EFFECT OF PRECURSOR MICROSTRUCTURE ON MORPHOLOGY FEATURE AND MECHANICAL PROPERTY OF C Mn Si STEEL

Æ 49 Í Æ Vol.49 No. 3 Ñ Æ 558 566 ACTA METALLURGICA SINICA Dec. 3 pp.558 566 ÓÔÜ É C Mn Si Û ÐÇ µ» º ² ³¼¼ ± ( Ø Å ÆÊ, 83) Å À ºÎ Ç Æ ¾ Õ Ô Ð (IQ&P) Ù.C.9Mn.3Si ²Đ ± Ä. ĐÎ ÔÙÇ ¹Ù, ËÇ Æ Æ (M) ²Đ É Ë Æ µ ( ) «Æ; µ ËÇ Æ Æ Ë Æ (B F) Ü ²Đ Ë Æ ß «Æ. Ç Ë IQ&P Ç Ù, B F Ç Æ²Đ ÓÌ Ö 976 MPa, Þ¹ 6.7%, ÂÌ 6 GPa %; µ Ë M Ç Æ Ì Í»Ð, ÂÌ Á 3 GPa %. Â Ò ¹ ÇÆÝ µ», B F Ç Æ²Đ Ç µ ÇÆÝ ¹, Þ «ÆÐ µ, µ¾ ÇÆÝ ¹ Á Ð ÓÙ, Á ÞÙ ÇÊ ; µ M Ç Æ²Đ Ç ÆÝ ¹, Þ «ÆÇ µ Ð, µ¾ ÇÆÝ ¹ Á е Ú, Á ÞÙǺ Æ. ºÎ ± «Æ Æ Ü ¼, µ à ΠºÎÇ Æ»ÌÁ. Æ IQ&P Ç, ²Đ, «Æ, ¾ ÇÆÝ ¹ ÞËÎ TG4. Đ ÀÖÑ A Đ 4 96(3) 558 9 EFFECT OF PRECURSOR MICROSTRUCTURE ON MORPHOLOGY FEATURE AND MECHANICAL PROPERTY OF C Mn Si STEEL REN Yongqiang, XIE Zhenjia, ZHANG Hongwei, YUAN Shengfu, SONG Tingting, SHANG Chengjia School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 83 Correspondent: SHANG Chengjia, professor, Tel: ()63348, E-mail: cjshang@ustb.edu.cn Supported by National Basic Research Program of China (No.CB638) Manuscript received 3 5 3, in revised form 3 9 4 ABSTRACT The effects of different precursor microstructure on the morphology and mechanical properties of the.c.9mn.3si multiphase steel which was obtained by the treatment of intercritical reheating quenching and partitioning (IQ&P) heat treatment were examined. Under the same IQ&P heat treatment parameters, multiphase microstructure which contains lath like ferrite matrix and film or short needle like retained austenite can be obtained by the martensite (M) precursor steel; while multiphase steel which has a bainite ferrite (B F) precursor can obtain a microstructure of equiaxed like ferrite matrix and particale like retained austenite. After the IQ&P process, tensile strength of the multiphase steel which has a B F precursor is up to 976 MPa, but elongation of this kind of steel is only 6.7%, and thus the product