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The role of Ti, Zr and Ce in shaping of the Cr-Ni-Nb cast steel resistance to carburising

Tęcza G., Zapała R., Kawalec M.

Archives of Foundry Engineering

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2008

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Vol. 8, iss. 3s

144--148

PL

From the centrifugally cast Cr-Ni-Nb steel pipes, specimens were cut out and subjected to carburising for 100 hours in a mixture of charcoal (90%) and Na2CO3 (10%) at the temperatures of 950 and 1150°C. The specimens were cut in direction normal to the pipe axis and were examined by optical and scanning microscopy. As a parameter describing the resistance of the examined alloy to the carburising effect, the thickness of a carburised layer was accepted. It has been observed that additions of Ti and Zr, and of Ti+Zr+Ce introduced jointly, increase the thickness of the carburised layer, while the addition of Ce improves the alloy resistance to carburising. On the alloy surface, a layer composed of oxides, mainly of chromium, silicon and iron, has been formed. Changes in the chemical composition of the surface layer were examined by scanning microscopy.

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Electrolytic extractions obtained from Cu-Zr and Cu-Ce alloys and their X-ray phase analysis

Ozgowicz W., Nawrat G.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

171-174

EN

Purpose: The aim of the investigations is the formation of electrolytic extractions from Cu-Zr and Cu-Ce model alloys containing microadditions of Zr and Ce amounting to about 0.1% by weight and their identification by X-ray diffraction analysis. Design/methodology/approach: Electrolytic extractions were obtained by the anodic dissolution of the alloys. In the X-ray analysis the comparative method was applied. Findings: The activity of anodic dissolution of the investigated alloys was determined basing on the mass of the electrolytic extraction and the time of dissolution of the alloy in solutions of the electrolytes with different chemical compositions and a different complexive effect to copper and different pH. Research limitations/implications: The qualitative X-ray phase analysis permits to identify the main intermetallic phases of the investigated alloys in a limited range, mainly due to experimental reasons. Practical implications: The results of these investigations indicate a distinct relation between the mass and the kind of the dissolved phase and the value of the electrochemical potential of the active dissolution of the alloys. Originality/value: The revealing of this relation is of practical importance in regard to the accuracy of the results of the phase and crystal analysis carried out by X-ray diffraction examination.

3

Poprawa plastyczności wlewków ciągłych poprzez modyfikację struktury za pomocą mikrododatków tytanu i boru oraz regulowane chłodzenie powierzchni

Żak A., Gawor J., Zdonek B.

Prace Instytutu Metalurgii Żelaza

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2004

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T. 56, nr 4

46-48

PL

Celem, pracy było sprawdzenie możliwości rozdrobnienia struktury krystalizacji wlewków ciągłych za pomocą mikrododatków tytanu i boru oraz dodatkowego chłodzenia powierzchni zakrzepniętego wlewka. Wyniki badań makro i mikrostruktury płaskich wlewków ciągłych ze stali BW11 oraz wlewków kwadratowych ze stali St3S wykazały, że zastosowana modyfikacja składu chemicznego stali nie wpływa w istotny sposób na strukturę krzepnięcia wlewków. Rozdrobnienie struktury uzyskano w warstwie powierzchniowej wlewków poddanych dodatkowemu chłodzeniu po wyjściu ze strefy chłodzenia wtórnego.

EN

The aim of this paper was to check the possibility of refining the crystallisation structure of continuous cast billets by applying titanium and boron microadditives and additional cooling of solidified cast billet surface. The results of testing the macro- and micro-structure of BW11--steel continuous cast flat billets and St3S-steel square billets showed that the applied modification, in the chemical constitution of steel did not affect substantially the billet solidification structure. The structure refinement was obtained on surface layers of the billets that were subject to additional cooling after leaving the secondary cooling zone.