Incoloy A-286 為一鐵鎳基型超合金，其廣泛應用於渦輪及噴射引擊等。然而，A-286超合金雖然有其較長的應用歷史，對於A-286成型製程仍有其問題。其超合金之熱成形性質易受成份之影響，尤其以雜質元素(如：硫元素)較明顯。在此研究中，A-286合金在高溫輥壓下產生裂痕，並在仔細觀察下發現因為硫、磷、矽元素偏析在晶界造成共晶反應並產生富鈦液化相，促使材料產生沿晶斷裂之現象。同時發現有Ti(C,N)析出物在晶粒中。為了提升A-286之成形性，在合金設計中加入少許的鎂元素，同時也加入錳元素來觀察其成形性的影響。在研究中測試1050oC 及1175oC下拉伸試驗、900oC循環氧化實驗及使用OM, SEM-EDS,TEM-EDS,Auger及EPMA觀察其合金之微結構及破裂面。在結果中發現鎂元素添加在A-286中可減少富鈦液化相之現象及提升高溫下晶界延展之性質。

Incoloy A-286 is a Fe-Ni based superalloy and it is widely used in gas turbine industry, jet engines and other applications. Although A-286 has a long service history, the fabrication of A-286 is not without any challenges. The hot deformation property for this alloy is highly sensitive to its composition, especially the content of impurity such as sulfur (S). In present study, a batch of A-286 has suffered from cracking issue during rolling process at high temperature and detailed examinations have revealed that phenomena of liquation of Ti-rich phase induced by eutectic reaction with S appeared at grain boundary and caused intergranular fracture. To improve the hot deformation behaviors of A-286, alloy design has been performed with the minor addition of magnesium (Mg). Furthermore, its combined effect with manganese (Mn) has been examined. Experiments include tensile tests at 1050oC and 1175oC, cyclic oxidation at 900oC, detailed microstructure/fracture surfaces observations and composition analysis by OM, SEM-EDS, TEM-EDS, Auger, and EPMA. In conclusion, Mg addition can eliminate the phenomena of Ti-rich phase liquation, the high temperature deformation behaviours of A-286 can then be improved.

1. Incoloy A-286. Special Metals Corporation, 2008.
2. Rho, B.S., Hong, H.U. and Nam, S.W., Analysis of the intergranular cavitation of Nb-A286 alloy in high temperature low cycle fatigue using EBSD technique. Scripta Materialia, 2000. 43(2): p. 167-173.
3. Seifollahi, M., et al., The Mechanism of eta Phase Precipitation in A286 Superalloy During Heat Treatment. Journal of Materials Engineering and Performance, 2013. 22(10): p. 3063-3069.
4. OHTA Sadao, Honjo Takemitsu, A.K., and Motoda Takashi, Effect of manufacturing condition on high temperature properties of A-286 alloy. Tetsu- to- Hagane 1980. 66: p. S460.
5. Brooks, J., Effect of Alloy Modifications on HAZ Cracking of A-286 Stainless Steel. Welding journal, 1974: p. 517-523.
6. Muhmond, H.M. and Fredriksson, H., An Investigation on the Effect of S and Al on the Austenite Growth Morphology in Gray Cast Iron, Using Thermal Analysis and Etching Technique. Transactions of the Indian Institute of Metals, 2013. 66(2): p. 185-192.
7. Ma, P. and Zhu, J., Magnesium Distribution in a Nickel-Based Superalloy. Metallography, 1986. 19(1): p. 115-118.
8. Hughes, H., Precipitation in Alloy Steels Containing Chromium Nickel Aluminium and Titanium. Journal of the Iron and Steel Institute, 1965. 203: p. 1019-&.
9. Tavakkoli, M.M. and Abbasi, S.M., Effect of molybdenum on grain boundary segregation in Incoloy 901 superalloy. Materials & Design, 2013. 46: p. 573-578.
