EFFECTS OF B ON THE MICROSTRUCTURE AND HYDROGEN RESISTANCE PERFORMANCE OF Fe Ni BASE ALLOY

Ð 45 Ð 2 Vol.45 No.2 2009 Ï 2 Ï Ð 167 172 º ACTA METALLURGICA SINICA Feb. 2009 pp.167 172 B ³ Fe Ni ¾ ÊÅ ¼ Í (Ð ÍÖ ÄÍ Đ ², µ 110016) ¹ ÆÁÔ ³½» Í Ô Íº B Ð Fe Ni Æ Õ Ô Í. º Ä: B ÅÀ Þ ¼ ßÒ η(ni 3 Ti) Ý, ßÒ ÚÝ Ê Û, ÇĐ Ï Ô Í. Þ ³½, ÐÃÚ B, ÅØ ¼ À ¼, à η, ± Âß ± ßÞ Å ; ßÔ, H η/γ Ò ÉÅ, ʱ ±ßÞ, Đ¾ B ßÔ Đ ÂßÞ. ¹ Fe Ni Æ, B, η, ÔÜ Á û TG135 ÈË A È» 0412 1961(2009)02 0167 06 EFFECTS OF B ON THE MICRORUCTURE AND HYDROGEN RESIANCE PERFORMANCE OF Fe Ni BASE ALLOY ZHAO Mingjiu, RONG Lijian Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 Correspondent: RONG Lijian, professor, Tel: (024)23971979, E-mail: ljrong@imr.ac.cn Supported by National Natural Science Foundation of China and Chinese Academy of Engineering Physics (No.10476030) Manuscript received 2008 08 21, in revised form 2008 10 15 ABRACT Effects of B on the microstructure and hydrogen resistance performance in an Fe Ni base alloy were investigated by means of optical microscopy, scanning electron microscopy, thermal hydrogen charging experiments and tensile tests. The results show that abundant η(ni 3 Ti) phases precipitate at grain boundaries (GBs) in the alloy without boron (FN) after aging treatment, while only a few carbides precipitate at GBs in the alloy with boron (FNB). Tensile tests indicate that the FNB exhibites not only higher ductility but also lower hydrogen induced ductility loss than those for FN alloy. Fracture observations show that the brittle intergranular fracture is the main feature of peak aging and over aging FN alloy and quite a few secondary cracks can be observed on fracture surface of the hydrogen charged samples due to the precipitation of η phase at GBs. However, the intragranular fracture is dominant feature for the FNB alloy whether hydrogen charging or not. KEY WORDS Fe Ni base alloy, B, η phase, hydrogen induced ductility loss ÖÑ Fe Ni Ç Ø Ø Ç ², A286 JBK75, ½³ Đ Ô² Ø, Äß Ø È Í» [1,2]. Þ ², ÀÆÕÎÌ ², ³ Õ À ², Î ÎÐ Ù. ÖÑ Fe Ni Ç Ø Û ¼ Î, Ò Á Õ Î, ¾ [3,4]. * ¹ Ý Æ ËÂÆ ¹ Û Î½ Æ Å È 10476030 : 2008 08 21, : 2008 10 15 Ô : Ä, Ê, 1973,, ³ Ø ÑÛÌÄ ØĐ Ni 3 (Al, Ti) (Î γ ) Ñ, γ ½ ĐÞ, ÇÇ Á ². γ, ³ ØĐÁ ÄÞ ÇÇ Ë Ü Ø Ü, M 23 C 6 Ni 3 Ti (η ) [1,3 5]. Ñ½Ê Õ Å [6,7], H ÃÜ«γ ÇÇ Ó ÓÀ, Ü«Ç ÓĐ. É ÕÌ [8], Þ ÇÇ Ó ÓÀ Ñ H, H à ÅÁ«Ì, Ø ÕÂ. Fe Ni Ç ØĐ η, ² ÓÞ η ØÕݲ ß Ê [3,4]. B Ô ØĐ É, B Î Ø Ô¼ Î, ÑÛ [9 13]. ²Ä B

168 Õ Ð 45 Ô ØĐ Èß, É ½Ý Ò B «Ä Ó, Ó Ò, È ÓÐ ¼, Ó Î¼ [13,14]. ¹Á [15], «Ä Ó B Ã Ò Ù ØÑÛ. B ½ ØĐ É [16,17], ²Ä ³ Ø Đ, Á Å [16], ÔÛ ½ Đ, B à M 2 B Ü ³ ÓÞ Ñ Ó. ÖÑ Fe Ni Ç ØĐ Ú Á 0.001 0.01B ( ) [1 4], ²Ä É ØĐ, Ñ. Õ, ÖÑ Fe Ni Ç ØĐ «B, Á ß Ó η Þ, Ø ½Ô, Ø Õ Î. Õ ÖÑ Fe Ni Ç Ø, ½ ØĐ B, Í Á, B ³ ØĐ ; ½ Õ, ÍØ ÂÕ (SEM), B Ø Ö Õ Î ß. 1 µ Ø ¾, Đ½ Ø ( FNB Ø) 0.001B ( ), ½ Ø ( FN Ø) B. B, Ø Æ (, ) 30Ni 15Cr 1.3Mo 2.4Ti 0.3Al 0.25Si Fe(Å ) ½Ý. 1160 /12 h Á, Ä 1120 Ý ß 14 mm Æ. Á ßÛ : ± (), 980 /1 h, Í; «Ù (), +740 /8 h, ; ½ (), +800 /8 h,. Á 5 mm, Æ 25 mm. ½³ Ü Õ, : 300, 10 ÄÕ ( 99.9999) 240 h. Zwick Z050 È Ü, 1.3 10 3 s 1, лۻ л Ù. Ø Õ Î ÕÝ Â (ψ L ) Ü, ³ ψ L = (ψ ψ H )/ψ ( Đ, ψ ψ H Ñ Õ Õ ÀÃÙ). Ø È Ç, 40, 10 ¼ĐÜ ÕÑ ; Olympus GX51 Ø Ü Ø ¾; Ö ¾ ß Þ HatachiS 3400N SEM Ü. ³ ß ² «, Ç ÕÑ, SEM ¾ß Þ Ö. 2 º  2.1 B ÌÉ ÏƱ Î Á, ØÚ Ö, Á º, Î Þ Å, º TiC, TiN Ti(C, N), ±½ Đ [4,18], Ó Ti(C, N), 1 ŵ. FN FNB Ø Á Ö. 2 Á FN Ø Ö,, Á, ÓÞ η, 2a b η ØĐ. Á, Ø Đ η, 2c ŵ. η ½ Ç Fe Ni Ç ØĐ ¾, ³ Ø Ú Á Ti Al [19,20]. ½ ², η Á ØĐ ¾, Cicco [1] A286 Ø, ½ 730 /217 h Á ØĐ ¾ η ; Brook [4] ½ 720 /450 h Á A286 ØĐ ¾ η. Đ, Û ½ 740 /8 h Á, Ñ B FN ØĐ Þ η. Ç FN Ø, FNB Ø Á Ñ ¾ Á η ÓÞ, 3a ŵ; Ú Ó Á º Þ, Î Þ µ º M 23 C 6 Ë Ü. β 800 /8 h ½ Á, ¹ ÛÁË ÐÆ η ÓÁ ¾, 3b ŵ. ²Ä FN FNB Ø ½ Đ Þ, B ß η Ҳѹ. Å [1], Ø Ü Þ γ ½ Ø, Æ Ä Ô ½ ĐÃ«η «. η ½ ĐÃ Đ ½ Î ÓÁ γ Ò, «ºË [20], η γ, à γ Ú [21]. B Ti Ú Ä«Ó «É, B ØĐ Ó «Ö«Ñ. B Ó ««[22], Ƶ Ê Ì Ï ÅÑ [23,24], Ò «B Ã Ó 1 1.5 nm Û B Ú [24]. ½ Đ, «B à Ti Ê «Ó, È ß η, FNB Ø Á Á ¾ Ó η Ê. Ä Ô Û, Î ÓÁ Ti Ê ß, Ã˲ η Ä 1 È ³ Õ (FN, ) Fig.1 Microstructure of Fe Ni base alloy without B (FN) after (the Fe Ni base alloy with B (FNB) has the same structure as FN)

