1. The study examines the evolution of δ phase in Inconel 718 alloy during isothermal compression deformation at 950°C and a strain rate of 0.005 s-1. 2. Results show the content of δ phase decreases from 8.14% to 7.05% during heating and holding, and from 7.05% to 5.14% during deformation. 3. Plate-like or needle-like δ phase spheroidizes and transfers to spherical or rod-shaped δ phase due to the effects of deformation and dissolution. In regions with the largest strain, plate-like or needle-like δ phase disappears completely.

1. 45 ¬ 12 Vol.45 No.12
2009 Í 12 1451—1455 ACTA METALLURGICA SINICA Dec. 2009 pp.1451–1455
Delta ¿ Inconel 718 δ » ¼¯ ∗
(Ô ¶ ¦ Þ± ¬ § , 110016)
¾ Inconel 718 ß Delta ³, »¾ßÑ Å¤ ¡§ Ѥ Ôµ X ­ ­ ²­¨· ÎÙÈ 950 ¥¡
¹ ¼ È 0.005 s−1 Ω Õ δ Ñ ÈÑ. Ö¸ À: Ä ÎÔ , ÚÉ º Õ É Å
°/ÝÆ δ ÑÚ¶¡Ø× , δ Ѿµ 8.14% È 7.05%; Ä º Õ δ Ѥ ·¡Ø, ¾µ 7.05% ´
È 5.14%; » ¡Ø » ¤ «¾, / δ Ѥ Ó , / δ Ñ ß È °/ÝÆ δ Ñ; Ä
µ© Þ¶, / δ ÑÚ ¶ × , °/ÝÆ δ Ñ© ² É Ú.
Inconel 718 ß, Delta ³, δ Ñ, ,Ó
¶ ° TG146.1, TG113.1 ¸º µ³ A ¸ Æ 0412−1961(2009)12−1451−05
EVOLUTION OF δ PHASE IN INCONEL 718 ALLOY
DURING DELTA PROCESS
ZHANG Haiyan, ZHANG Shihong, CHENG Ming
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016
Correspondent: ZHANG Shihong, professor, Tel: (024)83978266, E-mail: shzhang@imr.ac.cn
Supported by National Nature Science Foundation of China (No.50834008)
Manuscript received 2009–06–02, in revised form 2009–08–24
ABSTRACT Superalloy Inconel 718 is an important material used for aero–engine high temperature
turbine disks. The grain refining of Inconel 718 becomes critical because of the improvement in the
quality and reliability of aero–engine. Inconel 718 turbine disks are manufactured by multi–stage hot
deformation processes, in which the recrystallized grain grows up in next passes. Therefore, it is
difficult to obtain a uniform and refined microstructure by recrystallization refining. The δ phase in
Inconel 718 can control grain size through the strong pinning effect. Thus, the Delta process (DP) has
been applied for the forging of Inconel 718. In this paper, for the DP of Inconel 718, the evolution of δ
£
phase during isothermal compression deformation at temperature of 950 and strain rate of 0.005 s−1 ,
was studied by using optical microscope (OM), scanning electron microscope (SEM) and quantitative
X–ray diffraction (XRD) technique. The results show that spherical or rod–shaped δ phase particles
in the interior of grains precipitated in the aging treatment disappear during the heating and holding
time before deformation, and the content of δ phase decreases from 8.14% to 7.05%. Dissolution of δ
phase occurs during the deformation, and the content of δ phase decreases from 7.05% to 5.14%. The
spheroidization of plate–like or needle–like δ phase takes place due to the effect of deformation and
dissolution breakages, and the plate–like or needle-like δ phase transferrs to spherical or rod–shaped
δ phase. In the centre with the largest strain, the plate–like or needle–like δ phase disappears and
spherical or rod–shaped δ phase appears in the interior of grains and grain boundaries.
