Showing 2 results for Hardness.
A. Karimi Taheri, Kazeminezhad, A. Kiet Tieu,
Volume 4, Issue 1 (6-2007)
Abstract
Abstract: The theoretical calculation of dislocation density in different regions of a deformed
workpiece of 99.99% pure copper has been carried out using different procedures consisting of
Finite Element Method (FEM) and hardness measurement. To assess the validity of the results
pertaining to these procedures, the dislocation density is experimentally measured utilizing the
Differential Scanning Calorimetry (DSC). Comparing the predicted and experimental results, it
was found that the average error in prediction of the dislocation density by the hardness
measurement and FEM is 12% and 2.5%, respectively. Also, for further confirmation of the
evaluated dislocation density of each region of the deformed workpiece, the annealing process was
carried out and in the region of higher dislocation density, a finer grain size was observed.
H. Aghajani, M. Soltanieh, F. Mahboubi, S. Rastegari and Kh. A. Nekouee,
Volume 6, Issue 1 (3-2009)
Abstract
Abstract: Formation of a hybrid coating by the use of plasma nitriding and hard chromium electroplating on the
surface of H11 hot work tool steel was investigated. Firstly, specimens were plasma nitrided at a temperature of 550
°C for 5 hours in an atmosphere of 25 vol. % H2: 75 vol. % N2. Secondly, electroplating was carried out in a solution
containing 250 g/L chromic acid and 2.5 g/L sulphuric acid for 1 hour at 60 °C temperature and 60 A/dm2 current
density. Thirdly, specimens were plasma nitrided at a temperature of 550 °C for 5 and 10 hours in an atmosphere of
25 vol. % H2: 75 vol. % N2. The obtained coatings have been compared in terms of composition and hardness. The
compositions of the coatings have been studied by X-ray diffraction analysis. The surface morphology and elemental
analysis was examined by using scanning electron microscopy. The improvement in hardness distribution after third
step is discussed in considering the forward and backward diffusion of nitrogen in the chromium interlayer. Also, the
formed phases in the hybrid coating were determined to be CrN+Cr2N+Cr+Fe2-3N+Fe4N.
