effects of thermal cycling on carbon steel

7/23/2019 Effects of thermal cycling on carbon steel

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THE INFLUENCE OF THERMAL CYCLING ON THE CORROSION AND

HARDNESS OF LOW CARBON STEEL

Mr. Ashraf M. Elaieb1, Dr. Farag M. Shuaeib1, Dr Ramadan O. Saied2

and Mr. Mohamed G. Almalki1

1

Mechanical Engineering Dear!men!, Facul!" of Engineering, #engha$i %ni&ersi!", #engha$i, 'ib"a2Mechanical ( )ndus!rial Engineering Dear!men!, Facul!" of Engineering, *rioli %ni&ersi!", *rioli, 'ib"a

E+mail drfmshuaeib-"ahoo.com.*el 21/+0222/3

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ABSTRACT

*his :ork s!udies !he influence of !hermal c"cling on !he corrosion and hardness

beha&ior for lo: carbon s!eel ma!erial a! !emera!ures of 3 ;, , and o< andnumber of c"cles of 1, 2, 3 and ;. *his !"e of s!eel is chea and e=!ensi&el" used inindus!r" for s!ruc!ures such as hea! e=changers, condensers ies, boiler !ubes, cooling!o:er ies and similar hea! !ransfer e>uimen!s. During !he normal oera!ion of !hesee>uimen!s, !his ma!erial is sub?ec!ed !o !hermal c"cles :hich are usuall" belo: !he firs!

hase !ransforma!ion !emera!ure for s!eel @B23o


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increasing !he !hermal c"cling !emera!ure generall" increased !he hardness un!il abou! o


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Tabe !" ASTM#A$%&' Grade!(!) C*e+,-a -o+os,/,o0

Elemen! < Mn h S .1; + .21 .2 +.; .; .

Secimen dimensions h"sical shaeF,1. !" /es/ se-,+e0

DESIGN OF THE E23ERIMENTS

)n !his :ork a design of e=erimen! :hich uses !he Resonse Surface Me!hodolog"@RSMC couled :i!h a fac!orial design !o lan !he e=erimen!al :ork :as imlemen!ed.*he main fac!orial design :ould co&er a :ider range of !he rocess arame!ers and :ould

ro&ide a simle me!hod of resul!s resen!a!ion, :hile !he resonse surface :ould co&er anarro:er range L!ha! is belie&ed !o be more cri!ical and :ould allo: for a comrehensi&eanal"sis, and de&eloing an emirical model. Af!er !he design fac!ors and !heir le&els :ere

se!, based on li!era!ure &alues and also af!er erforming fe: !rials, !he design ofe=erimen! ma!ri=es :ere crea!ed, using M)N)*A# sof!:are. Subse>uen!l", !he !hermalc"cling rocesses :ere carried ou! according !o !he designed e=erimen! ma!ri=es lis!ed in*ables 2 and 3. *hereaf!er hardness, and corrosion erformance !es!s :ere erformed andresul!s :ere !hen in!roduced in!o !he designed ma!ri=es.

Des-r,/,o0 o4 /*e T*er+a Cy-,01 3ro-ess

*his rocess in&ol&ed !he follo:ing s!es and sho:n schema!icall" in Fig. 2. *:osecimens for each se!!ing @E=. NoC :ere hea!ed !o !he re>uired !emera!ure according !o*ables 2 and 3. *hen !he" :ere allo:ed !o homogeni$e a! !ha! !emera!ure for 1 hour.

Af!er homogeni$ing !he secimens :ere !aken ou! of !he furnace and immedia!el" cooledin :a!er ba!h @be!:een 2 !o 3 ouiredc"cles. Af!er all e=erimen!s :ere comle!ed, secimens :ere !hen !aken ou! for hardness,and corrosion !es!ing. *he hardness &alues :ere de!ermined on Rock:ell # hardness !es!er@R#+ kgmm2C. *he corrosion !es! :as based on sub?ec!ing !he secimens !o !heen&ironmen!al @)ndus!rial a!moshereC corrosion for a eriod of 3 mon!hs.

3


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F,1. 5" T*e /*er+a -y-,01 ro-ess

Tabe 5" T*e 4a-/or,a des,10 +a/r,6

E=. NoNumber of

c"cles


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RESULTS AND ANALYSIS

Af!er all !hermal c"cling rocesses :ere carried ou!, hardness and corrosionerformance !es!s :ere erformed and resul!s :ere in!roduced in!o !he re&iousl"designed ma!ri=es @*ables 2 and 3C, !he design ma!ri=es :ere !hen anal"$ed usingM)N*A# sof!:are. *:o !"es of anal"sis are resen!ed, !he firs! one is !he fac!orial designanal"sis @*able 2C, and !he second is !he resonse surface me!hod @RSMC anal"sis @*able3C.