KEY WORDS Inconel 718 alloy, Delta process, δ phase, deformation, spheroidization
Inconel 718 ÒÆ¥×ɱ Ï· Õà ¨ ­ Ù ß . « À
Ø ºº. ¡¥×É§Û ¢ Õ , ¢ ¯Â Ð, Inconel 718 Ö
Ò Ë, Ã ¨ ­ Ù Inconel 718
ß , Ò ¨ ­ Ù Inconel 718 À ß℄
* ·℄¢Ý §Åß — ³ Åß ÞÔÆ 50834008 ± . Inconel 718 Ö δ Ò ± »Ó É ¡
à : 2009–06–02, ¡ : 2009–08–24 Û µ ¡± [1−3] , · Ì, Ruiz [3] Æ ¸ Inconel
«
Ü : ν , , 1981 Î , ° 718 Delta ´, Î Å » Ê ´ Æ

2. 1452 Ý ° ¥ 45 ¬
Õ¶ δ Ò, Å £ Ö, Ò ÏÚ δ Ò 32 h Æ Õ¶ δ Ò, Û×µ · Ï.
¢ÙÏ Ú Ñ × Ã×¡Ï Ú, Ѽ¿ º ½ °¢ ÛÊ ¦É 8 mm,
± δ Ò¢Ù × Ãס Áª. 12 mm Ý ¿ ª . Ï º ½ ª
Ç , ± Delta ´± ÍÒ± É ° Ì Å ÂÌ É MMS300 ª . ª ´É: ±
¸ Ü Æ ©, Ù ¸ Ü×¹. Å ´Æ ©§ , Ruiz 5 ¦/s ½ Ï Ú, Ï 180 s
[3]
» Delta ´ à ¸¡± À ÏÉ 8 Ï ± Õ º ½ º É 1.1, ×µ Î
¦É 150 200 mm Inconel 718 ß ℄, ± Í · ϱ ¿ ¨ .
¡± À ÏÉ 11 Ï ¦É 76 38 mm ¯ ℄; ª ¯ÚÕÐ , ¡± ·Í Ƴ
Dix [4]
¿ Delta ´Ã ¸¡± À ÏÉ 9 Ï ¨ ³ ª . ¼ ¿ Ò Æ¥ (OM) ³
Inconel 718 ß℄, » ÂßÆà ¸¡± À Ƴ¨ ; ¼ ¿ ¨ Ò ¥ (SEM) ³ ª δ Ò Ò
É 13 Ï ß ; Bhowal Schirra[5] Delta ª ³; ¼ ¿ Õ ¶ X Æ Æ ³ (XRD) ¶ ¿ δ
´ Gatorizing ´Ò× Ã ¸¡±À Ï Ò¿¶, δ Ò ¿¶Ò , ɸ ¶£ Ú,
11 Ï Inconel 718 ß ; ¯ [6] » XRD ¶ ´Æ Ê .
Delta ´ÊÒ ¸¡± À ÏÉ 12—14 Ï 2 ´½ ¹
¡ GH4169 « ℄. Å É Æ ©§ , Yuan À 1 É ÛÊ Æ³¨ δÒ ª
Wang [8] ¼ ¿ Ï ª Æ©¸ Delta
Liu[7]
´Ö δ Ò¡ Inconel 718 É » Ó, Æ © ³ À. Û Ê , © ¡Û°Ø , ¨
Á, δ Ò Ï Å ± Î × Ã ×¡ ¥ . ℄ ¡ δ Ò ÉË δ ¨ , δ Ò¿¶É 8.14%(Ó¶ª¶), ¡ÊÏÅ
¶ / ℄ ±/Þ¯ δ Ò (À 1b). Inconel
Å » Ö É Ò ÁÜ¬Ò º Æ ©.
Öγ γ Ò Æ γ ± ,δÒ Æ
Ö δ Ò ¢ÙÏ Ú Nb ¿¶
′′ ′
718
Inconel 718
, ª É 1020—1040 ¦ [9] . ℄ Ï Ú 950 ¦
γ ¨ ± , δ Ò Å Æ γ ¡Ê Æ¢ ­
,δ Ò ¢Ù; δ Ò ¶¢Ù¥ Å Ï Ú 980 ¦
˶ . δ Ò Æ Í ÛÏ Ú ±,
. Æ© Á » Ö Inconel 718 ¥ ÏÚ 900 ¦ , Ü Å ¡Û ¡Ûª ; Ï Ú
900 ¦ , δ Ò ± Í Æ γ ¡Ê Ó Æ [13].
