The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform
Thomas Lubben - One of the best experts on this subject based on the ideXlab platform.
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End quench hardenability test for gas Quenched steels
Strojarstvo, 2011Co-Authors: Darko Landek, Božidar Liscic, Tomislav Filetin, Thomas LubbenAbstract:Hardenability is usually characterized by the Jominy End-Quenched test. For steel grades Quenched in oil or water this test is enough selective, and for them a good fixed correlation between cooling time from 800 to 500 oC (t8/5) and the distance from the Quenched End can be established. For steel grades of high hardenability, the Jominy test is not enough selective and sensitive. To establish hardenability for these steels a new hardenability testing method with the modified Jominy test specimen has been proposed after initial investigations at Stiftung Institut fur Werkstofftechnik at University of Bremen. The proposed method is based on the high pressure gas End-quenching of cylindrical specimen with variations of kind of gas, pressure and its velocity to achieve more gradual decrease of cooling rates along the specimen and to make the hardenability test more selective with a broader range of lower cooling rates. The conducted experiments and the heat transfer simulation of cooling curves at different locations in the End-Quenched probe gives possibilities for determination of cooling time t8/5 at different distances from the Quenched End, for set quenching conditions. In addition, from the conducted End-Quenched tests and simulation results, the relation between hardness distribution and the cooling times t8/5 has been established for tested quench conditions.
Božidar Liscic - One of the best experts on this subject based on the ideXlab platform.
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End quench hardenability test for gas Quenched steels
Strojarstvo, 2011Co-Authors: Darko Landek, Božidar Liscic, Tomislav Filetin, Thomas LubbenAbstract:Hardenability is usually characterized by the Jominy End-Quenched test. For steel grades Quenched in oil or water this test is enough selective, and for them a good fixed correlation between cooling time from 800 to 500 oC (t8/5) and the distance from the Quenched End can be established. For steel grades of high hardenability, the Jominy test is not enough selective and sensitive. To establish hardenability for these steels a new hardenability testing method with the modified Jominy test specimen has been proposed after initial investigations at Stiftung Institut fur Werkstofftechnik at University of Bremen. The proposed method is based on the high pressure gas End-quenching of cylindrical specimen with variations of kind of gas, pressure and its velocity to achieve more gradual decrease of cooling rates along the specimen and to make the hardenability test more selective with a broader range of lower cooling rates. The conducted experiments and the heat transfer simulation of cooling curves at different locations in the End-Quenched probe gives possibilities for determination of cooling time t8/5 at different distances from the Quenched End, for set quenching conditions. In addition, from the conducted End-Quenched tests and simulation results, the relation between hardness distribution and the cooling times t8/5 has been established for tested quench conditions.
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system for process analysis and hardness prediction when quenching axially symmetrical workpieces of any shape in liquid quenchants
Materials Science Forum, 2010Co-Authors: Božidar LiscicAbstract:A new Temperature Gradient System has been designed for practical use when quenching real workpieces in any kind of liquid quenchants. The main hardware component of the system is a cylindrical probe of 50 mm Dia. × 200 mm assembled with three thermocouples, and the tem-perature data acquisition unit for automatic drawing of cooling curves. The accompanying software-package consists of three modules: The first one for calculation of the heat transfer coefficient, the second one for quenching process analysis by graphical presentation of different thermodynamic functions, and the third one for hardness distribution prediction on the axial section of axially-symmetrical workpieces of any complex shape. The hardness prediction 2-D program is based on a Finite Volume Method, by which cooling curves in every particular point of the axial workpiece section are calculated, and cooling times from 800 °C to 500 °C (t8/5) determined. Using the known relation between the cooling time (t8/5) and the distance from the Quenched End of the Jominy spe-cimen, for the relevant steel, the hardness can be predicted, at once, in every particular point of the axial workpiece section, which is the unique feature of this system. The system itself is designed to: record, evaluate and compare real quenching intensities during the whole quenching process, when different liquid quenchants with different conditions are used, and different quenching techniques have been applied.
Darko Landek - One of the best experts on this subject based on the ideXlab platform.
