7/28/2019 Cracking Perception by Emitted Sound During Quenching

1/3

9/27/2011

1

JournalAuthors:FrancRAVNIKandJanez GRUM

Presentedby:GlennGilTamayo

ForCE297 NonDestructiveTesting

INTRODUCTION ThepaperpresentsaNonDestructiveTestMethod

usingACOUSTICEMISSIONduringQUENCHINGProcess.

QUENCHING QUENCHINGPROCESS 1.HEATINGTHEMETAL

Heatingofthematerialtotherequiredtemperature(815900C)

Soakingcanbedonebyair(airfurnace)orliquid(bath)

2.WETTINGPROCESS

Materialis

immediately

plunged

in

liquid

media e.g.

air,

brine,waterandoil

THISRESULTSINANEXTREMELYHARDBUTBRITTLEMATERIAL.

DURINGTHEWETTINGPROCESS Formationofbubbles,whichoscillatesandeventually

disappearintheliquid.

Thisprocessgeneratenoise.

Theseemittedsoundsignalsaredetectedandanalyzedtoprovideusefulinformationduringthequenchingprocess.

EXPERIMENTALSETUP

7/28/2019 Cracking Perception by Emitted Sound During Quenching

2/3

9/27/2011

2

SPECIMENMATERIALANDFORM LowalloyCrMoheat

treatablesteel(EN42CrMo4)

Thisformischosentoachievecrackingofthespecimenduringthequenchingprocess

QUENCHINGMEDIAPUREWATER SALTSOLUTION Toensurepropermodeof

quenching Toensurehighercoolingrate

thanthecriticalcoolingrate

Ahighercoolingratewillcausethespecimentocrackaxially

PROCEDURE Preheatingto~600C

Progressiveheatingto600C

Theinitialquenchingmediumtemperatureis18C

Thefinalquenchingmediumtemperaturevariesbetween25Cand30C

Theconstant

volume

of

the

quenching

medium

is

14

liters

Thesoundsignalprocessing programcalledSpectraLABwasrunningontheIBMnotebook

RESULTSTHESPECIMENBEFOREANDAFTERQUENCHING

RESULTSTIMESERIESDIAGRAMOFSOUNDPRESSURESIGNAL

RESULTSSPECTROGRAMOFSOUNDPRESSURESIGNAL

7/28/2019 Cracking Perception by Emitted Sound During Quenching

3/3

9/27/2011

3

RESULTSAVERAGESPECTRUMOFSAMPLES

RESULTS3DSURFACEVIEW

CONCLUSIONS Thearticlepresenteddescribesthesignalscapturedby

measuringacousticemissioncausedduringquenching

Thesoundpressuresignalwascapturedusingahydrophone

Achangeinsignalshapeappearscorrespondingtothe

formationof

avapors

around

the

specimen

Significantchangeofthesignalfollowedwhenthespecimencracks.

Significantchangeofthesignalisverymuchaudible(visible)andrecognizable.

CONCLUSIONS Itcouldbeconcludedfromtheexperimentalresults

thatthecapturingoftheacousticemissionwasreliableandhasgivensufficientresults.