[10] [11]
× Ãס ÏÚ 850 ¦. , ¡± Delta ´
¥ × Ã ×¡ ¡± À Æ © [5,8] Á,
Å ÏÚÉ 950 ¦ º ½ 0.005 s−1 , Ë¥
× Ãס, ¡±À ÏÉ ASTM12. ·Ì, ¤
ÇÅ ÏÚ 950 ¦, º ½ 0.005 s−1
Inconel 718 ª , Æ ©ª δ Ò Å »
Ö É Ò, ± É Ò Õ Delta ´ ¿ .
1 ´½ ±
¿ É ¦ 250 mm, Ú 52 mm © ¿
Inconel 718 º, ¨ ª (Ó ¶ª¶, %)
É: C 0.027, Ni 53.74, Cr 17.58, Nb 5.35, Mo 3.01, Ti
0.98, Al 0.52, B 0.0025, Si 0.009, Mn 0.07, Co 0.40,
Fe ¶.
¯ Ý º Ù §Õ Ò Ù ± ¨
. Å 1040 ¦ Ï 40 min ­ °¢ Ê
· ϱØÇ ¨ ÏÅ º² ¢
º , Ƴ¨ É © °¢ ¬¶
℄. Inconel 718 Ö δ Ò Æ¬ É 900 ¦,
℄ Ö (Al+Ti) ¿¶ ( ¡ª¶) Nb ¿¶
0.66 , Å 700—900 ¦Þ ÛÂ Æ γ ′′
γ Ò
′ [12]
. Û È, γ γ ′ ÒÂÛ
′′
·1 900 ¥
Ú 32 h ß Å²§
δ Ñ ©²
É δ Ò, Û 24 h, γ ′′ γ ′ ÒÛ · Éδ
Ò . ·Ì, ¤Ç °¢ Ê Å 900 ¦ Û ¤
Fig.1 Microstructure (a), and morphology and distribution
[7] of δ phase (b) aged at 900 for 32 h

3. 12 ͼ : Delta ²Ô Inconel 718 ÞÔ δ Ð
ÇÐ 1453
¿ Inconel 718 (Al+Ti) ¡ª¶ Nb 7.05% Ð É 5.14%, ¸Á Å » Ö δ Ò¥ ¸
¡ª¶ É 0.69( 0.66),·Ì À 1 Ö ¡Ê
, ¢Ù.
±/Þ¯ δ Ò Ü ÛÄ Å¡Ê Æ γ ′′ γ ′ À 3 Éß · Ü· Ö · Í Æ³¨ δ
Ò . Ò ª ³ À. À 3a , Ö ¶Ò
À 2 ɨ ª ´ Ï Ú 950 ¦ Ï Ù, ¥ ¸¬¶ × Ã ×¡, ¡Ê Ï Å ¶
180 s Ƴ¨ δÒ ª ³ À, Ì ¨ / ℄ δ Ò, Ñ ª §Õ ±Ë / ℄
ɪ Ä ¨ . Ö δ Ò¿¶ δ Ò Å Á²¬ ¿ ¥ ¸Á Ï×¾ , Ï×
8.14% Ð É 7.05%, ¸Á Å Ï» Ö δ §Õ ª §Õ Ë ; , ¡ÊÁ Ï Å ¬¶
Ò¥ ¸¢Ù. À 2 , Ï , ÛÊ ÖÅ ±/Þ¯ δ Ò. À 3b , / ℄ δ Ò Å
¡Ê Æ ±/Þ¯ δ Ò Û · Ø . Inconel 718 ¶ · ª¥ ¸ ¼, Ñ Å , / ℄
ÖδÒ Æ Ê Ï Ú ±, Ê Ï Ú δ Ò ÅÜ · Í¥ ¸¢Ù ¼. δ Ò Æ γ ɨ
930 ¦ , Õ δ ÒÉ / ℄ ; Ï Ú ± , Å » Ö, À × Í ± ¶ Ð δ Ò, £
1010 ¦ , Õ δ ÒÉ ±/Þ¯ ; Ï Ú Å 930— Â×ß» δ Ò. / ℄ δ Ò À Ò , »
1010 ¦ , Õ δÒ É℄ ±/Þ¯ ÖÀ×Í Èß» /℄ δ Ò, £ Å /
