Showing papers by "Steel Authority of India published in 2000"

Influence of nonmetallic inclusion characteristics on the mechanical properties of rail steel

Abstract: An extensive investigation has been carried out on six commercial heats of pearlitic rail steel to study the influence of nonmetallic inclusion characteristics on the tensile, fatigue, and fracture toughness properties. The steels investigated were made through the basic oxygen furnace (BOF)-continuous casting route and rolled in the rail and structural mill into 90 kg/mm2 ultimate tensile strength (UTS) grade rails. While tensile properties (yield strength [YS], UTS, and elongation) of the rail steels investigated were found to be insensitive to inclusion type and volume fraction at their present level (0.23 to 0.45%), the fracture toughness and high-cycle fatigue properties were found to be inclusion sensitive. The fracture toughness values of the steels were found to range between 42.33 and 49.88 MPa √m; higher values, in general, were obtained in heats exhibiting lower volume fractions (0.15 to 0.19%) of sulfide inclusions. The high-cycle fatigue limit, i.e., stress corresponding to 107 cycles, was found to be higher in cleaner steels, particularly in those with lower volume fractions of oxide inclusions. This phenomenon was corroborated by scanning electron microscopy (SEM) observations of fracture surfaces, where oxide inclusions in particular were found to be instrumental in crack initiation. Although fatigue life did not show any direct correlation with the volume fraction of sulfides, elongated MnS inclusions were sometimes observed at crack initiation sites of fatigue-tested specimens.

Cold bonded ore–coal composite pellets for sponge ironmaking Part 1 Laboratory scale development

Abstract: There is a need for the development of efficient industrial processes to use iron ore fines of high grade. Attention is particularly drawn to rotary kiln sponge ironmaking technology using lump iron ore, where productivity is low and energy consumption high compared with gas based processes. Fundamental studies carried out elsewhere indicate that the reduction of lump iron is accelerated if a limited amount of carbonaceous material is incorporated in the agglomerate of iron ore fines. Based on these considerations, cold bonded ore–coal composite pellets have been developed for sponge ironmaking in a rotary kiln. These composite pellets were tested in the laboratory and found to reduce very quickly, compared with lump iron ore. Composite pellets were also tested in an 8 t/day rotary kiln sponge iron plant giving enhanced productivity and lower coal consumption, and these results will be presented in Part 2 of this paper (next issue).

Dry cleaning process and system using jet agitation

Abstract: A dry-cleaning process for cleaning articles disposed in a cleaning chamber having jet inflow ports, using carbon dioxide (CO2) from first and second storage tanks, the process including the steps of compressing gaseous CO2 into the first storage tank to cause a positive pressure differential between the first storage tank and the cleaning chamber, filling the cleaning chamber with liquid carbon dioxide by enabling CO2 flow from the first storage tank to the cleaning chamber in response to the positive pressure differential, alternately compressing gaseous CO2 into the first or second storage tanks to cause a pressure differential between the first and second storage tanks, and flowing liquid CO2 between the first and second storage tanks, via the jet ports and through the cleaning chamber, in response to the pressure differential between the first and second storage tanks, to provide jet agitation in the cleaning chamber and a periodically continuous flow of liquid CO2 through the cleaning chamber.

Dry cleaning process using rotating basket agitation

Abstract: A dry cleaning process and system for cleaning articles disposed in a cleaning chamber having a rotatable member therein, using carbon dioxide (CO2) from a storage tank. The process includes causing a pressure differential between the storage tank and the cleaning chamber, filling the cleaning chamber with a predetermined amount of liquid CO2 enabling flow of liquid CO2 from the storage tank to the cleaning chamber in response to the pressure differential, and rotating the rotatable member.

Strength differential effect in four commercial steels

Abstract: The difference between compressive and tensile flow stress of a material at a given strain termed as strength differential (S-D) effect, has been evaluated in case of four commercial steels via a series of heat treated conditions. The results have unequivocally established that the magnitude of S-D was maximum in the as quenched condition and tempering of the quenched structure led to a decrease in S-D. Spheroidised and/or annealed structures exhibited the lowest value of S-D. A linear relationship of S-D value with hardness and mean stress for each case has been established. Attempts have been made to explain the observed S-D effect in terms of models based on atomic mechanism and of continuum mechanics.

Dry cleaning method and apparatus

Abstract: A dry cleaning system is disclosed which utilizes liquid carbon dioxide as the cleaning medium. Two storage tanks are employed in conjunction with a cleaning vessel. One of the storage tanks is employed for pressure equalization with the cleaning vessel, while the other storage tank is employed for bulk solvent transfer to and from the cleaning vessel. The temperature drop associated with pressure equalization is limited to residual liquid solvent in the pressure equalization tank. At the completion of substrate agitation in the cleaning vessel, liquid solvent is transferred back into the bulk transfer tank, while gaseous solvent is extracted into the pressure equalization tank. The temperature of the cleaning vessel and substrates drops during vapor recovery, while the temperature in the recovered vapor is elevated. The return line from the cleaning vessel is routed back into the cleaning vessel where it forms a heat exchange coil. To raise the temperature of the residual solvent in the pressure equalization tank, the recovered gas is introduced through the residual solvent through a sparging tube.