of strength and elongation of this kind of steel is only 6 GPa %; while multiphase steel which has a M precursor has realized the combined properties of high strength and excellent ductility, product of strength and elongation of this kind of steel reaches 3 GPa %. As for the work hardening behavior of the uniform elongation stage, although B F precursor multiphase steel has a higher work hardening index n than the M precursor multiphase steel, stability of the retained austenite in this kind of steel is relatively poor, variation behavior curve of the instantaneous n value with true strain for this kind of steel shows a notched like shape; as for the * µ À Ð Ü ¾ CB638 ± ÙÀ : 3 5 3, ± ÙÀ : 3 9 4 : ÊÌ, º, 983, DOI:.374/SP.J.37.3.3

Æ ÖÉË : ÆÅ C Mn Si À«Ð à 559 multiphase steel which has a M precursor, retained austenite in this kind of steel is relatively stable, variation behavior curve of the instantaneous n value with true strain for this kind of steel is much more steady, which shows a trend of gradual increasing. The reason for the different tensile testing and work hardening results above is related to the morphology, proportion and distribution state of the retained austenite and matrix microstructures, which is due to the effect of different morphology and microstructure characteristics of the precursor phases by the roots. KEY WORDS IQ&P process, multi phase steel, retained austenite, instantaneous work hardening index ½ ¹ ÛÌ Ý Æ Å Æ, ÌÑÚ Đ ½. Ì Ç Ç¼ (DP) [,] Ì Ç Ç ¼ Æ Ð (transformation induced plasticity, TRIP) [3 5] Æ Ç Ç ¼ Æ Ö Õ Ñ ± (IQ&P) [6 ] Í ± Æ Ç Ý C Mn Si ÝÆ Í. Ó, ¹ Ô ÅÃÌ, ± à ¼Í Ì Ö È ½Æ ÁÝ. Õ, Santofimia [] Í IQ&P È ±È Ç Ç Ì Ç (M F).C 3.5Mn.5Si Û (Ö 4.5 mm) Ú, Ï Ì Ç Ç Æ Ç Æ ³. ³ Ý Í Î ¼Ñ, Ø ÔÍ º ½¾ È ²Ü Î. ß ± Þ Mn 3.5%( º),  ÅÑ ± Mn È ¼, ½Â ÚÛÕ Ò»., Mn б È ÚÆ Å. È ÌÎÞ IQ&P Õ ÚÈ, ± Ö 6 mm Å.C.9Mn.3Si Ú, Í ±È»ÏÈ Ç ( Ç Ç Ì Ç), Ç Ç ±Í ÈÇÞ Å. Õ ÌÊ Â Ú Ø Æ 5 kg, Þ²Æ ( º, %) : C., Mn.9, Si.3, S.75, P.6, Fe. Õ, ÚÆÖ 6 mm ƾ, ØÛÌ RJX 8 ± Õ ÕĐ ÓÞ h,, 7 À È Æ 6 mm Ö. ² 86, Ø Ø. Đ² ½ Ô 6 mm mm 8 mm. ÌÕ º Ø Õ Ú A C3 =856, A C =738, M s =346 (A C3 Õ ÛËÕÌ ÇÐ Ç ², A C Õ ¹ ÇÅ Ç, M s ØÑ Ç Ä ), À, Õ Ú È Ý. ²Û, ² Ø 4 JU ± ÕĐ 9 3 min Ð ÇÞ, Ø½Ñ (W.Q) Ø (A.C) Đ»Ï È Ç ; ² Ö ÕĐ 78 (Æ ) 5 min, Ø Ú Ç± Mn, C ŠDZ «, Ø½Ñ 3, ½ Æ Ô, ÛØ 78 3 Ø 8 /s Ñ, ̱³, 6 s Ø, Ì Ø Ê, Ö Þ ± 4 ( È ) 5 min, Ø Ø. Ì È Õ ÚØ Æ²É 5 mm Ô. Ô GB/T 8, Â.5 3 s. Ô Î Î, 3% Û (Ç Å º) Ü. Í DMAX RB X ¾ (XRD) ±³ ± Ç Æ C Õ, È µ 4 kv, 5 ma, Ð.. ÛÌ Oxford EBSD Æ ULTRA 55 ¹ (SEM) ± Ç Æà ½Â ³, Ð ¾ (EBSD) Æ. µm. Í Å, ß, ÌÓ º [3] Û Ç () γ, () γ, (3) γ ÆÌ Ç T, o C 9 o C, 8 s W.Q./A.C. 78 o C, 9 s W.Q. 4 o C, 9 s 3 o C A.C. ß.C.9Mn.3Si ÔÙÇ Ë Fig. Schematics of heat treatments applied to the.c.9mn.3si steel (W.Q. and A.C. represent quenching in water and air cooling, respectively; T temperature, t time) t, s

5 ( # 56 6;,I, %IA# ~r =_!O O 5.. W XRD.N, 5(< b!o I 6 %J AG E.a,a,a. = _!O C f 8 T v ; < : ()α, ()α U ; <, C& ()γ ()γ [4] (3)γ ω(c)γ = (aγ.35467)/.467 () %, ω(c)γ = _!O% C # 5.; aγ I6 h = _!O C E A G E., nm. J ( ^, W Si, Mn % =_!OA G E. M! C 5 Æ ', Wt %u/_ M [5].. q e\ [ BE 9!Oz 3 min tm A z 3 min t fta e d vb 5 ( y[ a j b A. W [d#, E H / W PCe d v t5 ( R7!OPeO jw!o A Æ=,7T7OA U N B PeO. W B% Mn f,=.%, D" tmet%- _O N, G*Ueft dtb % v!o. &P Y / WPeO B E t! IQ&P d v t,.c.9mn.3si Æ 9!O {.C.9Mn.3Si AD\d u s a[a Fig. Microstructures of the.c.9mn.3si steel after different preliminary treatment (M martensite, B bainite, F ferrite) (a) quenched after 9 for austenizing (b) air cooled after 9 for austenizing Æ 49 U A B 5(y[ 3a j b A. Ee IQ&P dv t, sbc&zpy ^T7O!O [6 8] AÆg~!O/= _!O [6,7] AB N ' B. W [d #, Gm 7 f 7 ; T / W, ;m 7 f 7B j m 7 f 7B P y ^ x & %!. ;m 7 f 7 e } Æ, ^ \ v ' P 9 Z7, 5 ; * m 7 f 7 y ' e }n, ^ \ v ' v {, 4 5CF. *jt7o (IF)[] ÆT7O (F) Pn ; *=_!O/g~!O (RA/UM)[6,7] v!p}æ ;!O (B)[6 8] y<< ;G = _! O g ~!O, t P/ ay 7. W!O` ` b!oæ R 4 Æ [p= _!O P <<S n 7E, W*t SEM v p /[r &K_l ' ^ q. W [ 3a d#, PeOe!O ' B % fy *! OB, K%!O [p % * Æ, T7O O y v ' P R7 _h!oa3 d ^, =' B%!