´ × . Å 900 ¦ Û Ê 32 h , ¡Ê Ï Å ¶
[14]
℄ δ Ò ¥ ¥Ê, ·Ì, Å /℄ δ Ò
γ ′′ γ′ Ò Ñ ±/Þ¯ δ Ò, Í ¶ º²ÌÖ, δÒ ¼Ë , /℄
ªª Ü ±/Þ¯ δ Ò Ø É¨ Õ . · Ì, Å δ Ò¥ ¼, Wang [8]
¸ Ö. Ò¡
950 ¦ Ï» Ö ¡Ê ± Õ ±/Þ¯ δ Ò¥ ±/Þ¯ δ Ò, À Ò / ℄ δ Ò Ë
¸¢Ù, ÃÛØ (À 2). Ò , Ñ ÙÇÆ É Nb ֣ŠÙÇÖ Ê
Þ Å ´ Ü Ä¬É¤ , ℄ Å Nb ÚÏ Å Ú, Ü · » Ø É / ℄ δ Ò
Â Ï Å Ã ¸ ¬ ¿, · Ì, ·ª ¢Ù ¸Ø × ². ¾ ½ [15] ¥ ℄ δ Ò Å Ê
¶±Ò , Öß· ¶ª , ´ ÜÏ Å Ù » Ö ¥ ¢Ù ¼ Ö, É Å℄ δ Ò
· ª ºÖ. Å Ï Ú É 950 ¦, º ½ É Ê · Þ Ï Å« ¡ÛÄ Í Ú Ö, Í £ Å ÒÊ Û
0.005 s−1 , º É 1.1 , δ Ò¿¶ ϲ, £ . Ò¡
, ´ ×
·2 950 ¥ Î 180 s ßŲ§
δ Ñ ©² · 3 Þ¶ Û ¶Ì Ų§
δ Ñ ©²
¤
Fig.2 Microstructure (a), and morphology and distribution Fig.3 Microstructure (a), and morphology and distribution
of δ phase (b) held at 950 for 180 s of δ phase (b) in the area between center and end

4. 1454 Ý ° ¥ 45 ¬
× ­ ¦ÒÙ, × Ê Ò ¢Ù, Û Ï ¼ ¥ .
²
À, ɸ
,  µ , £Ì¦ ¥ª ´, » Ö ¼ ¢Ù ¼
¯ , ¥ ¢Ù ¼. ·Ì, ¬¿ ± ¬ ¿, / ℄ δ Ò¥ ¸Ô , / ℄ δ
/ ℄ δ ÒÊ · « ¡ÛÄ Í ÚÖÈ¢£ Ò ¼ É ±/Þ¯ δ Ò.
Î ¢Ù ¼ É. , Å » Ö, À×Í Å 3 ²
/ ℄ δ Ò ¥ ¥Ê, Å Í º ² ¬ ¿ , ℄¡ Inconel 718 Delta ´, Æ ©ª ¸
¢Ó¶ ¸ ¦ Í ª Ù Ç [16] , ·Ì, Í ¥Ê ÏÚÉ 950 ¦, º ½ É 0.005 s−1 Ϫ
Í ± É Nb ¡ ¦ ½ , » ÖδÒ É Ò, £ × :
½ / ℄ δ Ò ¢Ù ¼. (1) Å ÏÕ , Û» Ö ¡Ê
À4É ß · Ƴ¨ δ Ò
Æ ±/Þ¯ δ Ò ÃÛ¢ÙØ , δ Ò ¿¶
ª ³ À. , ß·Å » Ö ¥ ¸ÃÛ × Ã ×¡ 8.14% Ð É 7.05%.
(À 4a), / ℄ δ ÒØ , ¡Ê ¡Û ¯ ª
» Ö, δ Ò¥ ¸¢Ù, ¿¶ 7.05%
ÚË §Õª ³ ¶ ±/Þ¯ δ Ò (À 4b). ×
(2)
Ãס ±ªÉ´ Õ , . ¢ Õ µÐ É 5.14%.
» Ö, /℄ δ Ò¥ ¸Ô ,
Á , Í Æ³Ñ Ú, ª Í Ú ¾ÛÍ Ú
(3)
/ ℄ δ Ò É ±/Þ¯ δ Ò; Å ¶ª
¢ . Å » Ö À × Í ± ¶ Â×ß» ß ·, / ℄ δ ÒÛ · Ø , ±/Þ¯ δ Òª ³
/ ℄ δ Ò£ Å ¥ ¥Ê, · Ì, / ℄ ¡Ê ¡Û.
