Showing papers by "Steel Authority of India published in 2006"

Epidemiology of malaria transmission in forest and plain ecotype villages in Sundargarh District, Orissa, India

Abstract: A study of the epidemiology of malaria transmission was undertaken in 13 tribal villages located in forest and plain areas of Sundargarh District of Orissa state, India, from January 2001 to December 2003. In forest areas, intense transmission of malaria is attributed to the highly anthropophagic vector Anopheles fluviatilis sibling species S and is complemented by A. culicifacies sibling species C. In plain areas, A. culicifacies sibling species C is responsible for malaria transmission. The entomological inoculation rate in the forest and plain areas was 0.311 and 0.014 infective bites/person/night, respectively, during 2003. Malaria transmission is perennial both in forest and plain areas but is markedly low in the plain area compared with the forest area. Plasmodium falciparum accounted for 85.0% of the total malaria cases during the study period. In forest and plain areas, the number of P. falciparum cases per 1000 population per year was 284.1 and 31.2, respectively, whereas the parasite rate was 14.0% and 1.7%, respectively. In forest areas, clinical malaria occurs more frequently in children aged 0-5 years and declines gradually with increasing age. The study showed that villages in forest and plain areas separated by short geographical distances have distinct epidemiology of malaria transmission.

Effect of rare earth elements on microstructure and oxidation behaviour in TIG weldments of AISI 316L stainless steel

Abstract: The influence of rare earth addition in weld metal, on the microstructure and oxidation behaviour of AISI 316L stainless steel in dry air under isothermal condition at 973 K for 240 h is reported. Rare earth metal (REM) doped weld metal zone exhibits better oxidation resistance during isothermal holding as compared to base metal and undoped weld metal zone of 316L. Presence of both Ce and Nb in weld metal shows superior oxidation resistance than with Ce alone. TIG weld microstructures are presented by optical microscopy. The morphologies of the scales and nature of their adherence to the alloy substrates, and scale spallation have been characterized by SEM and EDAX.

Microstructures and properties of low-alloy fire resistant steel

Abstract: Microstructures and properties of weldable quality low-alloy fire resistant structural steels (YS: 287–415 MPa) and TMT rebar (YS: 624 MPa) have been investigated. The study showed that it is possible to obtain two-thirds of room temperature yield stress at 600°C with 0.20–0.25% Mo and 0.30–0.55% Cr in low carbon hot rolled structural steel. Microalloying the Cr-Mo steel by niobium or vanadium singly or in combination resulted in higher guaranteed elevated temperature yield stress (250–280 MPa). The final rolling temperature should be maintained above austenite recrystallization stop temperature (∼ 900°C) to minimize dislocation hardening. In a quenched and self-tempered 600 MPa class TMT reinforcement bar steel (YS: 624 MPa), low chromium (0.55%) addition produced the requisite yield stress at 600°C. The low-alloy fire resistant steel will have superior thermal conductivity up to 600° C (> 30 W/m.k) compared to more concentrated alloys.

VSC Based HVDC System for Passive Network with Fuzzy Controller

Abstract: For stable operation of a power system reliable control of active & reactive power is necessary Voltage source converter based HVDC system bears the advantages of being able to change the control strategy immediately with respect to the active and reactive power changes In this paper a function based fuzzy control system is proposed for the control of active power, DC voltage at converter station and voltage at inverter station Basically two input one output methodology based fuzzy logic controller has been proposed The basic features of proposed system used in VSC based HVDC systems are: 1) only two rule base system is used2) all controllers are not self correcting At both stations error and change in error have been taken as input to the controller Design of high pass filter with FFT analysis has also been proposed for a better dynamic performance of the function based fuzzy controller Computer simulation using Simulink gives clear result of the performance of the proposed controller

Influence of austempering parameters on the microstructure and tensile properties of a medium carbon–manganese steel

Abstract: Austempering heat treatment practice helps in achieving high strength with good ductility and toughness by evolving a predominantly bainitic microstructure in the steel. Further, austempering practice can be modified to facilitate formation of some amount of ferrite and pearlite along with bainite which in turn enhances the ductility with some lowering of strength in the steel. The actual strength and ductility depends upon the relative amount of ferrite, pearlite and bainite present in the austempered steel. Present study was taken up to understand the influence of austempering parameters like austenitising temperature and cooling rate on the microstructure of an austempered steel with 0.4% carbon and 1.4% manganese. Laboratory simulation studies on conventional austempering showed that a microstructure comprising predominantly bainite with up to 4% ferrite was evolved which imparted a tensile strength of 120 kg/mm 2 and elongation of 4% (at 150 mm gauge length) to the austempered steel. On the other hand, when the steel was subjected to modified austempering practice which included austenitising at different temperatures for a period of 2 min followed by controlled air cooling and quenching in a lead bath at 450 °C, variety of microstructures were obtained. Particularly, when the steel was austenitised at 870–900 °C, a microstructure comprising uniformly distributed fine pearlite and bainite in a matrix of ferrite was formed. This microstructure resulted in tensile strength of 95 kg/mm 2 and elongation of 9% (at 150 mm gauge length). Based on the results achieved in this study, a relationship was established between tensile properties and the volume fraction of ferrite formed during austempering of steel.

Spheroidisation Treatment for Steels

Abstract: The materials used in components are now highly diversified with many applications historically reserved for steels now taken by plastics, composites, and ceramics. There are, of course, many applications for which steels are still the most suitable material. Presently, it is important that the type of steel chosen for a given application and the heat treatment given to it be critically examined to justify its use. This study highlights the selection of steels for spheroidisation treatments and their commercial uses.