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End quench hardenability test for gas Quenched steels
Strojarstvo, 2011Co-Authors: Darko Landek, Božidar Liscic, Tomislav Filetin, Thomas LubbenAbstract:Hardenability is usually characterized by the Jominy End-Quenched test. For steel grades Quenched in oil or water this test is enough selective, and for them a good fixed correlation between cooling time from 800 to 500 oC (t8/5) and the distance from the Quenched End can be established. For steel grades of high hardenability, the Jominy test is not enough selective and sensitive. To establish hardenability for these steels a new hardenability testing method with the modified Jominy test specimen has been proposed after initial investigations at Stiftung Institut fur Werkstofftechnik at University of Bremen. The proposed method is based on the high pressure gas End-quenching of cylindrical specimen with variations of kind of gas, pressure and its velocity to achieve more gradual decrease of cooling rates along the specimen and to make the hardenability test more selective with a broader range of lower cooling rates. The conducted experiments and the heat transfer simulation of cooling curves at different locations in the End-Quenched probe gives possibilities for determination of cooling time t8/5 at different distances from the Quenched End, for set quenching conditions. In addition, from the conducted End-Quenched tests and simulation results, the relation between hardness distribution and the cooling times t8/5 has been established for tested quench conditions.
Tomislav Filetin - One of the best experts on this subject based on the ideXlab platform.
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End quench hardenability test for gas Quenched steels
Strojarstvo, 2011Co-Authors: Darko Landek, Božidar Liscic, Tomislav Filetin, Thomas LubbenAbstract:Hardenability is usually characterized by the Jominy End-Quenched test. For steel grades Quenched in oil or water this test is enough selective, and for them a good fixed correlation between cooling time from 800 to 500 oC (t8/5) and the distance from the Quenched End can be established. For steel grades of high hardenability, the Jominy test is not enough selective and sensitive. To establish hardenability for these steels a new hardenability testing method with the modified Jominy test specimen has been proposed after initial investigations at Stiftung Institut fur Werkstofftechnik at University of Bremen. The proposed method is based on the high pressure gas End-quenching of cylindrical specimen with variations of kind of gas, pressure and its velocity to achieve more gradual decrease of cooling rates along the specimen and to make the hardenability test more selective with a broader range of lower cooling rates. The conducted experiments and the heat transfer simulation of cooling curves at different locations in the End-Quenched probe gives possibilities for determination of cooling time t8/5 at different distances from the Quenched End, for set quenching conditions. In addition, from the conducted End-Quenched tests and simulation results, the relation between hardness distribution and the cooling times t8/5 has been established for tested quench conditions.
Alan Lawley - One of the best experts on this subject based on the ideXlab platform.
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effect of porosity on the hardenability of p m steels
International Journal of Powder Metallurgy, 2002Co-Authors: Suleyman Saritas, R. D. Doherty, Alan LawleyAbstract:Pores in sintered steels influence their thermal response. Cooling in the Jominy End-quench test was simulated by means of a three-dimensional finite difference model. Porosity levels of 2.5v/o, 5v/o, 10v/o, 15v/o and 20v/o were simulated by introducing randomly selected points treated as cubic pores. The model predicts that in the presence of pores, cooling rate is lowered significantly. The second simulation was a one-dimensional model of the cooling of a Jominy bar along its axis and the decrease in thermal diffusivity was calculated as a function of porosity. The decrease in thermal conductivity, is ≥1/(1-e) 2 where e is the fractional porosity and is larger than the decrease in thermal diffusivity. Simulation results support the experimental thermal conductivity measurements reported in the literature. Instrumented Jominy tests were carried out on three sintered P/M steels with porosity levels of 7 to 16v/o by means of thermocouples mounted along the axis of the Jominy bar at distances of 5, 25, 45 and 65mm from the water-Quenched End. A wrought (pore-free) SAE 4150 steel was used as a baseline reference. The experimental data show that the sintered P/M steels with porosity levels >10v/o cool faster than pore-free SAE 4150 steel, in contradiction to the prediction of the model. This is attributed to the penetration of water into the inter-connected pores which increases the cooling rate of the sintered P/M steels.