10. Wei, C.N., Bor, H.Y., and Chang, L., The influence of carbon addition on carbide characteristics and mechanical properties of CM-681LC superalloy using fine-grain process. Journal of Alloys and Compounds, 2011. 509(18): p. 5708-5714.
11. Qin, X.Z., et al., Decomposition of primary MC carbide and its effects on the fracture behaviors of a cast Ni-base superalloy. Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 2008. 485(1-2): p. 74-79.
12. Zhao, M.J., et al., Effect of boron on the microstructure, mechanical properties and hydrogen performance in a modified A286. Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 2010. 527(21-22): p. 5844-5851.
13. Hong, H.U., et al., On the Role of Grain Boundary Serration in Simulated Weld Heat-Affected Zone Liquation of a Wrought Nickel-Based Superalloy. Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science, 2012. 43A(1): p. 173-181.
14. Cutler, E.R., Wasson, A.J. and Fuchs, G.E., Effect of minor alloying additions on the carbide morphology in a single crystal Ni-base superalloy. Scripta Materialia, 2008. 58(2): p. 146-149.
15. Rho, B.S., Kim, K.J., and Nam, S.W., The effect of hold time and waveform on the high-temperature, low-cycle fatigue properties of a Nb-A286 alloy. Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science, 2001. 32(10): p. 2539-2546.
16. Xie, X., et al., Investigation on high temperature strengthening and toughening of iron-base superalloy. JOURNAL OF UNIVERSITY OF SCIENCE AND TECHNOLOGY BEIJING, 2003. 10(1): p. 44-48.
17. Kobayashi, K., et al., High-temperature fatigue properties of austenitic superalloys 718, A286 and 304L. International Journal of Fatigue, 2008. 30(10-11): p. 1978-1984.
18. De Cicco, H., et al., Creep behavior of an A286 type stainless steel. Materials Characterization, 2005. 55(2): p. 97-105.
19. De Cicco, H., et al., Microstructural development and creep behavior in A286 superalloy. Materials Characterization, 2004. 52(2): p. 85-92.
20. Rho, B.S., Nam, S.W., and Xie, X., The effect of test temperature on the intergranular cracking of Nb-A286 alloy in low cycle fatigue. Journal of Materials Science, 2002. 37(1): p. 203-209.
21. Rho, B.S. and Nam, S.W., The effect of applied strain range on the fatigue cracking in Nb-A286 iron-base superalloy. Materials Letters, 2001. 48(1): p. 49-55.
22. Seifollahi, M., et al., Effect of eta Phase on Mechanical Properties of the Iron-based Superalloy Using Shear Punch Testing. Isij International, 2013. 53(2): p. 311-316.
23. Hu, R., et al., Precipitation behavior of grain boundary M23C6 and its effect on tensile properties of Ni-Cr-W based superalloy. Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 2012. 548: p. 83-88.
24. Krol, T., Baither, D., and Nembach, E., The formation of precipitate free zones along grain boundaries in a superalloy and the ensuing effects on its plastic deformation. ACTA MATERIALIA, 2004. 52(7): p. 2095-2108.
25. Lin, Y., et al., Hot tensile deformation behaviors and fracture characteristics of a typical Ni-based superalloy MATERIALS & DESIGN, 2014. 55: p. 949-957.
26. Ping, D., et al., Grain boundary segregation in a Ni-Fe-based (Alloy 718) superalloy. MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 2007. 456(1-2): p. 99-102.
27. Sun, W.S., WR), et al., Effect of sulfur on the solidification and segregation in Inconel 718 alloy. MATERIALS LETTERS 1997. 31(3-6): p. 195-200.
28. Xie, X.S., et al., The role of phosphorus and sulfur in Inconel 718. Superalloys 1996, 1996: p. 599-606.
29. Woodford, D.A. and Bricknell, R.H., Penetration and Embrittlement of Grain-Boundaries by Sulfur and Chlorine - Preliminary-Observations in Nickel and a Nickel-Base Super-Alloy. Scripta Metallurgica, 1983. 17(11): p. 1341-1344.
