Browsing by Author "Brahim Chermime, Abdelaziz Abboudi, Hamid Djebaili"

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    Characterization of Precipitates in the 18-1-1 and 18-1-1-5 High-Speed Steels During Tempering After Previous Quenching
    (2018-12-18) Brahim Chermime, Abdelaziz Abboudi, Hamid Djebaili
    In this paper the precipitates formed during the tempering after quenching (in salt bath) at temperature 1240 °C for 18-1-1 and 18-1-1-5 high-speed steels are investigated using an analytical transmission electron microscope (A-TEM). The study of this tempering is carried out in isothermal and anisothermal conditions, by comparing the results given by dilatometry and hardness. Tempering is performed in the range of 350-750 °C. Coarse primary carbides retained after heat treatment are of the V-rich MC and W-V-rich M6C types. In turn, it gives a significant influence on the precipitation of dispersive secondary carbides (M4C3 type), that is secondary hardening during tempering. The hardness peak is observed in the tempering range of 500-550 °C (66.8 HRC after a double tempering at 550 °C). It was found out that the cobalt in the concentration limited to about 5 % results in increasing the effect of the secondary hardening by 2 HRC. Between 700 and 750 °C, the impoverished phase (retained austenite) transforms on heating. In the end, in this temperature range of tempering, other more stable carbides of the M6C and M23C6 types are formed developing at the expense of the carbides M4C3 and M7C3 formed before, which then disappear.
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    Effect of Heat Treatments on the Mechanical Properties of a Form Tool
    (2018-06-25) Brahim Chermime, Abdelaziz Abboudi, Hamid Djebaili
    During the follow-up of the cutting tools in the production workshops, we noticed that the cutting tools operate in severe conditions, for this we thought to improve their mechanical characteristics and increase their yield. Two key factors influencing these tools, namely geometry and heat treatment. In this study we chose the heat treatment, from a basic fast steel form tool, after making the milling cutter in the tool shop we proceeded to a revenue treatment to remove austenite residues. The purpose of our work is to increase the machining quota of a Z80WCV 18-04-01 high speed steel mill, for this reason our study is based on the reduction of residual austenite by incomes. cumulated after prior quenching for different austenitization temperatures (1240, 1260 and 1270 °C)