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Fracture Toughness Of A516 Gr70




KSME International Journal, Effect No. J, pp. lJ-J8. Temperature 2000 11 Frac Fr actu ture re Chang-Sun Chang-Sun Se Seok ok (Sungkyunkwan University) Frac Fractu ture re ough ough ss er orme orme 600'C, C, an temper temperatur atur ranging ranging from from -160'C to 600' n lo lo ad ad in in g m pl pl i an carb carbon on plat plat naly nalyze ze acco accord rdin in J -i -i nt nt eg eg ra ra l ITCT rela relati tion on o n l ud ud e ur ductil ductile-b e-brit rittle tle trans transit ition ion temp temper erat atur ure, e, an -IS'C re decr decr ased ased incr increa easi sing ng temp temper erat atur ure. e. mate materi rial al arou around nd -30·C. decre decreasi asing ng temper temperatu ature re wa signi signifi fica cant. nt. Key Words: duct ductil il brit brittl tl tran transi siti tion on temp temper erat atur ur of the - 3 0 ' C , th tende tendency ncy decrea ease se it Ie to decr J-Inte J-Integra gral, l, Fractu Fracture re Toug Toughn hnes ess, s, Tempe Tempera ratur tur ffec ffect, t, DBT ment J-int J-integ egra ral( l(Ri Rice ce plas plasti ti Intr Introd oduc ucti tion on deve develo lo Elas Elasti ticc-pl plas asti ti frac fractu tu tempe tempera ratu ture re data fractur tur toug toughne hness ss paramete paramete whic whic defi define ne IC frac toug toughn hnes ess, s, ther therma ma an of pe ur temp temper erat atur ure. e. Jun temp temper erat atur ur te these 19 Ther Theref efor ore, e, dete determ rm ne eval evalua uati tion on re values es at re valu transi transitio tio shelf an tran transi siti tion onal al toug toughn hnes es sson sson Th objec objectiv tiv pape pape effect of temp temper erat atur ur (Joy (Joyce ce elas elasti ticc-pl plas asti ti le de igni igning ng such frac fractu ture re perf perfor orme me temp temper erat atur ur systems. transinon mate ia construction. Th mate ns io pari pariso so in mu temperature hose hose 2. Fracture Toughness Test that that e no no u temp temp atur atur un tion tion of he degr degree ee tole tole te he DBTT dete determ rm ne es gnin gnin of mechanical pe a rb rb o th normal normaliz ized ed conditi condition on ha be uc pl used used ex ensi ensive ve io cons constr truc ucti tion ons. s. (Fra (Franco ncois, is, 1986 1986 With With th adva advanc nceeCorres Correspon pondin din Autho Author, r, E-mail: [email protected] TEL: +82-331-290-7477; FAX: +82-331-290-7482 u n k yu yu n a n nive nivers rsit ity, y, 30 Chunch Chunchunun-don dong, g, Jang Jangan an-g -gu, u, uwon uwon Kyon Kyongg ggii-do do (Man (Manus uscr crip ip Febr Februa uary ry 27 999; 999; evis evis ctob ctober er 999) 999) s ho ho w Table Tabl Tabl y. orie orient ntat atio io st nd of 'W 0.2S 12 Chang-Sung Table Chemical compositio of A516 Or70 (wt %) 0.24 1.07 0.013 0.00 0.06 0.035 0.20 0.38 0.21 Ta le ec anical rp rtie A516 Or70 Temperature Tensil Strength Yiel Strength rc: 628 -3 Orientatio of specimen Elongation(%) 451 2.2 Test procedure Fracture 18 ed c ed u ture rangin from -160·C to 00·C 10 598 20 569 200 ductile-to-brittle transition 549 373 29 363 31 27 400 34 600 hich covers 441 uppe of 160·C lOO·C is ac me ~ T ~ 6 0 0 · C . C at al o uall temperat re environm ntal chambe temp ra ur pa er lc performe exte omet spli contro encl in electrically te spli 63 tempera Temperatur mount _._f- the unit:mm Sp CO U'l mately a j W = 0 . 20·C and lOO·C. Figure the CO sche atic diagra temperat re _._. HC te ting system bser th uctile brittl transitio temp r unit:mm h ig h temperature extensometer specimen Fig. Specimen we ·C with self-adaptive ig temperatur extensometer wa mounted th speci gage SO.8 S p c im e controlled to better than temperature controllers otched to an initia where 'a jW rati te performe -160·C temperatur in temperatur temperatur environmenta chamber. Figure ti diagra atur fractu toughnes te ti ystem. Afte atig precrackin at room temperature, Effect Temperatur on th Fracture Toughnes re uction of 13 Gr carrie dynami universa testin machin at test tempera loadin interr pted unloadings(Smith riest, 986) an autographi re or an load-line displacement ea te t, pecime ofload obtained were om letely 6 - 1 2 . Result hown crac directly from th fractured surface. Al procedures with -15'C, O' 0' an IOO'C are 13-16. T ab l le values of R-curves [J C,(t.a) C2 obtained -160'C HIGH dWPERATlm ENSG'1ETER -30'C, ri ad ng to ct th de SPECIMEN ig was Il. calc late 01 I) J Q = ~ ( 2 + 0 . 