*-: =_!O/ g~!o ; C v'ptæ *7 7. U e\? [ 3b, PeOe!O T 7O ' B B % yfy * '!OB, T7O O y v ' P =,7, t [p Z 5 &x v P#!OPeO ' B % s5b ; g ^, =' B B % = _!O/g ~!O ; C % ; 4 5 { 3 N i N S6N 'OdN A D _ q p l $i9 4OB u s SEM Fig.3 SEM images of.c.9mn.3si steel with martensite (a) and bainite ferrite (b) as precursors treated by intercritical reheating quenching and partitioning (IQ&P) treatments (RA retained austenite, UM untempered martensite, IF intercritical ferrite)

Æ ÖÉË : ÆÅ C Mn Si À«Ð à 56 ÔØ µm, Ø Ú³ Æ. IQ&P È Ú Ñ ² (3 ) Å Õ Ú M s, È ² ±Ñ Ù»Đ Í Q&P ± Ç. Ä Æ Kim [9] Á, Ø Ö Õ Ì±, Đ¹ C Ñ Å Ç± «, µï Ð M s ³Å. 4a b ²È Ç Ç Ç Ì Ç ÕĐ 78 Ö 5 min ØÑ Õ., Æ Ö Õ Ø M s ²ÜÅ IQ&P Ì Ñ ² (3 ), ÏÈ Ç Ç Ì Ç ³ M s ±ÅÅ, Ï ØÑ Ñ ² (3 )»Đ¹ Ç, Ø 4 Ú Ý Ø Ç ½ C Å C DZ «Ì, ½Ã Ø ³ ±»Đ Ç.. Ò ³  IQ&P È ÚØ ³ Đ² ½. ², ØØ ±²È Ç Ç ³ ³, È Ç Ç Ì Ç ³ ³. ϳ, Æ Ö Õ Ñ Ú Ø, ³ ÔÍ Â 9 MPa, Í Ú 6 MPa, Óº  %, Ø Ú 6%. ³ È ÔÍ, ß Í Å, È Å Í, à Í.65, Å ³ Í.7;, Ï ³ Ø Å, 6.7%, à ÔÍ, ßÍ Å ( ÔÍ Ø É Å) ÑÅ 7 GPa %. ³ ÔÍ Å, ß Ø Ñ 34.%, Î º ½ Ã Í Å 3 GPa %., Ø È Ì Õ Ú È ºÚ, Ì ÇÈ Ç Å Û Ú º ½ÆÍ Å. Ä ÈÁ Á [] ±, ±Æ.3C.8Mn.35Si, È Ç Ç ³ Ì 3 Ú, Óº Ø 6.4% 8.6%, Í Å 6. GPa %, Å ³ ²., Ø Ï Ñ ² Ú (3 ) Ì (4 ) Û Å º ½, Û Å Í Å. 5  ³ ÈÌÂĐ ÈÌ ÂĐ Â. Ï, ØÆÀÔ Ì±, ÈÌÂĐ Â ÈÝ Ò Â, Ø ÝÈ Û É. ØÆÀ Ó º, ÂĐ Â ßÚ, ñ ³ ÂĐ Đ 77 MPa, ³ ÂĐ Ý Đ 4 MPa. Ï 5b, Ø Â Å 3.7% º, ³  Amount of expansion, m - - -3 (a) M s =67 o C Amount of expansion, m - - (b) M s =6 o C -4 5 5 3 35 4 45 5 Temperature, o C -3 5 5 3 35 4 Temperature, o C ß 4 ºÎÇ Æ.C.9Mn.3Si 78 Õ 5 min Ð Ð Fig.4 Dilatometry curves of the specimens obtained by reheating to 78 for 5 min, direct quenching to the room temperature for.c.9mn.3si steel with M (a) and B F (b) as precursors Á ³ ¾ Table Mechanical properties of (with M as precusor) and (with B F as precusor) multiphase steels Material R m, MPa R p., MPa YR A gt, % A, % R m A, MPa % 98 65.7 5.3 34. 3395.6 976 636.65.6 6.7 659. Note: R m tensile strength, R p. yield strength, YR yield ratio, A gt uniform elongation, A total elongation, R m A the product of tensile strength to total elongation

