athmani moussa | University Mohamed Khider of Biskra, Algeria (original) (raw)
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CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council)
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e-journal of Surface sciences and Nanotechnology, 2011
Gaseous carburizing effects on improvement of performance of a new grade hot working tool steel c... more Gaseous carburizing effects on improvement of performance of a new grade hot working tool steel close to as either chromium AISI H11/H13 are investigated. Such treatments are performed at 930 • C for various processing times. Formed layers that are characterized by their basic properties (i.e. thickness, depth, formed phases, hardness distributions, carbon/carbides distributions and redistribution of alloys in the carburized layers) show a close dependence of both time-temperature process and chemical composition of material. Test results indicate that retained austenite amount act to improve significantly the wear resistance of components despite their relatively lower hardness. In addition, it is addressed that performance and productivity of the as-new material could be extensively enhanced when the above treatment is used. Metallurgical evaluations are carried out using metallographic techniques, optical, scanning electron microscopy equipped with an energy-dispersive X-Ray spectrometer and X-ray diffraction techniques. Mechanical properties are achieved mainly by standard hardness and wear tests.
The effects of conventional heat treatments, i.e. quenching and tempering, on the mechanical char... more The effects of conventional heat treatments, i.e. quenching and tempering, on the mechanical characteristics of non standard hot work tool steel, close to either AISI-H11/H13 are investigated. The major elemental composition differences are in carbon, silicon and vanadium. The objective of the carried heat treatments is to obtain an efficient tool performance in terms of hardness, wear resistance and mechanical strength. Experimental results allow an explanation of the surface properties depending mainly on both chemical composition and optimised preheating parameters. After austenitizing at 1050 °C for 15 min, the as-quenched steel in oil bath exhibited the fully martensitic structure (without bainite) connected to a small fraction of retained austenite and complex carbides mainly of M23C6 type. Twice tempering at 500 °C and 600 °C resulted in initiating the precipitation processes and the secondary hardness effect. As a result, carbide content amounted to 3% while the retained austenite content decreased to 0%. Accordingly, the required mechanical properties in terms of hardness and wear are fulfilled and are adequately favourable in handling both shocks and pressures for the expected tool life. Induced microstructures are revealed using optical and scanning electron microscopes. Phase compositions are assessed by means of X-ray diffraction technique while mechanical characteristics are investigated based on hardness and abrasive wear standard tests.
e-journal of Surface sciences and Nanotechnology, 2011
Gaseous carburizing effects on improvement of performance of a new grade hot working tool steel c... more Gaseous carburizing effects on improvement of performance of a new grade hot working tool steel close to as either chromium AISI H11/H13 are investigated. Such treatments are performed at 930 • C for various processing times. Formed layers that are characterized by their basic properties (i.e. thickness, depth, formed phases, hardness distributions, carbon/carbides distributions and redistribution of alloys in the carburized layers) show a close dependence of both time-temperature process and chemical composition of material. Test results indicate that retained austenite amount act to improve significantly the wear resistance of components despite their relatively lower hardness. In addition, it is addressed that performance and productivity of the as-new material could be extensively enhanced when the above treatment is used. Metallurgical evaluations are carried out using metallographic techniques, optical, scanning electron microscopy equipped with an energy-dispersive X-Ray spectrometer and X-ray diffraction techniques. Mechanical properties are achieved mainly by standard hardness and wear tests.
The effects of conventional heat treatments, i.e. quenching and tempering, on the mechanical char... more The effects of conventional heat treatments, i.e. quenching and tempering, on the mechanical characteristics of non standard hot work tool steel, close to either AISI-H11/H13 are investigated. The major elemental composition differences are in carbon, silicon and vanadium. The objective of the carried heat treatments is to obtain an efficient tool performance in terms of hardness, wear resistance and mechanical strength. Experimental results allow an explanation of the surface properties depending mainly on both chemical composition and optimised preheating parameters. After austenitizing at 1050 °C for 15 min, the as-quenched steel in oil bath exhibited the fully martensitic structure (without bainite) connected to a small fraction of retained austenite and complex carbides mainly of M23C6 type. Twice tempering at 500 °C and 600 °C resulted in initiating the precipitation processes and the secondary hardness effect. As a result, carbide content amounted to 3% while the retained austenite content decreased to 0%. Accordingly, the required mechanical properties in terms of hardness and wear are fulfilled and are adequately favourable in handling both shocks and pressures for the expected tool life. Induced microstructures are revealed using optical and scanning electron microscopes. Phase compositions are assessed by means of X-ray diffraction technique while mechanical characteristics are investigated based on hardness and abrasive wear standard tests.