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J. Zýka – I. Andršová – J. Málek – B. Podhorná – A. Joch –K. Hrbáček Vliv mikrostruktury na mechanické vlastnosti niklové superslitiny...

O D B O R N É R ECEN ZOVA N É ČL Á N K Y

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ZÝKA, J. a kol.: Vliv operace HIP na pórovitost a mechanické vlastnosti niklové superslitiny MAR-M-247, In: Slévárenské dny 2014, Brno. [4] ZÝKA, J. a kol.: Mechanical properties and microstructure of large IN713LC nickel superalloy castings, MATEC Web of Conferences14, 21004 (2014), Eurosuperalloys 2014. [5] BOR, H. Y. a kol.: Elucidating the effects of solution and double ageing treatment on the mechanical properties and toughness of MAR-M247 superalloy at high temperature, Materials Chemistry and Physics, 2008, 109, 334–341. ISSN: 0254-0584. [6] MILENKOVIC, S. a kol.: Effect of the cooling rate on microstructure and hardness of MAR-M247 Ni-based superalloy. Materials Letters, 2012, 73, 216–219. ISSN: 0167-577X. [7] RETTBERG, L. H.; M. TSUNEKANE; T. M. POLLOCK: Rejuvenation of nickel based superalloys GTD 444 (DS) and RENÉ N5 (SX). In Superalloys 2012: International Symposium on Superalloys, TMS, 2012, s. 341–349. [8] KARAMCHED, P. S.; A. J. WILKINSON: High resolution electron back-scatter diffraction analysis of thermally and mechanically induced strains near carbide inclusions in a superalloy. Acta Materialia, 2011, 59, 263–272. ISSN: 1359-6454. [9] NYE, J. F.: Some geometrical relations in dislocated crystals. Acta Metallurgica, 1953, 1, 153–162. [10] ZÝKA, J. a kol.: Mechanical properties and microstructure of IN713LC nickel superalloy castings. In Metal 2013: 22nd International Conference of Metallurgy and Materials. Ostrava: TANGER, 2013. [11] LAVAKUMAR, A.: Strain hardening behaviour of a Nickel based superalloy SUPERCAST 247A. International Journal of Scientific & Engineering Research, 2013, 4(8), 1914–1920. ISSN 2229-5518. Recenzenti | Peer-reviewers: prof. Ing. Ladislav Zemčík, CSc. prof. RNDr. Ludvík Kunz, CSc.

the plastically rigid inclusion during mechanical deformation. Therefore we can conclude that carbide particles are an obstacle for dislocation motion. These carbides are brittle in nature. Since polycrystalline castings without directional microstructure are investigated, we can assume, that enough grains with <100> axis parallel to tensile direction are present. Therefore we can assume that long needle-like carbides crack first during tensile loading in plastic region; therefore more carbides mean earlier fracture. Strain hardening is connected with obstacles for dislocation movement. Some researchers [11] correlated γ’ particles size with strain hardening, which is not probably our case. In our case, it can be a result of smaller grain size and dendrite arm spacing resulting from higher cooling speed during solidification. Grain boundaries and interdendritic regions are also obstacles for dislocation motion, especially when decorated by carbides. Further investigation is needed to gain closer insight in observed differences in strain hardening of the MAR-M-247 cast nickel superalloy. Conclusions MAR-M-247 nickel superalloy castings with different weight were investigated. Room temperature tensile strength of MAR-M-247 is superior to IN713LC properties, plastic properties are on the opposite inferior. It was shown, that room temperature tensile properties are directly influenced by castings microstructure and thus solidifying and cooling conditions. Rupture strength is strongly correlated with elongation, hardness, grain size, and carbide fraction. Long needle-like carbides crack first during tensile loading in the plastic region; therefore more carbides mean earlier fracture. It is probable that carbides act as obstacle for dislocation movement. Acknowledgements This research was sponsored by the Czech Ministry of Industry and Trade, programme TIP, project FR-TI4/030.

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7. 3. 2017 ve Slévárnách Třinec, a. s. 16. seminář Cí l e m s e m i ná ř e j e z v e ř e j n ě n í v ý s l e d k ů r o č n í p rá c e t ý m u s e d m i č e s k ý c h s l é v á r e n. B u d e p ř e d s t a v e n n á k l a d o v ý m o d e l u r č e ný k o p t i m a l i z a c i t e p e l n é h o z p ra co v á n í o c e l o v ý c h o d l i t k ů. P o s o u ze ny b u d o u r ů z n é t e c h n o l o g i e n á k l a d o v o s t i o d d ě l o v á n í n á l i t k ů a v n e p o s l e d n í ř a d ě i f i n a n č n í n á r o č n o s t b r o u š e n í o d l i t k ů. I nfo r m o v á n o b u d e r o v n ě ž o d a l š í c h p ra c í c h ř e š e ný c h v P R OJ EK T U X V I I . B l i ž š í i n f o r m a c e : M g r. F ra nt i š e k U r b á n e k , s l e v a r e n s k a @ v o l ny.c z , w w w.s l e v a r e n s k a .c z O d b o r ný g a ra n t s e m i n á ř e : d o c . I n g . Vá c l a v K a f k a , CS c .

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