56 Æ 49 Í Engineering stress, MPa (a) 8 6 4 Strain=.38..5..5..5.3.35.4 Engineering strain True stress, MPa 4 8 6 4 Strain=.37..5..5..5.3 True strain ß 5 ²Đ ÇËÁ ÇËÁ Á Á Ð Fig.5 Engineering stress strain (a) and true tensile stress strain (b) curves of and multiphase steels Đ Å ³, Ø Â 3.7% Ø º, È ÂĐÝ ²Ü Ø. Í Õ ³ ± ºÆ, ± 5a ± ÂĐ Â, Ø º, Ï ³ Í Å, Ø Æ Đ ÌÚ ½¹, ³ Ø º ÈÌÂĐ Æ ÂĐ Å ³. Ï ³ ÈÇÞ ±,   3.7% (ÈÌ 3.8%) Ø, ³ ͳ ÂРе»±Â ³, Ï Â» Ú, Î ÐÕвÜ, ±ÂĐ 5b ±, Ý³Ý Ø 3.7% Ø Ó º, È Â Đ Â ²Ü Ø..3 ÈÇÞ º (n i ) ÌÕ Õ «Ô ÈÇÞ ², º ÌÚ [] Õ : n i = d(lgσ i) d(lgε i ) = d(lnσ i) d(lnε i ) = ε i(dσ i ) σ i (dε i ) () ±, σ i ε i ܳ ÂĐ Â, dσ i /dε i Ý «ÈÇÞ. 6, ÆÈÁÈ [] Ô IQ&P (3, Ø ± I) ³ ÈÇÞ º Â, ÏÁ ÂĐ Â Ð, ñ E I, E II E III ±Â Ó Â ¹ È 3 ³ n i Å Æ ±Â Â, ε u ¹ È Ó Â Ú, ε u =n i «Ñ Æ []. Ï, 3 ³ ÈÇÞ Ú Ø 3 Àº : ()  ε < E i (i=i, II, III), n i ¾ Æ; n i.35.3.5..5..5 E II E III E I Strain=.37 I []...5..5..5 True strain ß 6, I [] ²Đ ¾ ÇÆÝ ¹ Á Ð Fig.6 Plots of instantaneous strain hardening index as a u =n i founction of true strain for, and I [] multiphase steels (ε u uniform strain, n i instantaneous work hardening index, E I, E II, E III strains at minimum n i value of, II, III multiphase steel) ()  E i ε ε u, ±Â Óº Á Ð, n i Ü½ß µø  ¼ ¼ Î Ø À º ; (3)  ε > ε u, «¹,  ßÚ, n i Æ.  Æ, ÕÇÞ Đ¼Ð. Ï 3 ³ ± ß Ì Ç 5%, Ü ¹, ± Ç Ç ÚÂĐØß ± µã à Õ, ßÏ Õß ÛÕ ÈÇ Þµ»½ «Ì Ç ÛÕ ßÞ., Ø º (ε < E i ), 3 n i ÌÚ³µ³ Å, Ç Ù Å Ç¹. Â ß Đ Ì (E i ε ε u ), Ñ Ç²¹ л Æ

