05. Harjoitustyöt ja kurssitutkielmat / Coursework and Term papers, Final projects

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Yliopistossa suoritettujen opintojen harjoitus- ja lopputöitä / Coursework, term papers and final projects completed at the university

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Browsing 05. Harjoitustyöt ja kurssitutkielmat / Coursework and Term papers, Final projects by Keyword "abrasion resistance"

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    Compaction of tool steels by pulsed electric current (PECS) sintering process
    (2014-06-03) Postal, Stefano; Lotta, Juho; Cura, Erkin; Kemian tekniikan korkeakoulu; Hannula, Simo-Pekka
    This study had two major purposes: the microstructural investigation of High Chromium White Iron (HCWI) sintered with Pulsed Electric Current Sintering (PECS) and the evaluation of the abrasion resistance of high chromium white iron mixed with different amounts of Hadfield Steel. The objective was to obtain dense high chromium white iron compacts with fine and uniform carbide and grain structure. The materials included in the study were gas atomized high chromium white iron (2.60 wt% C, 19.48 wt% Cr, 1.02 wt% Nb) and Hadfield steel (1.95 wt% C, 4.09 wt% Cr, 13.87 wt% Mn).The experimental procedure involved preparation and characterization of the starting powders, consolidation of the powders by pulsed electric current sintering process, and characterization of the resulting compacts. Microstructural studies were carried out to establish a relationship between processing conditions and the resulting microstructure. Abrasion testing was conducted (dry sand rubber wheel test) to investigate the effect of Hadfield additions to the wear performance of the material.The optimal sintering parameters for obtaining dense high chromium white iron included sintering the material at 1050 °C for 5 minutes, heating rate being 100 °C/min and compaction pressure 50 MPa. The resulting microstructure contained fine chromium carbides dispersed in a martensitic steel matrix. The modification of dwell time and the heating rate did not influence the microstructure to any significant degree. In the abrasion tests the high chromium white iron performed noticeably better (~20% lower weight loss) than the material mixed with Hadfield steel in the abrasion test. The performance of the Hadfield steel was only slightly worse (~7% higher wear loss) than that of the high chromium white iron.