5 2 2 ~ ) load-lin with high temperatur extensometer em inin 500 i' <400 380 zoo -\ Te.p. 1110 ig system 10'C 114 k N / . CRACKEXTENSION ig J-,1 cu vefo A516Gr7 stee with hi temperature extens meter at 20' 500 408 380 1110 -\ emp. 100 100'C 103 kN/m CRACKEXTENSION ig testing system J-,1 curv or A5 Gr teel with ig temperatur extensometer at lOO'C 14 1:1 Chang-Sun eo 500 580 400 40Q 300 300 1:1 101 100 p. 100 91 .:, 108·C tNt. 100 •• 100 CRACKItXTINSION curv fo A5l6 temperature extensometer at 500· J - ~ a J - ~ a temperature extensometer at 200· r - - - - r " " T T " - - - - - - . , - - - - .... 400 300 34MI .: 3 0 0 · C 9. J,e: th 5OOr----r--n--------,----, 400 100 500·C J,e: 85 Nt CRACKItXTINSION 580 p. .:, Te p. tN ,e CRACKItXTINSION CRACKEXTENSION J - ~ a Fig. 12 temperature extensomete at 300· 80 600·C tNt. .... J - ~ a temperature extens mete at 600· 5OOr----r-rr------,------, 500 400 400 300 p. J,e: 100 400·C tNt. Te p. 180 -15·C J,c: 113 tN CRACKEX'1'I'.NSION CRACKEXTENSION temperature extens mete at 400· curv fo A5l6 J - ~ a Results the fracture toughness parameter -15·C IC versus t h t em p er at u r a r e s u mm ar iz e in Table 4. th -IOO·C t em pe ra tu re s r an gi n to - 3 0 · C , th specimen were broken after some ductile deformation. However, - 13 0 C , - 14 0 C , -150·C an from -160·C th tests, brittle fracture occurred withou ductile deforma- tion at maximum load. v al u v al ue s u si n (Rice, 1968) th then calculated following conversion equation. Effect Temperatur on th Fracture Toughnes 500 16 r7 15 150 119 4811 ~ l i l a 90 380 100 .. Te.p. 108 60 El WIlH COD GAGE (;)WIT 30 O' J,c: 118 k N / . HIGH TEMPERATUR EXTENSOMETER 100 300 ZOO 400 TEMPERATURE ("C) CRACK EXTENSION e.m) Fig. 14 The effect of temperatur on th uppe shel region of DBTT J-l!.a curv fo A516 Gr70 stee with CO Discussion 5OO,..---r-rr--------,-----, xp 4811 ta s ho w l oa d- li n displacement ca be measured su cessfull by th 308 temp ratu ome ul rc 100 Te.p. 101 temp ratu lO'C lOO'C, respectively bu loa 118 kN/m he displacement obtained That atur extensometer CO CRACK EXTENSION emm> Fig. 15 J-l!.a curv fo A5l6 Gr70 stee with CO gage at 20'C 500..---.....,....,.,...-------,------, gage. Th ve temperatur dete mine that temperatures Figure elasti toughness, 400 nsome uppe shel ductile-brittle transition temperatur BTT) de crease with increasing temperature. Th IC value 300 follows: ZOO Te.p. 100 J. 100' C f l c = - O . 0 6 T + 115 kN/. te pe CRACKEXTENSION J-l!.a curv fo gage at loo' A516 u r [ 'C ] elastic-plasti fracture toughness[kN/m]. Gr70 stee with CO uppe shel temperature. Th (2) temp summ ri ed (3) C, ( tu L ~ a ) ductile-brittle transition R-curve C,] 88 Tabl ha while C, slightly reaching essentiall constant IC in reas initiall Chang-Sun 16 effect of temperatur on Test Method Temperature R-Curve [j rc: -rrrrrr.: IC CdLla) C,] 11C 51 Toughnes suppor provided Engineering tructu al Sungkyunkwan References transition Francois D. le ignificant 986, "Relation betwee Vari us te dency transitio temperature behavior of frac ture toughnes as similar to th re ults of others. Watainab Fracture Toughnes Transitio Curve, Engineer in Fracture Mechanics, Vol. 3, No.2, to " Ch ar ac  terization of Transition Temperature Be avio of IC Fracture Toughnes Parameter," 160·C temperatur -IYC, correlated as ollows 4000 (T-15) 10 -465. (4) 417-430. K. L., 1988 "Effec of temperaturej't J, Fracture Behavior Vessel Steel, A S T M STP969 pp 392-401. ue[kNjmJ. Conclusion Th ollowi conclusion were obtained fr ASTM 150-165. 18 Chang-Sun ,"Fracture oughness Frac ur Ni-Fe-Cr Alloys," Engineerin Mechanics, No.2, pp. 223-228. Mahmood, L. Irradiated Partiall Denitrided 422-430. Mild Steel, ASTM L., 999, "Role nd ignificanc of Sour Hardenin in Radiation Embrittlemen of Journal Nuclear I ro n Materials 270, pp 115-128. Unloading Compliance thod fo Crac ng re ompact Tensio cracke Charp Sp mens," ASTM pp. 375- 393. "A Path Independent Integral Approximat Journal Applied Mechanics, 379-386. V. 1988, "Determination ok of Material Characteristic Values in Elastic-Plas J -I n g r Testing ra sist nc urve," Journal an Evaluation I-II. Leng Me sure en by Compliance Fracture Toughnes Testing, Experimental Mechanics, pp. 122-127. Yo obor "Fractur ough Engi ee in Frac ur T ra ns it io n gi n, Mechanics, 589-600. S t n da r le Fracture oughness," A nn ua l ASTM Standards, Strain Fracture Toughness of Metallic Materials, Annual ASTM Standards, 399-90.