Faculty Publications
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Item Effect of reversion heat treatment on the mechanical properties of thermally embrittled UNS S32760 duplex stainless steel(Trans Tech Publications Ltd ttp@transtec.ch, 2015) Natesh, M.; Shamanth, V.; Ravishankar, K.S.Duplex Stainless Steels contain very high chromium contents (19-30% by weight) and exhibit excellent corrosion resistance and extremely good mechanical properties. Embrittlement of duplex stainless steels due to precipitation of αʹ upon prolonged exposure in the temperature range of 280°C to 500°C has been a serious limiting factor for its long term usage in the nuclear industry, where the operating temperatures of cooling pipes is around 300°C. In this investigation, the effect of reversion heat treatment on the mechanical properties of a thermally embrittled duplex stainless steel has been studied. The specimens were solutionized, aged and then reversion treated for varying periods. The aged specimens showed significant increase in tensile strength and decrease in ductility in comparison to the ones in solutionized condition. The specimens which were reversion treated showed marginal decrease in tensile strength and significant increase in ductility after 5 minutes of holding time. As the holding time increased, the tensile strength rapidly decreased and ductility increased initially up to 30 minutes of reversion, after which there was no significant change in strength and ductility. © (2015) Trans Tech Publications, Switzerland.Item Impact On Leaching Behaviour Of Toxic Metals In Ferrochrome Ash With Varying Ph Levels(American Institute of Physics Inc., 2022) Krishnamurthy, M.P.; Devatha, C.P.In the current investigation, leaching behaviour of cobalt (Co), copper (Cu), iron (Fe), zinc (Zn), calcium (Ca), arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), nickel (Ni), lead (Pb) and selenium (Se) from fresh and aged Ferrochrome Ash (FCA) samples were studied under various pH conditions (3-11). Results reveal that most of the elements follow oxyanionic leaching pattern where increase in pH increases the effluent concentration of elements. Leached As, Pb, Hg, Ni and Fe reached peak concentration at alkaline phases. Cd, Cr and Zn followed cationic leaching pattern where increase in pH decreases the concentration. Any specified pattern of leaching is not followed by Ca, Se, Co and Cu. Results of leaching test reveal that the high concentration of chromium leaching was found to be 156.18 and 155 mg/L, concentration of arsenic 13.46 and 12.89 mg/L, concentration of mercury 10.23 and 10.4 mg/L and lead concentration of 6.58 and 6.72 mg/L for fresh and aged FCA ashes respectively. Hence Cr, As, Hg and Pb are identified as significant hazardous pollutants and must not be discharged without being solidified/stabilized. Leached element concentration was not affected significantly by aging of the FCA. © 2022 American Institute of Physics Inc.. All rights reserved.Item Properties of cellulose fibres and waste plastic modified porous friction course mixes(2010) Suresha, S.N.; George, V.; Ravi Shankar, A.U.This paper summarises the laboratory investigation on porous friction course mixes that were modified with cellulose fibres and waste plastics. Porous friction course mixes of three different aggregate gradations were tested for predetermined binder content. The influence of each modifier on the volumetric properties, permeability, aged abrasion loss, and moisture susceptibility of porous friction course mixes were evaluated. In order to determine the significance level of effect of modifiers on the above properties, the tests for analysis of variance (ANOVA) and Tukey's multiple mean comparisons were performed. Results of statistical analyses indicate that the gradations are major source of variations in all response properties. However, modifiers too appreciably contributed in reducing the moisture-induced damages. The findings suggest that shredded waste plastics are potentially useful as modifiers to porous friction course mixes.Item Electrochemical and Exfoliation Corrosion Behavior of Reversion-Treated High-Strength Aluminum Alloy(Springer, 2020) Nandana, M.S.; Bhat, K.U.; Manjunatha, C.M.; Arya, S.B.The present study aims to understand the microstructural modification affecting the electrochemical and exfoliation corrosion (EXCO) characteristics of aluminum alloy 7010. The alloy was aged for two different tempers, namely peak aging (T6) and retrogression and re-aging (RRA). The standard electrochemical polarization tests and EXCO tests were performed on the treated alloys. The microstructure of the alloy observed under a scanning transmission electron microscope revealed the presence of continuous grain boundary precipitates in T6 alloy. These precipitates were formed discontinuously after RRA treatment. The RRA alloy microstructure resulted in a shift toward positive potential. The exfoliation corrosion depth was reduced to 60–70 ?m after RRA treatment, which was measured to be about 250 ?m in T6 condition. The resistance toward the exfoliation corrosion was found to be influenced by the enriched Cu content of precipitates on grain boundary after reversion treatment. The results confirm that the RRA-tempered alloy improves both electrochemical corrosion and EXCO resistance. © 2020, The Indian Institute of Metals - IIM.