Æ ÖÉË : ÆÅ C Mn Si À«Ð à 563 Ç. Ï Ç Đ¹ ÇÅ, Ï Ç¼ Đ Ú Õ, Ï Ð ÍÞĐ¹À Ç À¹ n i Ú³, µ n i ܽ. Ì Ú, ± Ç».   Ӻ ( ε > ε u ), Ú ³º Ñ Ç Ç, Ï ÍÞ ÛÕ ÈÇÞ ½Đ, ± Ç, n i Ú³, «Ý Ý«. ØÆÀ Ó º, È Ç Ì ÇÈ Ç ³ ÈÇÞ º Â Ø ÈË, È ÔÚ È Ç Ç ³ ÈÇÞ º Â Ý Û, Ï Â ßÚÈ». Ã È Ç Ç I [] ³ ¼, º (E III ε.) Æ Ý ÀÅ Ú, à ÈÇÞ º  ØÆ Ç ÈÝ ³», ß Ü½Å ³. ÄÆ Þ [3], ±È ½ ÈÇÞ º È TRIP  РÆ. ³ Ú ÈÇÞ º n imax ܽ ³, ³ n imax Ý ²Ü TYPE III ³ ;, ØÆÀ Ó º, n i ØÆÇ È Ý >>I., Ø IQ&P È Ú, Ì Ç Ì Ç È Ç ÇÈ ÇÅ Û ÈÇÞ ½, ØÏ IQ&P È Ê Ú Ì Û ÈÇÞ ½..4 ÅÆ Ý «ÄØÈ Ù Ì XRD ± ³ ± Ç, ¼Ý 7. ¼Ñ XRD, Đ ³ Ç (f γ ), º (a γ ), Ç C (c γ ) Æ Ç± Û C (f γ c γ ) ² º, ¼Ý³. ϳ, IQ&P Ú Ø, ³ ± Ç Ú,  %. Ã Ç C ¼, ³ ²Ü ³ ; ± ³ ± Ç Û C, È Å Ø. ÄÆ Mahieu [4] Á, ± Ç M s Ï Ã Å C, Mn, Si Ñ, Ú ³ : M s = 539 (43 c C ) (3.4 c Mn ) (7.5 c Si ) (3) ±, c C, c Mn, c Si ܳ DZ C, Mn, Si ( º, %). DZ C ϳ Intensity, a.u. () () () () (3) 5 6 7 8 9, deg ß 7 ²Đ XRD Fig.7 XRD spectra of and multiphase steels Á ³» Table Metallurgical parameters of and multiphase steels Material f γ, % a γ, nm c γ, % f γ c γ, % 3.368.4.8 6.363.7.9 Note: f γ volume fraction of retained austenite, a γ lattice parameter of retained austenite, c γ carbon concentration of retained austenite, f γ c γ the total carbon content of retained austenite ±, ÌÈ Ø 78 Õ, 5 min, Ï º Ú Ì± Mn Si Ý«, (3) ± Mn Si Ø Æ.9%.3 %. Ï (3) Đ, ³ ± Ç M s 9, ³ ± Ç M s 3. M s ²ÜÅ ( ), Ï ³ ± Ç ½Ø ÚÒØ»¹ Ç., Ï ³ M s ÅÅ, ³, ØÚ È ± ÇÈ Å Ñ. ½ ³ ÈÇÞ º Â, ³ ÈÇÞ º Â Ú À..5 EBSD Ï Â Å ± ³ ± Á ÝÆ ½Â ³, Å 78 µm 56 µm À µ Ì EBSD Á, ¼Ý 8. Ï ³ ± Ç 8.3% 5.5%(ÇÅ º).

. =_ 5 ( # 564 &, W ' EBSD ~$ 3G ", [%n. & ^[pt. µm Av =_!O, Gg, W[A = _!O 5 &x P# W XRD A > 4 A =_!O. Ue& EBSD AÆ XRD (.A =_!O ;!*, \ t PEAT IQ&P P C:.v, 8T!O T7O PeO dmz [pæ. µm =_!O. W[ 8 d#, j 4A% =_!O t ÆO P y ^!} 5 J. %= [%A B % { = _!O t G Æl [p 5 ; Y, y[ 9 A. W [d#, s B %X v ' i { Æ 49 U!Ot G ( e 79.%, e 76.3%) j l ( e 97.3%, e 95.3%) [pt µm Av. LNYZkz [5,6], e h TRIP J, = _!O [p Jt. µm, [p e v jeæ = _!O / B h : [7 9]. = A,, E IQ&P PC d v t s ' B = _!OX v '. [p t µm A,. ' 5 ` Æ [p= _!O n t, n A B ( t p e T % V- &x TRIP J. t 3 POz. ni #, ye ni te.! Tv' t, t;h*l J$b, Pyx{E^, )m & A 8 EBSD Fig.8 EBSD images of (a) and (b) multiphase steels 83 (a) (b) 844 8 8 Size distribution Size distribution 6 4 5 3 Length, 3 4 38 5 6 m 4 5 m 54 (c) 4 33 (d) Size distribution 8 6 8 6 4 4 9 3 Length, 6 Size distribution 4 6 46 35 Width, {9 6 m 3..5..5 Width,..5 3. m i & A$ <^ NsF ik {ZoX Fig.9 Distribution characteristics of retained austenite s grain diameter in length (a, b) and width (c, d) direction for steel (a, c) and steel (b, d)

Æ ÖÉË : ÆÅ C Mn Si À«Ð à 565 ÎØ º, ( 6). Ï 8 ß Đ, ³ ± ÇÌ ÇØ ³ È Ê, TYPE II ³ ± ÇÌ ÇØ Ý³È. ³ ± Ç³È ; ³ ± Çݳ, ºÈ., ØÌ Ç Ç ß ½ «ĐÅ BS (band slope, ÄÏÛ ). ÄÆ Kwon [3] Ryde [3] ± ³ Ø BS ± Á¼, Þ ¾ (fcc) Ç ( Ø EBSD ± Õ), Ç Þ¾ (bcc) Ç Ç Ú Õ È Å BS (<55),»ÈØ BS ³Ý È «½Đ ( 8 ±«ÐÒĐ); Ç Þ¾ (bcc) Ì Ç ÝÈ Å Õ, BS (=55),»ÈØ BS Ý³Ý È É ½Đ ( 8 ±ÉÐĐ). ² 8 ± BS 3a b ± SEM ±, «ĐÄ ½ Ç Ç. Ï, ³ ± Ì Ç Ç Æ Ç/ Ç Ç ÔØÆÇ ±Ú ³ ± Ç, ¼ 3 ± SEM. ÄÆ Kwon [3] Á, Ø BS, ¼Ñ BS ± ½ Ú ³ ³ ± Á ÝÆà ½. 8 ± BS ±Â ÄÏÛ ± ½. Ï ³ ± (BS=55) Ì Ç Ý 74% 66%, Å (BS<55) Ç ÇÆ Ç Đ ÝÝË 7% 34%. ¼ Ï XRD Ç, ³ ± ÇÆ Ç Ç Đ Ý 4% %. 3 Í ÚÐ Relative frequency, %, Ì»Ï È Ç Ý± 8 7 6 Low BS value High BS value 73.5 65.7 Intermediate BS value.4.3... 8 4 6 8 4 6 Band slope ß ²Đ BS (band slope) Ð Fig. Change in BS (band slope) curve for and multiphase steels ±³ Ô ÆÃ Ý Ñ. Ï ³ È Å³ Ç Ç Ç, ÏÇ Ô ±ÅÚ, ³ ÔÍ Å. ³ Ï Ç, Ï Ô ± Æ, ± ³ È Å ÔÍ. Ï ³ È Ç ( Ç Ì Ç) Ï Ð ÇÞØ Ø, Ì Ç Ô Ú, ÏÌ Ç¼ Õ Å; ³ È ÇÝ ÏÑ Ê Ç, ¼ Õ, Ø 78 Æ Ö Õ, Ç ± Õ Ú³, ß Ç ¼ ³ ÇÌ Ç ¼ Õ Ø ³ Ì Ç Ç. Ï Ç± Í È ÊÞ, ³ Í Å ³. È, È C Ç Å Ñ, Ô ½. µm Ç ± TRIP ÂÈ Ü½ ÊÞ., Ç Æà Š½ бÃÑ Å. Á³², Ç ÇÈ Å Ñ [3], ½ ÇÆ Ç Ç Æ Ç ÇÝ È Ñ [33,34]. ÇÒØ Ç Ç, Ø Ì±Ç ² ²Đ  Ç, ÃØ Å ÑÚ ¹ Å Ç. ¼Ñ 8 EBSD ¼, ³ ±È ³ Ç Ç Ç, ñ Ǽ, Ï Ç ½, Æ Ú Ô Ç Ç ( 8b);» TYPEI³, ±È Ç Ç Ç, ñ Ç Ç È, ¼ È ½ Ñ (Æ ) Ì Ç Ê, Ã Ç Ç Ô ±Æ ³ ( 8a)., ³ ± Ç ³ ± ÇØ Å Å Ñ, Ø ½ Æ È Å Ó.  ³ º Æ Í Å Î ³ À,  ³ ÈÇÞ º  ³ ³ À. 4 Ð () ÌÆ Ö Õ Ñ ± ÚÈ, ±È Ç Ç (M) Ç Ì Ç (B F).C.9Mn.3Si Ú, Đ È»Ï Ç Ç ³. ³ ÔÍ Â 9 MPa, Í Ú 6 MPa, Óº

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