The unlubricated sliding wear behaviour of austempered ductile irons

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dc.contributor.advisorAllen, Colinen_ZA
dc.contributor.authorFordyce, E Pen_ZA
dc.date.accessioned2016-09-28T18:57:12Z
dc.date.available2016-09-28T18:57:12Z
dc.date.issued1989en_ZA
dc.descriptionBibliography: pages 85-89.en_ZA
dc.description.abstractA study has been made of the unlubricated sliding wear behaviour of austempered ductile irons under conditions of sliding velocity and load. The load was varied between 0.9 and 2.8 MPa, whilst the sliding velocity range was between 0.5 and 2.0 ms⁻¹. Two commercial grades of spheroidal graphite irons, SG42 and SG60 were austempered between 250⁰C and 400⁰C. A distinction in the wear behaviour was found with metallic type wear dominating at the lower sliding velocities and an oxidative type wear being evident at the higher sliding velocities. It was however found that an increase in the load resulted in an earlier onset of the oxidative type wear regime, for a specific sliding velocity. On austempering these spheroidal graphite irons the mechanical properties as well as the sliding wear resistance increased dramatically. Furthermore, the austempered irons' outperformed a series of steels of much higher hardness by factors between 2 and 28 times under the same conditions. At the lower velocity of testing the outstanding wear resistance is attributed to the austempered iron's unique microstructure of acicular ferrite and retained austenite and a partial transformation of austenite to martensite. However, at the higher sliding velocity the exceptional wear resistance is derived from a development of an tribologically protective oxide film together with the formation of a hardened white layer. The development of the work hardened layer is linked to the high carbon in the matrix of these irons. The work hardened layer leads to a similar wear rate prevailing for all irons austempered from a specific parent iron. The synergism of variation in load, sliding velocity and wear counterface together with the effect of initial microstructure has been explain in terms of simple wear models.en_ZA
dc.identifier.apacitationFordyce, E. P. (1989). <i>The unlubricated sliding wear behaviour of austempered ductile irons</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering. Retrieved from http://hdl.handle.net/11427/21955en_ZA
dc.identifier.chicagocitationFordyce, E P. <i>"The unlubricated sliding wear behaviour of austempered ductile irons."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering, 1989. http://hdl.handle.net/11427/21955en_ZA
dc.identifier.citationFordyce, E. 1989. The unlubricated sliding wear behaviour of austempered ductile irons. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Fordyce, E P AB - A study has been made of the unlubricated sliding wear behaviour of austempered ductile irons under conditions of sliding velocity and load. The load was varied between 0.9 and 2.8 MPa, whilst the sliding velocity range was between 0.5 and 2.0 ms⁻¹. Two commercial grades of spheroidal graphite irons, SG42 and SG60 were austempered between 250⁰C and 400⁰C. A distinction in the wear behaviour was found with metallic type wear dominating at the lower sliding velocities and an oxidative type wear being evident at the higher sliding velocities. It was however found that an increase in the load resulted in an earlier onset of the oxidative type wear regime, for a specific sliding velocity. On austempering these spheroidal graphite irons the mechanical properties as well as the sliding wear resistance increased dramatically. Furthermore, the austempered irons' outperformed a series of steels of much higher hardness by factors between 2 and 28 times under the same conditions. At the lower velocity of testing the outstanding wear resistance is attributed to the austempered iron's unique microstructure of acicular ferrite and retained austenite and a partial transformation of austenite to martensite. However, at the higher sliding velocity the exceptional wear resistance is derived from a development of an tribologically protective oxide film together with the formation of a hardened white layer. The development of the work hardened layer is linked to the high carbon in the matrix of these irons. The work hardened layer leads to a similar wear rate prevailing for all irons austempered from a specific parent iron. The synergism of variation in load, sliding velocity and wear counterface together with the effect of initial microstructure has been explain in terms of simple wear models. DA - 1989 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1989 T1 - The unlubricated sliding wear behaviour of austempered ductile irons TI - The unlubricated sliding wear behaviour of austempered ductile irons UR - http://hdl.handle.net/11427/21955 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/21955
dc.identifier.vancouvercitationFordyce EP. The unlubricated sliding wear behaviour of austempered ductile irons. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering, 1989 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/21955en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentCentre for Materials Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherIron, Nodular - Fatigueen_ZA
dc.subject.otherMaterials Engineeringen_ZA
dc.titleThe unlubricated sliding wear behaviour of austempered ductile ironsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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