In this paper an effort has been made to plasma nitride the ball bearing steel AISI 52100. The difficulty with this specific steel is that its tempering temperature (∼170-200 • C) is much lower than the standard processing temperature (∼460-580 • C) needed for the plasma nitriding treatment. To understand the mechanism, effect of heat treatment on the nitrided layer steel is investigated. Experiments are performed on three different types of ball bearing races i.e. annealed, quenched and quench-tempered samples. Different gas compositions and process temperatures are maintained while nitriding these samples. In the quenched and quench-tempered samples, the surface hardness has decreased after plasma nitriding process. Plasma nitriding of annealed sample with argon and nitrogen gas mixture gives higher hardness in comparison to the hydrogen-nitrogen gas mixture. It is reported that the later heat treatment of the plasma nitrided annealed sample has shown improvement in the hardness of this steel.X-ray diffraction analysis shows that the dominant phases in the plasma nitrided annealed sample are ε (Fe 2−3 N) and γ (Fe 4 N), whereas in the plasma nitrided annealed sample with later heat treatment only α-Fe peak occurs.
In this work an effort has been made to study the effect on the performance of the plasma nitrided AISI H13 hot-forging dies and punches in two different forging service conditions –namely, fully-automatic and semi-automatic processes. The plasma nitriding is performed to increase the surface properties like –wear resistance and surface hardness of these components. After plasma nitriding the surface hardness of these materials has increased typically from ~500 HV0.01 to ~1200 HV0.01. In the plasma nitriding process high-voltage electrical energy is used to form plasma through which nitrogen ions are accelerated to impinge on the workpiece. The ion bombardment heats the workpiece, cleans the surface, and provides active nitrogen to make iron-nitride compounds. The iron-nitride compounds then diffuse to the workspace to harden the surface. In these two service conditions the plasma nitrided hot-forging dies and punches have shown typically 2.5 to 4 times increment during the performance. It is observed that the increment in the performance of the dies and punches depends on the forging service conditions, i.e., temperature of the dies and punches, shot repetition time and effective cooling of dies and punches in service conditions. Four times increment in the performance of dies and punches is found in the semi-automatic process, whereas two and half times increment in performance of dies and punches is observed in the fully-automatic process.
The goal of this study is to investigate magnetohydrodynamics varied convective stagnation point stream with a vertically extended sheet embedded in a permeable material. Warmth generation/absorption, radiation impacts, and viscous dissipation are all considered. Using the process of likeness change, the principal boundary layer equations are written and turned into nonlinear ordinary joined differential equations, and the numerical result is produced using the Runge-Kutta fourth-order approach via shooting technique. Varied physical limits have different effects, such as velocity fraction restriction, mixed convection restriction, Hartmann numeral, Prandtl numeral, permeability restriction, warm air radiation restriction, hotness generation/absorption restriction, and so on, over velocity and temperature scatterings are introduced graphically and then mathematically. The skin friction constant, in addition to Nusselt numerals, over the sheet is determined, expressed mathematically as well as introduced through tables. Fluid velocity and temperature increase with radiation restriction Ra.
Skin friction and Nusselt numeral are increasing
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