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The Influence of Pearlite Present in the Microstructure of GX120MnCr13 Cast Steel on Wear Resistance

Kalandyk Barbara, Zapała Renata, Sulima Iwona, Furmańczyk Piotr, Kasińska Justyna

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 4

145--156

EN

The article presents the results of metallographic and tribological tests on GX120MnCr13 cast steel that was previously subjected to heat treatment (including solution treatment from 1100°C and isothermal holding at 250, 400, and 600°C for 100 hours). The temperatures of the isothermal holding process were selected in order to reflect the possible working conditions of the cast elements that can be made of this cast steel. Wear tests were carried out under dry friction conditions using the ball-on-disc method using a ZrO2 ball as a counter-sample. The tests were carried out with a load of 5 N. The influence of the long-term isothermal holding process on the microstructure of the tested cast steel was analysed by light and scanning microscopy; however, abrasion marks were also examined using a confocal microscope. Based on the tests conducted, it was found that in the microstructures of the sample after solution treatment and samples that were held in isothermal C, the grain boundary areas were enriched in Mn and Cr compared to the areas inside the grains. Pearlite appeared condition at 250 and 400 in the sample that was heated (or held in isothermal holding) at 600°C; its share reached 41.6%. The presence of pearlite in the austenitic matrix increased the hardness to 351.4 HV10. The hardness of the remaining tested samples was within a range of 221.8-229.1 HV10. Increasing the hardness of the tested cast steel directly resulted in a reduction in the degree of wear as well as the volume, area, and width of the abrasion marks. A microscopic analysis of the wear marks showed that the dominant process of the abrasive wear of the tested friction pair was the detachment and displacement of the tested material through the indentation as a result of the cyclical impact of the counter sample.

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Influence of Pre-Hardened Gx120mn13 Cast Steel on the Tribological Properties under Technically Dry Friction

Kalandyk Barbara, Zapała Renata, Madej Monika, Kasińska Justyna, Piotrowska Katarzyna

Tribologia

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2022

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nr 3

17--24

EN

This paper presents the results of tribological tests on high manganese GX120Mn13 cast steel under technically dry friction conditions. The tests were carried out using a TRB3 ball-on-disc tribometer using a 6mm-diameter SiC ball as a counter-sample for a specimen made of GX120Mn13 cast steel containing a localised prehardening area on the test surface with a hardness of approximately 597 HV10 (the non-hardened area had a hardness of approximately 325–364 HV10). During the test, the ball travelled in a 16.68 mm diameter circle and passed through both hardening and non-hardened areas. The resulting erosion marks were assessed using an optical profilometer and scanning microscope tests, which showed that the maximum depth of erosion in the previously hardening area was 0.77 µm and was more than twice as deep as in the non-hardened areas surveyed. In contrast, the area of attrition was twice as small as in the non-hardened area located in the axis of the previously applied load and more than three times smaller, but in the area located on the side of the axis and 8.34 mm away from it. Thus, from the point of view of the abrasion resistance of GX120Mn13 cast steel, the validity of its prior hardening before the operation was confirmed.

PL

W artykule przedstawiono wyniki badań tribologicznych wysokomanganowego staliwa GX120Mn13 w warunkach tarcia technicznie suchego. Badania przeprowadzono przy użyciu tribometru TRB3 typu ball–on– disc stosując jako przeciwpróbkę kulkę z SiC o średnicy 6mm dla próbki wykonanej ze staliwa GX120Mn13 zawierającej na powierzchni badanej lokalny obszar wcześniej umocniony o twardości ok. 597 HV10 (obszar nieumocniony posiadał twardość ok 325–364 HV10). Kulka w czasie testu poruszała się po okręgu o średnicy 16.68 mm i przechodziła zarówno przez obszar umocniony, jak i nieumocniony. Otrzymane ślady wytarcia oceniano za pomocą badań wykonanych na profilometrze optycznym i mikroskopie skaningowym. Na podstawie przeprowadzonych badań wykazano, że w obszarze wcześniej umocnionym maksymalna głębokość wytarcia wynosiła 0.77 µm i była ponad dwukrotnie mniejsza niż w badanych obszarach nieumocnionych. Z kolei pole wytarcia było dwukrotnie mniejsze niż w obszarze nieumocnionym, znajdującym się w osi przyłożonego wcześniej obciążenia i ponad trzykrotnie mniejsze w porównaniu z obszarem znajdującym się z boku osi i oddalonym od niej o 8.34 mm. Tym samym, z punktu widzenia odporności na zużycie ścierne staliwa GX120Mn13, potwierdzono słuszność jego wcześniejszego umocnienia przed eksploatacją.

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Assessment of Microstructure and Mechanical Properties of the Slag Ladle after Exploitation

Kalandyk Barbara, Zapała Renata, Sobula Sebastian, Tęcza Grzegorz, Piotrowski K.

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 2

351--358

EN

The results of tests and examinations of the microstructure and mechanical properties of cast steel used for large-size slag ladles are presented. Castings of this type (especially large-size ladles with a capacity of up to 16 m3) operate under very demanding conditions resulting from the repeated cycles of filling and emptying the ladle with liquid slag at a temperature exceeding even 1600°C. The changes in operating temperature cause faster degradation and wear of slag ladle castings, mainly due to thermal fatigue.The tests carried out on samples taken from different parts/areas of the ladle (flange, bottom and half-height) showed significant differences in the microstructure of the flange and bottom part as compared to the microstructure obtained at half-height of the ladle wall. The flange and bottom were characterized by a ferritic-pearlitic microstructure, while the microstructure at the ladle half-height consisted of a ferritic matrix, cementite and graphite precipitates. Changes in microstructure affected the mechanical properties. Based on the test results it was found that both the flange and the bottom of the ladle had higher mechanical properties, i.e. UTS, YS, hardness, and impact energy than the centre of the ladle wall. Fractography showed the mixed character of fractures with the predominance of brittle fracture. Microporosity and clusters of non-metallic inclusions were also found in the fractures of samples characterized by low properties.