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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Direkt släckning efter uppslag

Ahlin Heikkinen, Daniel, Holmberg-Kasa, Jacob January 2019 (has links)
Målet med denna undersökning är att minska energiförbrukningen vid framställning av gjutna detaljer i austenitiskt manganstål. Detta görs genom att undersöka om det är materialmässigt möjligt att göra förändringar som förkortar framställningsprocessen av de gjutna detaljerna medan snarlika materialegenskaper bibehålls. Den processförändring som undersöks är att slopa upplösningsbehandlingen under framställningsprocessen genom att istället släcka den gjutna detaljen direkt efter uppslag från gjutform. Konkret innebär detta att detaljen slås upp och släcks vid ett tidigare och tidsbestämt skede. Detta tillvägagångssätt kallas inom metallindustrin för direkt släckning och appliceras idag på andra legeringar och tillverkningsprocesser.För att undersöka om det är materialtekniskt möjligt att genomföra denna förändring i framställningsprocessen tas provkroppar fram. Dessa provkroppar är av en förbestämd geometri och tas fram under kontrollerade förutsättningar. Av totalt nio provkroppar släcks sex provkroppar direkt medan tre genomgår upplösningsbehandling där de senast nämnda används som referenser. Provkropparna undersöks med metoder så som mikroskopi och hårdhetsmätning för att bestämma de relevanta materialegenskaperna i provkropparna. Undersökningen visar antydningar på att det är möjligt att införa direkt släckning. Detta eftersom kornstorlek och karbidandelar inte skiljer sig nämnvärt mellan direkt släckta och värmebehandlade prover som har undersökts i denna studie. Men för ett mer definitivt fastställande behövs fortsatta studier. / The aim of this study is to reduce the energy consumed during manufacturing of parts in manganese steel. This is done by determining the possibility to make changes that shortens the production process of the castings while keeping the material properties similar. The process change that is studied is to see if it is possible to skip the heat treatment process by quenching directly after shake out of the casting. This means that the casted product needs to be shaken out and quenched at an earlier and more specific time. This process is known in the metal industry as direct quenching and is by the time of writing applied on different alloys and manufacturing processes.To determine the possibility to make the aforementioned changes to the casting process, taking the material properties into account, sample bodies are created. These sample bodies are of a predetermined geometry and are manufactured under controlled circumstances. From a total of nine sample bodies six are directly quenched and three are put through a heat treatment process, the later mentioned bodies are used as references. The sample bodies are studied with methods such as microscopy and hardness testing. In this study there are indications that it is possible to introduce direct quencing in the production of details made of austenitic manganese steel. This is because the difference in grain size and fraction of carbides is small between the direct quenched and the heat treated samples in this study. Nevertheless, further studies needs to be made to make a more definitive conclusion.
2

Effects Of Heat Treatment And Chemical Composition On Microstructure And Mechanical Properties Of Hadfield Steels

Alyaz, Serhat 01 December 2003 (has links) (PDF)
The aim of this thesis is to investigate the effects of Mn content and alloying additions such as Cr and Mo, and various heat treatment procedures on both microstructure and mechanical properties of austenitic manganese (Hadfield) steels. For this purpose, steels with two different Mn content were considered (12-14 Mn, 16-18 Mn). First, five different heat treatment procedures were applied to the as-cast 12-14 Mn specimens to decide the procedure resulting the optimum tensile properties. Then, the specimens having various amounts of Mn, Cr and Mo were cast and heat-treated to investigate the effect of alloy modifications on austenitic manganese steels. Optical and scanning electron microscopies were used for microstructural investigation. To determine the mechanical properties, tensile tests and hardness tests were carried out. In addition to correlation between microstructure and mechanical properties, ultrasonic velocity measurements were also done. The results show that both composition and heat treatment affect the performance of hadfield steels extensively, and these changes also affect the propogation velocity of the ultrasonic waves.

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