30. Hippsley, C.A., Sulfur Segregation and High-Temperature Brittle Intergranular Fracture in Alloy-Steels. Acta Metallurgica, 1987. 35(10): p. 2399-2416.
31. Kameda, J., High-Temperature Brittle Intergranular Cracking in High-Strength Nickel-Alloys Undoped and Doped with S, Zr and or B .1. Crack-Growth Characteristics. Acta Metallurgica Et Materialia, 1993. 41(2): p. 517-525.
32. Thompson, R.G., Mayo, D.E., and Radhakrishnan, B., The Relationship between Carbon Content, Microstructure, and Intergranular Liquation Cracking in Cast Nickel Alloy-718. Metallurgical Transactions a-Physical Metallurgy and Materials Science, 1991. 22(2): p. 557-567.
33. Radhakrishnan, B. and Thompson, R.G., A Phase-Diagram Approach to Study Liquation Cracking in Alloy 718. Metallurgical Transactions a-Physical Metallurgy and Materials Science, 1991. 22(4): p. 887-902.
34. Tancret, F., Thermo-Calc and Dictra simulation of constitutional liquation of gamma prime (gamma') during welding of Ni base superalloys. Computational Materials Science, 2007. 41(1): p. 13-19.
35. Mousavizade, S.M., F.M.G., Torkamany, M.J., Sabbaghzadehb, J. and Abdollah-zadeha, A., Effect of severe plastic deformation on grain boundary liquation of a nickel–base superalloy. Scripta Materialia, 2009. 60(4): p. 244-247.
36. Ojo, O.A., Intergranular liquation cracking in heat affected zone of a welded nickel based superalloy in as cast condition. Materials Science and Technology, 2007. 23(10): p. 1149-1155.
37. Sijbrandij, S.J., et al., Atom probe analysis of nickel-based superalloy IN-718 with boron and phosphorus additions. Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 1998. 250(1): p. 115-119.
38. Miao, Z.J., et al., Effects of P and B addition on as-cast microstructure and homogenization parameter of Inconel 718 alloy. Transactions of Nonferrous Metals Society of China, 2012. 22(2): p. 318-323.
39. Sun, W.R., et al., Effect of phosphorus on the microstructure and stress rupture properties in an Fe-Ni-Cr base superalloy. Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science, 1997. 28(3): p. 649-654.
40. Y.S.Wang , et al., EFFECT OF SILICON ON GRAIN BOUNDARY CARBIDE PRECIPITATION AND PROPERTIES OF A COBALT FREE WROUGHTN ICK&-BASE SUPERALLOY. Superalloys 1980, 1980: p. 63-72.
41. W.R. Sun, S.R.G., Guo, J.T., Tong, B.Y., Yang, Y.S., Sun, X.F., Guan, H.R. and Hu, Z.Q., The Common Strengthening Effect of Phosphorus, Sulfur and Silicon in Lower Contents and the Problem of a Net Superalloy. TMS, 2000: p. 467-476.
42. Yoo, K.B., Kim, J.H., and Heo, N.H., Impurities Segregation to Grain Boundary Carbide Interfaces and Grain Boundaries and the Mechanism of Elevated Temperature Intergranular Cracking in Heat-resistant Steel. Isij International, 2010. 50(11): p. 1702-1706.
43. Wagman, D.D., et al., The NBS Tables of Chemical of Chemical Thermodynamic Properties. Journal of Physical and Chemical Reference Data, 1982. 11.
44. Chen, G., et al., EFFECTS OF MAGNESIUM ON NIOBIUM SEGREGATION AND IMPACT TOUGHNESS IN CAST ALLOY 718. Superalloys 1989, 1989: p. 545-551.
45. Farahat, A.I.Z., et al., Effect of hot forging and Mn content on austenitic stainless steel containing high carbon. Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 2011. 530: p. 98-106.