l2e dk g : B Fe Ni M:r d p7 o Td? L 169 ;s~e 2 FN η Fig.2 η phases in FN alloy after aging treatment (a) optical micrograph, as (b) SEM micrograph, as (c) SEM micrograph, as l p3*e/ U 1 Table 1 Tensile properties of the uncharged hydrogen samples Alloy Heat treatment σ σ0.2 δ ψ FN 619 1123 972 608 1076 967 235 725 584 230 711 582 52.4 25.8 26.9 51.0 29.4 29.8 81.6 43.5 40.0 83.5 60.6 59.0 FNB Note: σ ultmate strength, σ0.2 0.2 yield strength, δ total elougation, ψ area reduction { p3*e/ U8pxC I` 2 Table 2 Tensile properties and hydrogen induced ductility loss of the charged hydrogen samples L ;s~erew 3 FNB Fig.3 Carbides in FNB alloy after aging treatment (a) optical micrograph, as (b) SEM micrograph, as L IzE, a 3b M). C QA\ /Z<t I9 B `+f\ o_ r [14,24], g,\<t [ B V( 2a SFx \ oz Ef R=. GL FN <t EI[[ B, n Ih f Ti Al, = Ti R > 8" a ovp, i η f 6 6ZX #f n=, y& FN <tw~ I+VzE7Z5f η, a 2a M). 2.2 B(η T) (38HOIY1:DYB V 1 i FN 9 FNB <tf1p0 V, G b, w~ I +B, FN 9 FNB <t f m w O D ^, Vf5 B f [ ~ Q<t f m w 9D E IA. G <t f q y D Ja (b 2) b, Q3 < tfqyd Jav 4i, g,=i\ f Fe Ni O Alloy Heat treatment σ σ0.2 δ ψh ψl FN 622 1114 957 600 1071 966 251 729 602 242 727 608 52.0 21.2 20.8 52.0 24.8 27.2 81.0 22.3 24.3 81.8 36.0 38.8 0.7 48.7 39.3 2.0 40.6 34.2 FNB Note: ψh area reduction of hydrogen charged, ψl hydrogen induced ductility loss /Z I>4f q V. G 1 9 2 b, O Q<t # `, ~" I + (! 9 ) B, FNB <t I FN <t f 1p$ D 9 ifqyd Ja, hr=o3 <t " 1< ze f#`i&. 6, GL FN <t#3 B, h \ " 1 < z E 7 Z 5 f o η, $ 1 < <rk E \ η O OZ o f oh I F! " a, 9 <t1p$ D f f i ; FNB <t G L B f[, 7{7 η fze, 5 osfx (w I+B\ o zes f η ) [o, =M, h1p$ D h FN <ti. h N, GL η O OZ o f! oh (η/γ),mf H, H S8\ ohi T, K \ $ f 1 < [ <r f F O " a, [3,4] [7,8]

q 9 9<tqyD Jaf_[, g, FN <t FNB < t I q y D Ja f R=. +$, GL B f [ 7{ 7 η f z E, ~1 I +, ~ L FN <t, FNB <t f q y D Jaf i 7 13.0 (G 39.3 f ia 7 34.2), ψ 9 ψ h FN <t 9 X 7 47.5 (G 40 X a 59) 9 59.7 (G 24.3 X 170 H a 38.8). B 1 H (38<E&>WN V a 4a 9 b, FN 9 FNB <tf1p$ {. Ga b, I+B, 3 <tf$ { v: E K {<Vj,, FN <tf}u>wh FNB <ti l, g,g FN <t\$ ", <r\ η OOZ ohf O"aM_y. ~1 I+B, FN <t f η 6Z ( wi.x ' η b ), 9<t\$ 1< 3 Z5f& {<, E ' T { Vj, a 4c M); FNB <t vis f}æ η \' o ze, <t$ { f}u> WGh Qil, zi} {, a 4d M). GL\<t [ B, 7{7 η fze, FNB < t\ AqBf$ { : E} K {<Vj, V &\ I+B, <t{ (2aZ5}u, a 5a M). FN <t GLV\Z5f η, V&w~ I+, AqBf$ { 5T & {<i, a 5b M). ^ <t V \ Z 5 f η ", H K \ h O OZ 2.3 [3,4] l 45 o foh T, [ <r\mif 6O"a [8]; <t ~ I+B, η QF6Z, $ ", \R L η/γ If H O> 0gC D ~, F f <rk & Æ η/γ oh!b"a, _y<t T & {<. GL η f `0 l", = \{ 3 7Z5f Oj D+, a 5c M); f Z >~ f Oj D, a 5d M). a 6a, I+B FN <tmaq4+$ { zff( r. Ga b, { zv\ 5f<r, g <r, V \L η/γ oh I (Zv n L o 1 -), g x 1 m $7 η/γ oh,<r 8L F o I, η, 9<t1p$ D fifr=. AqB FN <t$ 4+{ z(2a7z5f<r, a 6b 9 c M), g>4k M7\a 5c f{ (2aZ5 N<rf R=. a 6c s{k )7$ 1< F f<r& η/γ oh f " a t, ~ m A q4 +, A qb<t4 +{ z 97)K <r, gk,\r L η/γ oh If H [ 7<r"afl/. ~L FN <t, FNB <t wi 5f<r (2a (a 6d), 1 H, gov & I+B<t -S I η zei&;?1 H, I(n ~ m- : GL B H 8LOhu>f R l<, P r Le H [?\ oo. =M, FNB <t \ o_ f B K H R of_, P fi H ~<tm 9fJ. L ;s0o# z [25] 4 Fig.4 Fractographs of the FN and FNB alloys (a) FN, as (b) FNB, as (c) FN, as (d) FNB, as

l2e dk g : B Fe Ni M:r d p7 o Td? L ;s{ pae# z 5 Fig.5 Fractographs of the FN and FNB alloys charged with hydrogen (a) FNB, as (b) FN, as (c) FN, as (d) higher magnification of Fig.5c, FN, as L 0! P;s# z Æye' q 6 Fig.6 Microstructures near the fracture of the FN and FNB alloys after treatment (a) FN, uncharged H (b) FN, charged H (c) FN, charged H (d) FNB charged H 171

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