Fa-/or,a Res8/s A0ays,s

Hardness results:*he form of !he ou!u! genera!ed for !he fac!orial design anal"sis issho:n in Fig. 3+a&b. As sho:n, !he fac!orial anal"sis sho:s !ha! !he ma=imum hardnessis ob!ained a! around !he o< and !he hardness in general increased b" increasing !henumber of c"cles. *he in!erac!ion be!:een !he hardness resul!s is no! clear from !he lo! in

Fig. 3+b, bu! i! does no! confirm !ha! !here is no in!erac!ion as !here are some s!ages :here!he lines are no! arallel. )! is !o be no!ed !ha! !he fac!orial design uses a s!raigh! lines !o

?oin !he resul!s be!:een le&els. *herefore, !he RSM anal"sis :as added !o !ake o&er !hislimi!a!ion.Corrosion results *he form of !he ou!u! genera!ed for !he fac!orial design anal"sis issho:n in Fig. ;+ a&b. *he fac!orial anal"sis sho:s !ha! !he minimum corrosion ra!e isob!ained around !he o< and !he corrosion ra!e in general decreased b" increasing !henumber of c"cles, !o a minimum !hen i! increases again. Once again, !he in!erac!ion

be!:een !he corrosion resul!s is no! clear. #u! i! does sho: !ha! !here is some sor! ofin!erac!ion a! bo!h !he beginning and !he end of !he resul!s. )n summar", i! can beconcluded !ha! !here is an agreemen! of eak &alue e=is!ence a! o< for bo!h !hehardness and !he corrosion measuremen!s. *his is &er" in!eres!ing finding. Also i! aears!ha!, increasing !he number of c"cles !ends !o increase !he hardness and decrease !hecorrosion :hich is more &alid u !o !he o< c"cling !emera!ure.

Reso0se S8r4a-e Me/*od 9RSM: A0ays,s

Af!er !he RSM ma!ri= is comle!ed b" in!roducing !he resul!s as sho:n in *able 3,!he design ma!ri= :as anal"$ed using RSM rou!ines in M)N)*A# sof!:are. *he full>uadra!ic model :as selec!ed !o anal"sis !he resonse surfaces. *he ou!u! resul!s :eregenera!ed in !he form of con!our lo!s and !hree dimensional resonse surface lo!ss!a!is!ical models :ere also roduced.

@aC


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@bC F,1. 7" T*e +a,0 9a: a0d /*e ,0/era-/,o0 9b: e44e-/ 4or /*e *ard0ess

by 4a-/or,a des,10 a0ays,s.

@aC

@bCF,1. ;" T*e +a,0 9a: a0d /*e ,0/era-/,o0 9b: e44e-/ 4or /*e -orros,o0 ra/e 9CR:

by 4a-/or,a des,10 a0ays,s

Hardness RSMAnalysis:*he hardness resul!s :ere anal"$ed and !he in!erac!ions of

!hermal c"cling arame!ers :ere iden!ified. Regarding !he s!a!is!ical model @see aendi=+AC, !he s!a!is!ical anal"sis for !he full >uadra!ic model for hardness resul!s gi&escoefficien!s of de!ermina!ion of R2 and R2+Ad? e>ual !o /.B and resec!i&el",:hich sho:s !ha! !he erformed hardness regression is good.*herefore, !he &erified model of hardness is as follo:s

HRB< # )7.== > (.$;77 C> (.&$$% T> (.((!7; C2

#(.(((&7T2# (.((!!( CT @1C

Jhere,HRBis !he hardness, Cis number of c"cles, Tis c"cling !emera!ure @o


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Hardness parametric study:*he effec!s of !hermal c"cling rocessing arame!ers onhardness are resen!ed in Figs. and as 3D surface lo! and con!our lo! ob!ained usingM)N)*A# regression model of E>.@1C. As sho:n , !he effec! of !he c"cling !emera!ure ismore significan! !han !he number of c"cles. Regarding !he number of c"cles, !he increaseis almos! linear :i!hin !he selec!ed range. o:e&er, !he effec! of !he c"cling !emera!ure is

increasing !he hardness in a non+linear cur&e un!il a eak a! o


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regression is reasonabl" good. *herefore, !he &erified model for corrosion ra!e is asfollo:s

CR (g)< ).(! # (.()%==C#(.(5%(& T> (.(((%$ C2

> (.((((7T2> (.((((= CT @2C

Jhere, CRis !he corrosion ra!e e=ressed as !he :eigh! loss in grams, Cis number ofc"cles, Tis c"cling !emera!ure @o


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F,1. )" T*e -o0/o8r o/ o4 /*e -orros,o0 ra/e as a reso0se a0d -y-,01 /e+era/8re a0d No.

o4 -y-es

CONCLUSIONS

From !his e=erimen!al s!ud", !he !hermal c"cling !emera!ure :as found !o ha&e moresignifican! effec!s !han !he number of c"cles on bo!h !he hardness and !he corrosion ra!e.)ncreasing !he !hermal c"cling !emera!ure :as found !o increase !he hardness anddecrease !he corrosion ra!e un!il o< :here eak is ob!ained, and !hen i! is follo:ed b" adecrease in !he hardness and decrease in corrosion ra!e as c"cling !emera!ure reaches o< . Emirical models for !he hardness, and !he corrosion ra!e as func!ion of !he c"cling!emera!ure, and !he number of c"cles :ere de&eloed using !he RSM aroach. *hemodels :ere found !o be reasonabl" describing !hese effec!s.

REFERENCES

H1I.www.sail.com accessed at May 2!.

H2I.www."ron and Steel "ndustry .com# The Canadian $ncyclo%edia.htm. Accessed at an2!.

H3I. #ello P.A., assan S.#. and Abdul:ahab M., Effec!s of *emering on !heMicros!ruc!ure and Mechanical roer!ies of 'o:


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H11I. Sidne" . A&ner, )n!roduc!ion !o h"sical me!allurg", 2nd edi!ion.ch/, 2/2+2/;.

H12I. . #. *rindade), R. #orin, #.Q. an?ari), S. ang, %. Pru, .K.

effects of thermal cycling on carbon steel

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