Faculty Publications

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Investigation of influence of medium ph and sulfate ion concentrations on corrosion behavior of magnesium alloy ZE41
(Allerton Press Inc., 2014) Dinodi, N.; Nityananda Shetty, A.
Magnesium alloys have emerged as potential structural materials with all capabilities to even replace close contenders; aluminium alloys in weight-critical applications. High susceptibility to corrosion being the only limitation, corrosion of magnesium alloys continues to gather much attention among the material scientists worldwide. ZE41 is one such alloy of magnesium which is increasingly gaining importance as automobile and aerospace material. In the present study the influence of the medium pH and sulfate ion concentrations on the corrosion behavior of magnesium alloy ZE41 has been investigated using electrochemical techniques like the Tafel extrapolation and electrochemical impedance spectroscopy (EIS). The tests have been carried out in a range of conditions, with gradually varying pH and sulfate ion concentration. The morphology and composition of the corroded alloy surface have been determined by the scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) analysis, respectively. The recorded results reflect a trend of a higher corrosion rate associated with a higher sulfate concentration at each pH and with a lower pH at each sulfate concentration. © 2014 Allerton Press, Inc.
Effect of working parameters on the surface integrity in cryogenic diamond burnishing of 17-4 PH stainless steel with a novel diamond burnishing tool
(Elsevier Ltd, 2019) Sachin, B.; S, N.; Dupadu, D.
The productivity of the components is adversely affected by the poor surface integrity characteristics as a consequence of the generation of high temperature in the burnishing zone. The abundant use of conventional lubricants causes environmental pollution and health problems. To overcome these issues, cryogenic cooling has been used across the world to reduce the temperature generated in the burnishing zone. It is well known that most of the accidents which involve aero engines have revealed that the reason for this may be due to the failure of the first stage of compressor blades. Hence aerospace material, 17-4 precipitation hardenable (PH) stainless steel can be used in aero engines to minimize the failure occurring due to foreign object damage. In the present study, the effect of cryogenic diamond burnishing on the surface integrity characteristics such as surface roughness, surface hardness, surface morphology, surface topography, subsurface microhardness, and residual stress of 17-4 pH stainless steel have been investigated with a novel diamond burnishing tool and also it has been related to dry and minimum quantity lubrication (MQL) environments. From the experimental results of diamond burnishing process, surface roughness was observed to be reduced by 33%–50%, 34%–51% and 25%–40% in the cryogenic cooling environment in contrast with MQL and dry environments. Similarly, the surface hardness improvement in a cryogenic cooling environment was found to be 5%–7%, 6%–10%, and 6%–9%, in comparison with MQL and dry environments respectively. © 2019 The Society of Manufacturing Engineers
Precision manufacturing of turbine wheel slots by trim-offset approach of WEDM
(Elsevier Inc., 2021) Sharma, P.; Dupadu, D.; Narendranath, S.
The present study aims to precisely manufacture the turbine wheel slot using a novel trim-offset approach of wire-electrical-discharge-machining (WEDM) in order to overcome the challenges of a conventional broaching process. Two dimensional model of turbine wheel slot is prepared in ‘ELCAM’ software to generate the computer-numerical-control (CNC) code of fir-tree-profile geometry. The experimental plan based on a trim-offset approach is executed to minimize the thermal damage and to improve the surface fatigue strength, which is most desirable for a long operating life of the jet engine. An average cutting speed of ~1.5 mm/min is observed for rough-cut and ~5 mm/min for trim-cut operation. Six categories of wires are used to manufacture the turbine wheel slots without any wire breakage and gap-short issue. The fabricated profile slots have demonstrated an average roughness (Ra) of 0.65 ?m, profile accuracy within ±5 ?m, minimum hardness alteration (34.87 Hv), and negligible recast layer (<5 ?m) using B-150 wire and fulfilled the essential requirements of the gas turbine industries. Compared to wire-electrochemical-machining (WECM), WEDM trim-offset approach is quite advantageous and should be beneficial for the researchers working in ‘Precision machining of aerospace materials’. © 2021 Elsevier Inc.

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