The Structure And Properties of a Thermo‐mechanically Processed Low Carbon High Strength Steel

Abstract: Research efforts were given towards development of low carbon high strength steels since recent past. The present study deals with the development of a low carbon high strength steel alloyed with Mn, Ni, Mo, Cu and microalloyed with Ti and Nb. The steel was subjected to three stage controlled rolling operation followed by accelerated cooling. The structure and properties of the steel at various processing conditions were evaluated. Microstructural observation reveals predominantly lath martensite along with twinned martensite structure at all processing conditions. High strength values at higher finish rolling temperatures have been obtained due to fine martensitic structure along with tiny precipitates of microalloying carbide and carbonitride. The strength value increases marginally at lower finishing temperature due to comparatively finer lath size of martensite and increased precipitation density of carbides, carbonitrides along with Cu particles. The variation in impact toughness properties at different finish rolling temperatures is found to be negligible at ambient and subambient temperatures. The formation of stable and large TiN/TiCN particles during casting have impaired the impact toughness values at ambient and at -40 degrees C temperatures.

Influence of Welding Speed on Microstructure and Oxidation Behaviour of Laser Welded Austenitic Stainless Steels

Abstract: Microstructure and high temperature oxidation behaviour of laser weldments of 316L and 316LN steels have been found to influence by the variation in welding speed. Ferrite content and ferrite morphology change for both type 316L and 316LN laser weld with welding speed. Laser weldments consisting mainly of weld metal and base metal region of two austenitic stainless steels (ASS) were oxidized in dry air at 973 K for 240 h. Steel weldment was found to have a higher oxidation rate when joined with lower welding speed of 11.66 mm/s as compared to 25 mm/s speed. On the other hand, 316LN steel weldments have indicated much superior oxidation resistance property under similar condition. Oxidation behaviour of two ASS weldments has been correlated with microstructure and oxide scales formed over the different regions have been characterized by scanning electron microscopy (SEM/EDXA).

Wind sail receptor

Abstract: A wind sail receptor for turning in a wind or flow of water, turning an axle that operates a power generator device that produces a power output for performing work or provides for passing that power output to a storage arrangement. The wind sail receptor preferably includes, from six to ten identical, equally spaced blades between a rear hub and a forward disk, with the rear hub and forward disk connected to an axle that is mounted to a frame through bearings, allowing the wind sail receptor to turn freely when it is pointed into a wind or water flow. Which wind sail receptor blades are formed from two sections of three to five equal spaced blades, and each section is formed from a single flat section of a stiff material, wherefrom radial sections have been removed to form the individual blades that are equal spaced around a hub, and which section hubs are fitted to one another and the blades bent into like curves, and outer blade ends are secured, at equal spaced intervals to a forward disk, forming the wind sail receptor.

Studies on dephosphorisation of steel in induction furnace

Abstract: Steel melters who use recycled steel scrap in small induction furnaces have no control on phosphorus input from scrap. For furnaces of capacity less than 2T, dephosphorisation in external ladle is not possible owing to excessive heat loss. Studies on dephosphorisation were thus carried out in the induction furnace itself using lime based fluxes with and without addition of fluxing agents like CaF 2 and Na 2 O. The fluxes were added directly and also added through injection. The effects of individual components of fluxes on dephosphorisation were estimated. Correlation were developed between dephosphorisation and different expressions of basicity values. An operator can easily use these correlation to predict dephosphorisation levels depending on type of flux used and mode of addition.

The application of seismic-geological integrated interpretation in the eastern depression of the Liaohe oil field

Abstract: It is very important to comprehensively interpret areal seismic data with geological data in a research area. For the structural interpretations in the middle depression of the eastern basin of Liaohe oilfield, we first analyze and study geological phenomena on outcrop pictures collected in the field and establish geological outcrop models. Second, we make fault and structural interpretations based on the structural characteristics of the outcrop pictures. Third, we analyze the migration, accumulation, and formation of oil and gas using characteristics of seismic profiles. By geologic and geophysical comprehensive interpretation, it is inferred that, in the research area, the dominant factor controlling oil and gas accumulation is strike-slip faults. Structural modes and the relationship of the oil and gas in the Huangshatuo and Oulituozi oil fields are also analyzed and investigated.

Investigation into the cracking of inner cover of batch annealing furnace at bokaro steel plant

Abstract: A detailed metallurgical investigation was undertaken to ascertain the cause of the premature cracking of inner covers used in the batch annealing furnaces of Bokaro Steel Plant of the Steel Authority of India Limited (SAIL). It was found that the cracking was a result of the profuse precipitation of chromium carbide. Precipitation of chromium carbide sensitizes the steel to corrosion attack because of denudation of chromium from the matrix. Use of a properly stabilized austenitic stainless steel was recommended for prolonged life of the inner covers.

Electromagnetic sensor for close gap detection Between two contiguous slabs

Abstract: The slabs in the steel plants are rolled for producing thinner gauge plates. When these slabs are charged on the roll table for pre-heating and rolling in the mill for gauge reduction they move very close to each other. The movement of slabs is in a contiguous manner on the roll table virtually touching and pushing each other. Therefore, it becomes very difficult to detect or distinguish the slabs on the roll table before their further processing in the mill. This paper describes the application of electromagnetic principle to detect the gaps between contiguous slabs on the roll table. As no such sensor was readily available therefore it was developed and tested. This sensor shall help in identifying the slabs moving contiguously on the roll table. On identification of the gaps between the slabs the sensor output can be interfaced to any system in the mill which takes care of the material tracking of the processed slabs.