46. Zhu, J., Cheng, Z.Y., and Ye, H.Q., The Distribution and Morphology of Trace Mg at a Grain-Boundary in a Ni-Base Superalloy. Scripta Metallurgica, 1989. 23(9): p. 1537-1542.
47. Chen, G., et al., THE ROLE OF SMALL AMOUNTS OF MAGNESIUM IN NICKEL-BASE AND IRON-NICKEL-BASE SUPERALLOYS AFTER HIGH TEMPERATURE LONG TIME EXPOSURES Superalloys 1984, 1984: p. 611-620.
48. Hays, V., et al., Use of AES to determine low solubilities of impurities: Case of MnS in austenitic stainless steel. SCRIPTA MATERIALIA, 1998. 38(3): p. 391-398.
49. Bor, H.Y., Chao, C.G., and Ma, C.Y., The influence of magnesium on carbide characteristics and creep behavior of the Mar-M247 superalloy. Scripta Materialia, 1997. 38(2): p. 329-335.
50. Ma, P.t., Yuan, Y., and Zhong, Z., CREEP BEHAVIOR OF MAGNESIUM MICROALLOYED WROUGHT SUPERALLOYS. Superalloys 1988, 1988: p. 625-633.
51. Bor, H.C., CG ; Ma, CY, The effects of Mg microaddition on the mechanical behavior and fracture mechanism of MAR-M247 superalloy at elevated temperatures. METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 1999. 30(3): p. 551-561.
52. Li, Y.Q. and Gong, Y.H., Effects of Magnesium and Long-Term Aging on Intragranular Precipitation in Fe-Cr-Ni-Mn-Mo-V-Nb Superalloy. Journal of Materials Science, 1992. 27(24): p. 6641-6645.
53. Banerjee, K., The Role of Magnesium in Superalloys—A Review. Materials Sciences and Applications, 2011. 2: p. 1243-1255.
54. Gong, W., et al., Influence of Mg on Thermoplasticity of High-Temperature Stainless Bearing Steel Cr14Mo4. JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY, 2013. 29(12): p. 1204-1208.
55. C. S. Giggins, F.S.P., Oxidation of Ni-Cr-Al alloys between 1000oC and 1200oC. Journal of the Electrochemical Society, 1971. 118(11): p. 1782–1790.
56. Cisse, S.L., Lafont, L., Tanguy, MC, Andrieu, B.E., Influence of localized plasticity on oxidation behaviour of austenitic stainless steels under primary water reactor. JOURNAL OF NUCLEAR MATERIALS, 2013. 433(1-3): p. 319-328.
57. Al-hatab, K., et al., Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures OXIDATION OF METALS, 2011. 75(3-4): p. 209-228.
58. Evans, H.E., et al., Influence of Silicon Additions on the Oxidation Resistance of a Stainless-Steel. Oxidation of Metals, 1983. 19(1-2): p. 1-18.
59. Smith, M.A., Frazier, W.E. and B.A. Pregger, Effect of sulfur on the cyclic oxidation behavior of a single crystalline, nickel-base superalloy. Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 1995. 203(1-2): p. 388-398.
60. McVay, R.V., et al., Oxidation of Low Sulfur Single Crystal Nickel-Base Superalloys. Superalloys 1992, 1992: p. 807-816.
61. Nychka, J.A., Clarke, D.R. and G.H. Meier, Spallation and transient oxide growth on PWA 1484 superalloy. Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 2008. 490(1-2): p. 359-368.
62. André Belger, Marianne Reibold, and Paufler, P., Modulus and Hardness Change of Silicon and Sapphire Substrates by TiC/VC Multilayer Coatings. Materials Sciences and Applications, 2012. 3: p. 1-10.
63. Riedel, R., Handbook of Ceramic Hard Materials. 2004. 1.
64. J. Lacazea, P., et al., Critical Assessment Of The Fe-Ni-Ti System. Thermodynamics of alloys, 2004: p. 1-16