δ Ò Ï Å ±℄ ± Þ× Ã ×¡ Á ,Á ¼ ¢Ù ¼ ¥ ¬ ¿, /℄
±È × Ãס Í , Î × Ãס ¥ ,
(4)
δ Ò¥ Ô .
Yuan Liu[7] Wang [8]
Ʃ׹ Ò
. ¦» , Å » Ö, × Ãס¡ ¸º
/¡± ¡ÛÕ Í ÚÖ , ·Ì, × Ãס
¥ Þ ÒÖ » Ú
À, Í £ È [1] Hiroaki Y, Takeshi H, Tomohisa H, Sachihiro I, Hideaki S.
/ ℄ δ Ò ¢ÙØ × ². , ß·
In: C´sar de S´ J M A, Santos A D eds., Proc 9th Int Conf
¶ª
e a
ß · / ℄ δ Ò
on Numerical Methods in Industrial Processes, Portugal:
, ¼ ¢Ù Porto, 2007: 987
[2] Zhao Y F. Master Thesis, Beijing Research Institute of
¶ ¢ÈÑ­¨ ¹ §Ì
Mechanical Electrical Technology, 1999
( « ÈÝ. , 1999)
[3] Ruiz C, Obabueki A, Gillespie K. In: Antolovich S D, Stus-
rud R W, MacKay R A, Anton D L, Khan T, Kissinger R
D, Klarstrom D L eds, Superalloys 1992, Warrendale, PA:
TMS, 1992: 33
[4] Dix A W, Hyzak J M, Singh R P. In: Antolovich S D, Stus-
rud R W, MacKay R A, Anton D L, Khan T, Kissinger R
D, Klarstrom D L eds, Superalloys 1992, Warrendale, PA:
TMS, 1992: 23
[5] Bhowal P R, Schirra J J. In: Loria E A ed, Superalloys
718, 625, 706 and Various Derivatives, Warrendale, PA:
TMS, 2001: 193
[6] Lu H J, Yao C G, Zhang K F, Jia X C. Mater Mechanical
¹¹
Eng, 2003; 27(1): 15
( Æ , ,Î « , .ÈÝ , 2003; 27(1):
15)
[7] Yuan H, Liu W C. Mater Sci Eng, 2005; A408: 281
[8] Wang Y, Zhen L, Shao W Z, Yang L, Zhang X M. J Alloys
Compd, 2009; 44: 341
[9] Schafrik R E, Ward D D, Groh J R. In: Loria E A ed,
Superalloys 718, 625, 706 and Various Derivatives, War-
·4 Þ¶ Ų§
Ñ ©²
rendale, PA: TMS, 2001: 1
δ
[10] Hu J P. PhD Dissertation, Steel Research Institute, Bei-
Fig.4 Microstructure (a), and morphology and distribution
­¨¦ ° §Ì
jing, 1999
of δ phase (b) in the center ( . , ¢ , 1999)

5. 12 ͼ : Delta ²Ô Inconel 718 ÞÔ δ Ð
ÇÐ 1455
[11] Zhao D, Chaudhury P K. In: Loria E A ed, Superalloys Warrendale, PA: TMS, 1994: 281
718, 625, 706 and Various Derivatives, Warrendale, PA: [15] Cai D Y, Zhang W H, Liu W C, Yao M, Sun G D, Chen
TMS, 1994: 303 Z L, Wang S G, Gao Y K. J Iron Steel Res, 2002; 14(6):
½ ¼ ÎÊ µÖ £½ Ä«
[12] Thomas A, El–Wahabi M, Cabrera J M, Prado J M. J 61
Mater Process Technol, 2006; 177: 469 ( , , , , , , ,
[13] Sundararaman M, Mukhopadhyay P, Banerjee S. In: Loria . ­¨§ , 2002, 14(6): 61)
E A ed, Superalloys 718, 625, 706 and Various Deriva- [16] Pan J S, Tong J M, Tian J M. Fundamentals of Material
¹¹ §ÅÈ §Å¬
tives, Warrendale, PA: TMS, 1994: 419 Science. Beijing: Tsinghua University Press, 2002: 473
[14] Desvall´es Y, Bouzidi M, Bois F, Beaude N. In: Loria E
e ( ß ­ , , . . ¢ Ò :
A ed, Superalloys 718, 625, 706 and Various Derivatives, ¯ , 2002: 473)