Browsing by Author "Sharma, S.S."

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Combined effect of multidirectional forging and heat treatment on erosion and corrosion behaviour of the Mg-Zn-Mn alloys
(Korean Society of Mechanical Engineers, 2024) Anne, G.; Hegde, A.; Kudva, S.A.; Sharma, P.; Kumar, P.; Matapati, M.; Ramesh, S.; Sharma, S.S.
Multidirectional forging (MDF) was successfully applied to the Mg-4Zn-1Mn alloy for five passes at 300 °C. The grain size of 5 pass MDF processed samples reached 18 ± 3 µm from 256 ± 6 µm, and ?-Mg, MgZn2 and MnZn13 peaks were observed. Further MDF processed samples were solution treated (ST) at 300 °C for 2 h and quenched in SAE 20W40 oil and followed by artificial ageing (A) at 170 °C for four different timings including 1.5 h, 2 h, 2.5 h and 3.5 h respectively. The peak hardness of 219 Hv (5 pass MDF + H sample) was found in 2h artificial ageing which is 3.1 times higher compared to counterpart homogenised samples. Improvement of mechanical properties was attributed to smaller grain size and precipitation strengthening as well as distribution of the secondary phases. The combined effect of MDF and heat treatment was analysed using solid particle erosion tests at 30° and 90° impact angles using alumina. It was observed that higher impact angle (90°) had more erosion rate in all conditions and 5 pass MDF + H samples exhibited better erosion (0.0001 mg/g) due to higher hardness. On the other hand, polarisation and electrochemical impedance spectroscopy measurements were used to assess the alloys’ corrosion behaviour. The 3 pass MDF + H sample was found to have a corrosion rate of 0.0235 mm/y, which is two times lower than the counterpart 3 pass MDF processed samples and sixteen times lower than the homogenised sample (0.3838 mm/y). This was primarily due to the secondary phases’ better distribution and smaller grain size. © The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature 2024.
Surface Improvement of Shafts by Turn-Assisted Deep Cold Rolling Process
(2016) Prabhu, R.; Sharma, S.S.; Jagannath, K.; Kumar, K.; Kulkarni, S.M.
It is well recognized that mechanical surface enhancement methods can significantly improve the characteristics of highly-stressed metallic components. Deep cold rolling is one of such technique which is particularly attractive since it is possible to generate, near the surface, deep compressive residual stresses and work hardened layers while retaining a relatively smooth surface finish. In this paper, the effect of turn-assisted deep cold rolling on AISI 4140 steel is examined, with emphasis on the residual stress state. Based on the X-ray diffraction measurements, it is found that turn-assisted deep cold rolling can be quite effective in retarding the initiation and initial propagation of fatigue cracks in AISI 4140 steel. � The Authors, published by EDP Sciences, 2016.
Surface Improvement of Shafts by Turn-Assisted Deep Cold Rolling Process
(EDP Sciences edps@edpsciences.com, 2016) Prabhu, R.; Sharma, S.S.; Jagannath, K.; Krishna Kumar, K.; Kulkarni, S.M.
It is well recognized that mechanical surface enhancement methods can significantly improve the characteristics of highly-stressed metallic components. Deep cold rolling is one of such technique which is particularly attractive since it is possible to generate, near the surface, deep compressive residual stresses and work hardened layers while retaining a relatively smooth surface finish. In this paper, the effect of turn-assisted deep cold rolling on AISI 4140 steel is examined, with emphasis on the residual stress state. Based on the X-ray diffraction measurements, it is found that turn-assisted deep cold rolling can be quite effective in retarding the initiation and initial propagation of fatigue cracks in AISI 4140 steel. Â© The Authors, published by EDP Sciences, 2016.
Turn-assisted deep cold rolling: An innovative manufacturing method for the improvement of fatigue life
(Research India Publications subscription@ripublication.com, 2015) Prabhu, P.R.; Sharma, S.S.; Kulkarni, S.M.; Gowrishankar, M.C.
It is well recognized that mechanical surface enhancement methods, such as shot peening, laser shock peening, roller burnishing and deep cold rolling can significantly improve the fatigue performance of highly-stressed metallic components. Deep cold rolling is particularly attractive since it is possible to generate, near the surface, deep compressive residual stresses and work hardened layers while retaining a relatively smooth surface finish. In this paper, the effect of turn-assisted deep cold rolling on the fatigue behavior of AISI 4140 steel is examined. In the present study, the parameters which have significant effect on turn-assisted deep cold rolling process are identified. Fatigue experiments are performed using rotating beam fatigue testing machine. The data is plotted as cyclic stress versus number of cycles to failure. It is found that ball diameter and rolling force has significant influence on fatigue performance of 4140 steel and it exhibits well-defined fatigue limit below which continued loading does not lead to failure. It is further established that the higher the cyclic stress the shorter the life. A second order regression model is developed to predict the fatigue life using response surface methodology and central composite design. Based on cyclic deformation and stress/life (S/N) fatigue behavior, it is found that turn-assisted deep cold rolling can be quite effective in retarding the initiation and initial propagation of fatigue cracks in AISI 4140 steel. © Research India Publications.