1)

TEST RESULTS

HARDNESS RESULTS

Replica nr HB EQUOTIP Note

O3-1 341-346 On heating zone (dark area in photo)O3-1 224 No overheated zone (clear area in photo)

L2 326-341 On heating zone (dark area in photo)

L2 230 HAZ of heating area.

L2 189-186 Unaltered bese material

E5 266 Unaltered bese material

Y7 214-213 Unaltered bese material out of reference grid

Y8 248-254 Unaltered bese material out of reference grid

O3-2 228 On heating zone after removal by grinding of about 2 mm in Thickness.

O3-2 350-370 On heating zone after removal by grinding of about 1 mm in Thickness.

P1 233 At thk. in the plate thickness

P2 178 At thk. in the plate thickness

REPLICAS RESULTS

Areas with overheating showed a microstructural refinement without precipitation of brittlephases; this confirms detected Hardness.A limited removal (ref. position O3) also showed that the area of overheating is only relatedto the surface and subsurface section of the plateAs in photo relevant O3-2 the area where 2mm have been removed doesnt show heatingalteration after etching.

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Location and identification replica after etching (Nital 4%)

O3-1 replica position: heating area (dark zone) L2 replica position: heating area (dark zone)

E5 replica position Y7 replica position

Y8 replica position 03-2 replica position after further removal of about 2 mm:important improving of clear area (no overheated)

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Micrographic replica examination

Replica position: O3-1

100x

heating zone

fine structure


500x

heating zone

Structure: bainite

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Replica position: 03-1

100x

HAZ (heat affected zone)


100x

No overheated zone (clear area)

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500x

No overheated zone (clear area)

Structure: bainite

Replica position: O3-2(after removal of about 2 mm)

100x

heating zone

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Replica position: 03-2(after removal of about 2 mm)

500x

heating zone

Structure: bainite


(after removal of about 2 mm)

100x



(after removal of about 2 mm)

100x

Light area (no overheating)

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Replica position: O3-2(after removal of about 2 mm)

500x

Light area (no overheating)

Structure: bainite

Replica position: L2

100x

heating zone


500x

heating zone

Structure: bainite

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100x


Replica position: E5100x

Reference grid: out ofoverheating area

Typical plate surfacemicrostructure with ferrite

Replica position: E5500x

Reference grid: out ofoverheating area


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Replica position: Y7100x

Outside reference grid, no

overheating area



Outside reference grid, nooverheating area




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It Nardoni Analysis Rt840