Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
Browse
3 results
Search Results
Item Investigation of Microstructure and Mechanical Properties of ECAP-Processed AM Series Magnesium Alloy(Springer New York LLC barbara.b.bertram@gsk.com, 2016) Gopi, K.R.; Shivananda Nayaka, H.S.; Sahu, S.Magnesium alloy Mg-Al-Mn (AM70) was processed by equal channel angular pressing (ECAP) at 275 °C for up to 4 passes in order to produce ultrafine-grained microstructure and improve its mechanical properties. ECAP-processed samples were characterized for microstructural analysis using optical microscopy, scanning electron microscopy, and transmission electron microscopy. Microstructural analysis showed that, with an increase in the number of ECAP passes, grains refined and grain size reduced from an average of 45 to 1 µm. Electron backscatter diffraction analysis showed the transition from low angle grain boundaries to high angle grain boundaries in ECAP 4 pass sample as compared to as-cast sample. The strength and hardness values an showed increasing trend for the initial 2 passes of ECAP processing and then started decreasing with further increase in the number of ECAP passes, even though the grain size continued to decrease in all the successive ECAP passes. However, the strength and hardness values still remained quite high when compared to the initial condition. This behavior was found to be correlated with texture modification in the material as a result of ECAP processing. © 2016, ASM International.Item Investigation of microstructure and mechanical properties of the Cu-3% Ti alloy processed by multiaxial cryo-forging(Cambridge University Press, 2018) Ramesh, S.; Shivananda Nayaka, H.; Gopi, K.R.; Sahu, S.; Kuruveri, U.B.A Cu-3%Ti (wt%) alloy was processed by multiaxial forging (MAF) at cryogenic temperature up to 3 cycles, imposing a total strain of 1.6. Microstructure and mechanical properties of the unprocessed and cryo-forged samples were analyzed. X-ray diffraction results showed deviation in peak broadening and peak intensity of the cryo-forged samples in comparison to that of unprocessed, which are due to texture modification caused by grain refinement during the MAF process. Microstructural analysis showed reduction in grain size from 80 m in the as-received condition to 250 nm after 3 cycles. Electron backscatter diffraction results indicated the transformation of high angle grain boundaries to low angle grain boundaries in all 3 cycles when compared to the as-received condition. Reduction in ductility was observed after 1 cycle, but with an increase in the number of cycles, both strength and ductility increased. After 3 cycles, ultimate tensile strength and hardness reached 1126 MPa and 427 Hv as compared to 528 MPa and 224 Hv for the as-received condition. Fractography analysis showed decrement in dimple size after 1 cycle, in comparison to that of the as-received condition. However, it kept on increasing for higher number of cycles. © © Materials Research Society 2018.Item Enhancing wear resistance of AZ61 alloy through friction stir processing: experimental study and prediction model(Institute of Physics, 2024) Anne, G.; Ramesh, S.; Sharma, P.; Maruthi Prashanth, B.H.; Aditya Kudva, S.; Kumar, P.; Sahu, S.; Bhat, N.In this study, friction stir processing (FSP) is proposed for the treatment of AZ61 alloy, and an artificial neural network is built to predict and compare the experimental wear results. The effects of different processing parameters, including spindle speed (800-1200 rpm), traveling speed (5-15 mm min−1), and depth of press (0.8-1.2 mm) on the microstructural evolution, mechanical properties, and wear behavior are investigated. Microstructural analysis reveals a grain size of 14 ± 2 μm for the FSP1 sample, with observed shifting of x-ray diffraction (XRD) peaks, indicative of texture development. Increasing spindle and traveling speeds increase the surface roughness, as observed by average roughness (Ra) values of 68.4 nm for a rotational speed of 800 rpm, traveling speed of 5 mm min−1, and shoulder depth of 0.8 mm (FSP1) and 116.3 nm for rotational speed of 1200 rpm, traveling speed of 15 mm min−1, and shoulder depth of 1 mm (FSP9). Microhardness values increase to 113.36 Hv for FSP1 and 79. 51 Hv for FSP9 compared to 65.92 Hv for the base material (BM) sample. The decrement in hardness from FSP1 to FSP9 can be attributed to increased heat input, resulting in coarse microstructure. Wear results show that FSP1 exhibits the lowest weight loss (0.003 g) and coefficient of friction (COF) (0.28) compared to other FSP conditions and BM samples (weight loss of 0.022 g and COF of 0.68). This work demonstrates the efficacy of friction stir processing in enhancing the wear resistance of magnesium alloys. © 2024 The Author(s). Published by IOP Publishing Ltd.