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

S . P á l k a – J . H a s i l – P. D o l e ž a l

Z l e p š e n í v l a s t n o s t í l i t é Cr- N i o c e l i D I N 1. 4 8 65 p ř í s a d o u i n o ku l a nt ů

L i t e ra t u ra

E va l u a t i o n o f t e n s i l e p r o p e r t i e s

[1]

In the field of hot tensile strength there was recorded slight detrimental effect of the technology. Out of the tests it is clear that the strength decrease is done at the benefit of ductile properties (tab. II). Strength decrease was the most significant for the samples poured into the isolated mould. The average value of strength was about 6% worse. The impact on plastic deformation is 16% but the spread of the results is the biggest of measured samples. For the samples poured into normal mould the strength decrease was very small but the improvement of the ductility was 36% (fig. 4).

[2]

[3]

[4]

[5]

[6]

LIN, L.; H. TAIWEN; X. YUHUA; Z. ZHILONG a kol.: Cast structure and mechanical properties of fine grained superalloy K4169 by addition of refiners [online]. [cit. 2015-07-14]. Dostupné z: http://www.tms.org/superalloys/10.7449/2004/Superalloys_2004_493_500.pdf. Development of a conventional fine grain casting process [online]. [cit. 2015-07-15]. Dostupné z: http://www.tms. org/superalloys/10.7449/1984/Superalloys_1984_3_12. pdf. STRAND DAHLE, E.: Grain Refinement of High Alloyed Steel [online]. 2011 [cit. 2015-08-17]. Norweigian university of Science and Technology. DULIEU, D.: The role of niobium in austenitic and duplex stainless steels. [online]. [cit. 2012-02-19]. Dostupné z: http://www.cbmm.com.br/portug/sources/techlib/science_techno/table_content/sub_5/images/pdfs/050.pdf. SKLENICKA, V.; L. KLOC: Creep in boiler materials: mechanisms, measurement and modelling. In: Power plant life management and performance improvement. Ed. by OAKEY, J. London: Woodhead Publishing Series in Energy, 2011. 704 s. ISBN: 9781845697266, e-Book ISBN: 9780857093806. PIEKARSKI, P.: The thermal fatigue behaviour of creep-resistant Ni-Cr cast steel [online]. [cit. 2015-07-14]. http:// www.afe.polsl.pl/index.php/en/147/the-thermal-fatigue-behaviour-of-creep-resistant-ni-cr-cast-steel.pdf.

Recenzenti | Peer-reviewers: prof. Ing. Ladislav Zemčík, CSc. Ing. Martin Dulava, Ph.D.

Aluminium China 2016 Termín konání: 12.–14. 7. 2016 Místo konání: Šanghaj, Čína Bližší informace: www.messeinfo.de/AluminiumChina-M316/Shanghai.html

AMB – mezinárodní výstava pro obrábění kovů Termín konání: 13.–17. 9. 2016 Místo konání: Stuttgart, Německo Bližší informace: www.amb-messe.de

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S l é vá re ns t v í . L X I V . k v ě te n – č e r v e n 2016 . 5 – 6

E va l u a t i o n o f t h e r m a l fa t i g u e r e s i s t a n c e Spread of the results achieved by this test is usually quite big (tab. III). Therefore the batch of values was statistically tested and one value was erased. In spite of the spread there is visible improvement of the thermal fatigue resistance recorded on the inoculated samples. The average improvement reached the value of 19% (fig. 5). Conclusion Successful use of inoculants in Cr-Ni austenitic steels requires proper production methods and checking them. It is easy to achieve grain refinement via addition of Nb but this leads to the modification of chemical composition. Use of cerium based inoculants EGR is much more complicated. Especially right deoxidation and checking of inoculants dosing is very important. The effect on the final structure is limited. The biggest impact of EGR addition was recorded in the improvement of thermal fatigue resistance which is a critical property in hot applications. Slight detrimental effect was recorded in the field of tensile strength. This is on the other hand followed by the improvement in the field of ductility. Inoculation is an effective method to improve the material properties. It is technically possible to apply this technology in the industrial range over fast customization in the plant. Small price impact is more than equalized by longer lifetime in the applications where parts face the thermal fatigue. Due to the requirement of proper foundry methods this technology supposes to be easily managed by the advanced foundries which can gain the competition advantage against low cost competitors.

56. mezinárodní slévárenská konference PORTOROŽ 2016 Termín konání: 14.–16. 9. 2016 Místo konání: Portorož, Slovinsko Bližší informace: www.drustvo-livarjev.si

METAL, NonFerMet a Recycling Termín konání: 20.–22. 9. 2016 Místo konání: Kielce, Polsko Bližší informace: www.metal.targikielce.pl

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