Articles / Abstracts

Different Aspects of Electron Microscopy
Deepak Rajput and S.K. Tiwary
Essar Steel Limited, Hazira, Gujarat, India (2005)
Note: This paper was presented in a national workshop on electron microscopy in SVNIT, Surat, India.

Summary:  The resolving power of any microscope depends upon the wavelength of the source of illumination, and the smaller the wavelength, the higher is its resolving power. Light waves have wavelengths between 4000 and 7000 � that limit the resolution of conventional light microscopes to 0.2 micrometer and magnification to the order of 1000 times. The limitation of light microscope in terms of resolution and magnification leads to the need for better source of illumination than monochromatic beam of light. It is well known a fact that electrons has wave-like nature and their wavelength is given by de Broglie�s equation. A beam of highly accelerated electrons can be used as a source of illumination in microscopes to achieve very high level of resolutions and magnifications, and such microscopes are called as electron microscopes. In conventional electron microscopes, electrons are generated as a result of thermionic emission by applying high voltage to a thin hairpin filament (usually tungsten or lanthanum hexaboride). The generated beam of electrons is unstable in nature and thus requires a high level of vacuum for its stability. The attainment of vacuum for successful journey of electron beam from the electron gun to the specimen surface is done with the help of various kinds of pumps and is discussed in this paper. When a beam of high-energy electrons interacts with the specimen under study, various different kinds of signals are generated as a result of elastic and inelastic scattering. The kinds of signals generated and the information they provide are discussed at length in this paper. Different features of electron microscopy are discussed in this paper to provide better understanding of the subject as a whole, but an emphasis is made more on scanning electron microscopy. Typical applications of electron microscopy are also discussed in brief in this paper.

Development of Interstitial Free Steel (IF) in Galvanized Condition at Essar Steel
Aviral Chaturvedi, Deepak Rajput, Bobby Pujara, Rajesh Kaul
Essar Steel Limited, Hazira, Gujarat, India (2005)
Note: This paper was selected for oral presentation in NMD-ATM 2005, but was not presented due to miscommunication.

Summary:  Low carbon (~0.02%) Al-killed steels are the conventional grade for producing cold rolled extra deep drawing (EDD) sheet. However they possess low drawability as compared with interstitial free steels. Their typical r-bar values are 1.6 as against ~2.0 in interstitial free steel. Till about two years back, the requirement of interstitial free steel grade for stringent drawing application in India was met through import only. The paper describes the development and production of interstitial free steels in galvanized condition.

Keeping that purpose at its core, Essar Steel Limited has developed IF steel in galvanized condition through their Galvanizing Line-1.Heats were made with EAF-VD-slab casting route. Special precautions were taken during steel making and slab casting to get the low amount of interstitials in the steel. Laboratory studies were conducted to select the process parameters for hot rolling, cold rolling and galvanizing. The slab thickness was 220mm. The slabs were hot rolled to 3.2 and 3.5 mm thicknesses. The HR coils were pickled and were given ~80% cold reduction prior to galvanizing. The process parameters in the galvanizing like RTF, Soaking and bath temperatures were selected to get the desired properties.

The properties achieved after galvanizing were YS � 130 to 140 MPa, UTS � 290 to 320 MPa and % Elongation � 42 to 47. The coating thickness was 120 GSM. These properties met the customer�s requirement as per standard EN10142 DX 57D.

General Study of P/M Processed Al � Cu Alloys and Their Rolling Characteristics
Deepak Rajput, Sandeep Bhattacharjee, Kushal K. Nandedkar, T. Srinivasa Rao
National Institute of Technology, Trichy, India (2004, unpublished, Bachelor's thesis)

Summary:  The basic purpose of this project was to study rolling characteristics of few aluminum-copper alloys manufactured through powder metallurgy route. The samples were processed in the following manner: The powders (aluminum and copper) were blended for 6 hours and then compacted using single-end die compaction. Aluminum-Copper alloys produced were: Al - 0.5% Cu, Al � 1.5% Cu, Al � 2.5% Cu and Al � 4% Cu. A double coating of aluminum was applied on the compacted samples that were then dried for 8 hours. The samples were then sintered at a temperature of 540�C. The samples were then cold rolled in a two high rolling mill. The density of each sample was determined using Archimedes� principle after 5, 8 and 12 passes. The hardness was measured after the same number of passes. Graphs were plotted for density & hardness vs. number of passes and hardness vs. % reduction in thickness. Rolling characteristics of these alloys were studied with the obtained results.

Effect of Lubricants on Green Density Behavior of Warm Compacted 904L Stainless Steel
Deepak Rajput, Sandeep Bhattacharjee, S. Kumaran, T. Srinivasa Rao
National Institute of Technology, Trichy, India (2003, unpublished)

Summary:  The primary objective was to study the variation in green density of compacts formed after compaction using different admixed lubricants at different temperatures. Lubricants used were lithium stearate, zinc stearate and 50% Li stearate-50% Zn stearate mixture. Mechanical alloying of powders was carried out in a planetary type ball mill and then warm compaction was done in a die with a heater mounted on a universal testing machine. Density and Resistivity were calculated after compaction and graphs of Density vs. Temperature and Resistivity vs. Temperature were plotted. A comparative study of warm compaction and cold compaction was done with the obtained results.

Wear Study of Iron Aluminide Intermetallic Compound
Deepak Rajput, Sandeep Bhattacharjee, Garima Sharma
Bhabha Atomic Research Center, Mumbai, India (2002, unpublished)

Summary:  The project was focused on the study of wear resistance of iron aluminides based on DO3 structure. Wear tests were performed on the micro-friction machine offering friction evaluation and wear testing facilities having ball-on-plate set up. The sample plates used were iron aluminide of composition Fe-28Al-3Cr. The wear tests were performed at different speed and load condition to study their effect on wear rates. The micromechanisms responsible for wear were studied in detail by Scanning Electron Microscope. Two mechanisms were found to exist: Microploughing and Microcutting.