In this scientific paper it is presented the statistical analysis of the experimental data obtained by the study of the influence of the cutting parameters exerted in end-milling process on the surface roughness. The surface roughness parameter is measured in the cutting feed direction and against it. The parameters of the cutting process, the number of levels and their values were established. Based on these parameters, the research was designed on a complete factorial experiment, randomized with seven blocks. The surface roughness values were measured using a roughness tester. The research method used involved the Romanovski test. The aim of this test was to identify the data affected by aberrant errors, to remove them from the samples and then to repeat the tests for the remaining data strings until all values met the conditions imposed by the test.

This study investigated the microstructure and high temperature oxidation properties of Fe-25Cr-20Ni-1.5Nb, HK30 alloy manufactured by metal injection molding (MIM) process. The powder used in MIM had a bi-modal size distribution of 0.11 and 9.19 μm and had a spherical shape. The initial powder consisted of γ-Fe and Cr23C6 phases. Microstructural observation of the manufactured (MIMed) HK30 alloy confirmed Cr23C6 along the grain boundary of the γ-Fe matrix, and NbC was distributed evenly on the grain boundary and in the grain. After a 24-hour high temperature oxidation test at air atmospheres of 1000, 1100 and 1200°C, the oxidation weight measured 0.72, 1.11 and 2.29 mg/cm,2 respectively. Cross-sectional observation of the oxidation specimen identified a dense Cr2O3 oxide layer at 1000°C condition, and the thickness of the oxide layer increased as the oxidation temperature increased. At 1100°C and 1200°C oxidation temperatures, Fe-rich oxide was also formed on the dense Cr2O3 oxide layer. Based on the above findings, this study identified the high-temperature oxidation mechanism of HK30 alloy manufactured by MIM.