ss_4 - 23. Recrystallization is a thermally activated...

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Unformatted text preview: 23. Recrystallization is a thermally activated process which can be characterized by an Arrhenius-type relation. Suppose an aluminum alloy is cold work to a 75% reduction in cross- Sectional area. The alloy fully recrystallizes in 100 hours at T=256°C and in 10 hours at T=283 C'C. (a) Calculate the activation energy for this recrystallization process. (b) Calculate the temperature at which the alloy could be fully recrystallized in 1 hour. (0) Sketch a plot describing changes in hardness during the 1-hour recrystallization anneal. (d) How does the dislocation density change within the alloy during the 1-hour recrystallization anneal? P It: \00 \‘7 1 ('qu _ _ a}; . . ® T '3 to 455T ... “C2 \0 T2: ésé \ \ w ~ w 730% = w “s'm't *2:th w; 7 Dr \J — I k I "" Jr .I‘ ‘C J x (“a (V i" it) \\‘ \Jcp " _...:_—-—-w_ \ C. x ' ii“ka “ 1 o ' 7n ~— I ? ZNMBM \aL \OU " a: \ L W“ “t:- -.\--'~ _ -- "‘ JIM L 2.2 W0 B * MN VET“; © “i unhuw " I '_ , .\.\‘. tixk';tf\fc3=wkk\ \ l . .. _ u in; v k K L mil—"r" ,. . \i ‘3‘: in.” I. H I 8 NR $1.:\L..‘u‘=-f'1"\t“”‘ \ ./ ” ,__..- _ \ a r; - a- :A av- M‘xr PM / i‘hmmn' 1“ "- r; ‘JW \3‘ ._ . ..__._fi__.- '5. - myt-ogwtu'ahi‘we- “*3 ' i i “J: \- L - a 4 f“ gut-- t '- fimwmmxot’: "‘N‘t “Q‘s-3‘ C H .( w TN but"; To \E\‘:.\o£7¥{‘\‘\a~.>& \ a I Mvt‘f" (M l” R! “Vii-3' .1 ' £§E§Yi \ C LC Vt. blown—[r 12am-— ‘ka‘e “M- Ravfibwfi. 7‘0 W \AL'CQ &OQ\\.1¥5R*\\JIW 39W §mfi<5®p~hs N Souku‘; MAQA‘W w: No; - \omx‘m to \‘s New? MG“; : \5<3%V.. \8‘0 L " WAY. \% L‘uXem“ 0-???“ , Tws \s WWVVQ/W (:0be M KTth habxum/ LUWK V537. may; UHTE\\_ be;ka M Cow‘s .Wsw:u Riman, \gmwcs m sumac \mam 6&0 WC W‘IbNLuQAM 85- b'x—Co vas\ 0x33: 09 5*! Em amv 0w w \c—S-Lmvh mewc NT Wicks/5mg: bfiooub we“? 33% (k Mm W k M): avw‘kké \ O Twfi oc— \ 99; D \S‘o‘c. \x: “gym; ou..W‘u& N WEN; \WSEA§\ WVSMUl—Nrom * M kc=$oakm was M M35qu Eta?ng MW \Bwowz Hash/Y7 as p. (109%. 28. The yield strengths and fracture toughness values characteristic of several engineering alloys are given in the table below. Consider a structural application where a material must support a tensile stress of 730 MPa. If non-destructive testing equipment is available which can detect internal cracks and surface defects larger than 2 mm, which of the three materials would you recommend for the application? Justify your answer. \L { :- 15“; Alloy KIC (MPa—rn'm) 0), (MPa) Q T178-T651Al 23.1 5m : wtv. Ti-6Al-4V 55 1035 was 4340 steel 60.4 1515 bum-N 0% prW “Ari-21g 41:81 N 99 _...- SLEE‘NCEL Henrietta W assess wake To 51% WE {’Dpr "1%; WW. We . \L = rm: =5 to: E” “‘“§ SW53“\ \L =- €1,q “Va?” 29. A steel cylinder containing C02 gas at a pressure of 1500 psi is being transported along a major US. highway. A rock thrown up by a passing vehicle strikes the tank and creates a 1 cm diameter hole. a) Describe the conditions which would cause the cylinder to explode in response to the bullet hole sending steel fragments in all directions at high velocity; is) Similarly, explain the circumstances under which the gas would simply vent from the cylinder hannlessly. ' Wt: ‘(JEY vases: T0 Wfi: 63¢..wms W a».me Ushldl WmUck “37', Wt. wax W171; EQAM mavta. ma \% L : \SDDXYEA : \\_-\ a ‘F-fi m 09' saw-I" wet E 0.00:? A L: k®0¥g$ Vii \ V k = O~L\\D M§fl FM W. m war WWRK was s WALWL \~...... . Womas k’%%% ‘W OMx \‘\¥o\l~x\ W W N91, \MWK §$u~lér$T REC/ROSE W1 MEL Mum Rota Ugsmhuz NOB Nost glow k)ka W - Wessex-ca \s WKWEJS. M VHS)ka 960* FMSM Gag W0; {3:ka CFgfLNwJLL/ M051 Visa “:3 Owe mm, we 9: \ch stem ems Max:063 $5: EQXDW M WVCKLWJ S‘s»! Class two» ?k§u no? as— W 90k}; csth W arm/gamma m\mfifiz sf— WWL. L—J ...
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This note was uploaded on 10/03/2009 for the course E E344 taught by Professor Libera during the Spring '09 term at Stevens.

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ss_4 - 23. Recrystallization is a thermally activated...

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