Institution
Defence Metallurgical Research Laboratory
Facility•Hyderabad, India•
About: Defence Metallurgical Research Laboratory is a facility organization based out in Hyderabad, India. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 1208 authors who have published 2662 publications receiving 51663 citations.
Topics: Microstructure, Alloy, Ultimate tensile strength, Creep, Coercivity
Papers published on a yearly basis
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TL;DR: In this paper, the effect of welding consumables on high cycle fatigue properties of high strength, quenched and tempered (Q&T) steel joints was investigated using three different consumables namely (i) austenitic stainless steel, (ii) low hydrogen ferritic steel, and (iii) high nickel steel have been used to fabricate the joints by shielded metal arc welding process.
Abstract: Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to their high strength-to-weight ratio and high hardness. These steels are prone to hydrogen-induced cracking in the heat affected zone (HAZ) after welding. The use of austenitic stainless steel consumables to weld the above steel was the only remedy because of higher solubility for hydrogen in austenitic phase. Recent studies proved that high nickel steel and low hydrogen ferritic steel consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. In this investigation an attempt has been made to study the effect of welding consumables on high cycle fatigue properties of high strength, Q&T steel joints. Three different consumables namely (i) austenitic stainless steel, (ii) low hydrogen ferritic steel, and (iii) high nickel steel have been used to fabricate the joints by shielded metal arc (SMAW) welding process. The joints fabricated using low hydrogen ferritic steel electrodes showed superior fatigue properties than other joints.
18 citations
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TL;DR: In this article, the authors investigated the effect of Al content on the power law creep behavior of titanium aluminide alloys in terms of the activation energies and stress exponents.
Abstract: Small increases in the Al content of Ti{sub 3}Al-Nb alloys are known to improve creep resistance at the expense of the room temperature ductility. Though considerable work has been done on the creep behavior of titanium aluminide alloys, a systematic investigation involving the role of Al on the creep of aluminides is lacking. In the present study the authors have therefore carried out a complete investigation on stress and temperature effects on two alloys with differing Al contents, Ti-24Al-15Nb and Ti-26Al-15Nb (nominal composition in at%) in order to understand the effect of Al in terms of power law creep behavior. The following conclusions are made: (1) A strong Al effect on the creep resistance of O phase alloys in the Ti-Al-Nb systems has been confirmed, through a study of stress and temperature effects on the creep behavior of the Ti-24Al-15Nb and the Ti-26Al-15Nb compositions. (2) It has been shown, however, that the small differences in Al do not affect either the activation energies for creep ({approximately}370 kJ/mole) or the creep mechanism (climb controlled creep with a stress exponent of 4). The activation energies and stress exponents are similar to that observed in single phase O alloys. (3) It is suggestedmore » that Al influences creep strength through an intrinsic effect on the pre-exponential term AD{sub o} in the power law creep equation. It is possible that this effect is related to a higher ordering energy of the O phase with increasing Al content.« less
18 citations
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15 Jan 2010-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, a series of hypereutectic alloyed gray iron compositions with carbon equivalent from 4.37 to 5.14 was studied to understand the influence of microstructure on its mechanical and wear properties.
Abstract: The austempering behavior of a series of hypereutectic alloyed gray iron compositions with carbon equivalent from 4.37 to 5.14 was studied to understand the influence of microstructure on its mechanical and wear properties. The alloying elements in the alloys included Ni, Mo, Cr and inoculation by micro-constitution of Ti, Nb and Ce. The alloys were austempered at 360 °C and upper bainitic type feathery ferrite was observed in the matrix. While the graphite content determined by optical metallography varied between 16 and 24 vol%. The volume of austenite determined by XRD analysis showed values between 20 and 26%. The ferrite lath size was determined using XRD peak broadening. The tensile property varying between 188 and 270 MPa, showed no significant variation with volume percentage of carbon or austenite in the ausferrite. However the wear rate varying between 0.5 and 2.6 × 10−7 g/Nm, showed a decreasing trend with graphite content attributed to the higher lubricating effect of released carbon during sliding wear. The specific wear rate of hypereutectic alloys, increased with increasing ferrite lath size due to enhanced softer ferrite phase on the sliding surface. The wear rate was found to increase with volume of austenite, austenite carbon content and austenite lattice parameter, which is attributed to increased stability of austenite against strain induced martensite formation and the increased formation of bainitic carbides in the second stage tempering. The various technical aspects in correlating the microstructure with the mechanical and wear properties of hypereutectic austempered gray iron are described.
18 citations
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TL;DR: In this paper, the influence of welding consumables and welding processes on metallurgical characteristics of armour grade Q&T steel joints was studied by various metallogical characterization procedures, and the results showed that the joints fabricated by using low hydrogen ferritic steel (LHF) consumables offered lower degree of HAZ softening and there was no evidence of hydrogen induced cracking in the joint fabricated using LHF consumables.
18 citations
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TL;DR: In this article, a stress compensated MEMS magnetic actuator based on Fe65Co35 thin films was designed for 25 kHz mechanical resonance frequency using a finite element method, and the experimental resonance frequency measured using laser Doppler vibrometer was found to be around 25.275 kHz which is close to simulated resonance frequency.
Abstract: We have developed a stress compensated MEMS magnetic actuators based on Fe65Co35 thin films. The magnetic actuator was designed for ˜ 25 kHz mechanical resonance frequency using a finite element method. The cantilever layer stack consists of Si/SiO2/Fe65Co35 multilayers where silicon dioxide (SiO2) layer stress is compressive and Fe65Co35 layers is tensile in nature. The bilayer combination nullifies the film stress which result to a stress compensated undeformed released micro-actuator. Further, cantilevers are mounted on a piezo-disk and the experimental resonance frequency measured using laser Doppler vibrometer was found to be around 25.275 kHz which is close to simulated resonance frequency. Using cantilever deflection method, the magnetostriction coefficient (λ) measured was found to be ˜135 ppm. This study also suggests the possibility to realize variety of stress compensated magnetic MEMS devices based on stress compensation in bilayers. Further, the results also indicate that the compensation mechanism can be applied to magnetic MEMS devices for reliable device fabrication and operation. The developed magnetostrictive micro-actuator has potential applications in magnetic MEMS for low field sensing and actuation applications.
18 citations
Authors
Showing all 1215 results
Name | H-index | Papers | Citations |
---|---|---|---|
Rajiv S. Mishra | 64 | 591 | 22210 |
G. Sundararajan | 46 | 241 | 8402 |
Dipankar Banerjee | 44 | 366 | 9025 |
Satyam Suwas | 43 | 412 | 7655 |
G. Madhusudhan Reddy | 38 | 168 | 4580 |
Animesh Dutta | 38 | 299 | 7014 |
Om Prakash Pandey | 37 | 441 | 6403 |
Shrikant V. Joshi | 34 | 229 | 4119 |
Arumugam Pandurangan | 34 | 183 | 3708 |
Dibyendu Ganguli | 33 | 147 | 3122 |
K. T. Jacob | 33 | 364 | 5026 |
E. S. R. Gopal | 31 | 237 | 4191 |
Rahul Mitra | 31 | 191 | 3698 |
Bhaskar Majumdar | 30 | 160 | 3065 |
Jainagesh A. Sekhar | 29 | 219 | 2524 |