Guitar, María AgustinaBrühl, Sonia Patricia2024-12-102024-10-09https://hdl.handle.net/20.500.12272/11848High Chromium Cast Irons (HCCI) are materials widely used in industries such as mining and slurry pumping in oil extraction due to their resistance to abrasion, impact and corrosion in aggressive environments. The excellent performance of these castings is due to the combination of eutectic carbides (EC) and secondary carbides (SC) within a tough matrix, achieved by specific heat treatments that optimise the distribution and stability of the carbides. Destabilisation of the microstructure is the most used treatment for this type of material, allowing the precipitation of SC. The temperature (980°C) and time (0 to 90 min) used during the treatment will determine the size and fraction of SC, as well as the fraction of martensite and retained austenite (RA) formed during cooling. Secondary carbides were quantified using Fiji® software with high- and low-resolution SEM images. The results show that the average particle size as well as the volume fraction of SC increased as the destabilisation time increased, on the other hand, several small particles are not detected in low resolution images. We also evaluated the effect of heating rate, observing that a slower heating rate favours the precipitation and growth of SC during the heating process. These secondary carbides have direct implications on wear properties. The response to abrasive wear according to ASTM G65 with a load of 65 N and 4800 m of sliding on a HCCI containing 26 %Cr was evaluated in three different conditions, containing varying amounts of SC, RA, and martensite: as received, destabilised by zero and ninety minutes. An improvement in abrasive wear resistance was observed in the heat-treated samples, where the material with higher CS fraction and higher hardness showed the best response. On the other hand, scratch tests were performed with a diamond tip and 90 N load. The wear profile was obtained by confocal microscopy (CLSM) where cutting and ploughing was observed as an abrasive mechanism in the heat-treated samples. In the untreated samples a large plastic deformation is observed. The effect of the amount of chromium (16 % Cr and 26 % Cr) on the corrosion behaviour was evaluated by electrochemical tests using a 3.5% NaCl solution and salt spray (ASTM B117) in a 5% NaCl solution for 100 hours. Additionally, the effect of destabilisation time on corrosion resistance was evaluated with an immersion test (3.5% NaCl) for 10, 100, and 250 hours. The material with lower Cr content showed higher corrosion, even after only 10 hours of immersion.pdfeninfo:eu-repo/semantics/openAccessHigh chromium cast ironsHCCIEutectic carbidesDestabilization treatmentSecondary carbidesWearCorrosioninfo:eu-repo/semantics/bachelorThesisCur, EmmanuelNo comercial con fines académicos. Licencia Creative Commons CC BY-NC-SA