Closure system for a pressure vessel

Abstract: A closure system (10) that provides a lubricated lock pressure vessel (16) is provided. The closure system comprises a clamp ring (12), a hinged door assembly (20), a lock ring (30). The configuration of this system removes lubricants from the region immediately adjacent a pressure vessel entrance to be sealed by the door assembly (20). A method of closing a port in a pressure vessel is also provided.

Evaluating translation quality as input to product development

Abstract: In this paper we present a corpus-based method to evaluate the translation quality of machine translation (MT) systems We start with a shallow analysis of a large corpus and gradually focus the attention on the translation problems The method constitutes an efficient way to identify the most important grammatical and lexical weaknesses of an MT system and to guide development towards improved translation quality The evaluation described in the paper was carried out as a cooperation between an MT technology developer, Sail Labs, and the Computational Linguistics group at the University of Zurich 1 Different types of evaluation for different purposes Sail Labs does various types of translation quality (TQ) evaluations (absolute, comparative, text and sentence-based) and uses different methods (glass-box, black-box evaluations, preand postrelease, using linguistic test suites and real text corpora) Most of the evaluations are from a developer's rather than a user’s point of view Please note that these evaluations were carried out with earlier product versions and the results were used in the development of Sail Labs' current MT technology For this reason, the concrete results included in this paper (statistics and phenomena) do not reflect the current status of Sail Labs' technology Before designing an evaluation method it is crucial to answer the following questions (King, 1997): • What is the purpose of the evaluation? • What exactly is being evaluated? In this paper we focus on a TQ evaluation to answer the question: In which linguistic areas does the evaluated MT system have the most problems? Thus, the purpose of our evaluation is to identify the most costly grammatical and lexical weaknesses so that by concentrating development on these areas, we can most effectively improve the TQ of our systems We did not want to evaluate the overall TQ of our systems, but rather the problems encountered by the worst translations 2 Our Evaluation method ’Survival of the Weakest’ We chose a corpus-based approach as we wanted to measure the performance of the MT system with minimal user involvement (eg, no prior adaptation of bad texts nor lexical coding of unknown words) This means that we checked the ‘performance’ rather than the ‘competence’ of the system (Falkedahl, 1998) We were not merely interested in determining which linguistic problems the system could handle and to which degree, but rather in which areas the system encounters the most severe problems when translating real texts To achieve a realistic distribution of linguistic phenomena, it is best to use a collection of test sentences covering various linguistic phenomena proportional to their frequency of occurrence in corpus texts However, this is very difficult if not impossible to obtain Constructed test suites for linguistic phenomena for which the real occurrence frequency is unknown would also be of little use to us For these reasons, we selected texts from the Internet and from a corpus CD and considered all phenomena occurring in the test corpus To this end, the corpus must be big enough to yield representative frequencies of linguistic phenomena Another advantage of real texts is that they also contain interactions between various linguistic phenomena, which is another important aspect in evaluating the performance of a system The evaluation method described here adopts, on the whole, a black-box approach The advantage is that the evaluation can be outsourced to an institution not involved with the system development This ensures a more objective evaluation After the final step of the black-box evaluation, the external evaluators from the University of Zurich passed the results to Sail Labs system developers who carried out the more time-consuming glass-box evaluation using standard methods (eg, by isolating the suspected phenomenon, tracing the grammar rules etc) In the black-box evaluation we applied a 4-step filtering mechanism, where each step involved narrowing down the set of sentences for the next step according to certain criteria This allowed us to start the evaluation with an extensive data set while continually reducing the data set for the more costly subsequent steps Each metric and its rating scale was defined in written form, where possible also with reference to quantitative assignment criteria (eg, the sentence is bad if more than half is not understandable) From our experience with other evaluation projects and as reported by Sparck-Jones and Galliers (1995), it is crucial to define the evaluation criteria and the values for the text and sentence ratings in as much detail as possible Among the evaluators, crosschecking and regular discussions helped to ensure that the metrics were applied consistently and subjectivity of ratings was kept to a minimum The final result of the evaluation is a list of grammatical and lexical errors with their respective frequencies within the set of worst translations This list documents the causes of the most frequent and severe translation problems with the corpus of real texts 21 Selection of test material For each language direction, we selected between 100 and 140 texts totaling approximately 5500 to 6000 sentences (translation units), mainly from the Internet, some from the ACL/ECI Multilingual Corpus CD1 We chose texts from various subject areas but with little specialised terminology, a) to ensure a good general understanding of the topics by the evaluators, and b) because we develop general-purpose MT technology The texts were short in order to get a broad variety for a given corpus size and contained sentences of varying linguistic style (simple and complex, short and long sentences, listings and other non-sentence structures) Texts were taken from different domains to suit the purposes of the particular evaluation We used general texts as well as texts from data processing, car industry, economics, medicine, biology, geography & geology, recreation & sports, linguistics and art & literature Where available, the texts were translated using the systems‘ relevant terminology lexica In order to capture different linguistic styles pertinent to particular domains we selected texts that served various functions (newspaper, manual, internet, dialog) Due to the fact that we used the texts as we found them and no pre-evaluation changes were made, we decided to exclude texts with severe and multiple spelling errors or slang as we were not interested in evaluating the robustness of the MT system when facing bad input, but rather its performance with relatively wellformed texts 22 Step 1: Evaluate TL texts after translation with the MT system After translation with our MT system, the TL texts were evaluated to identify bad translations The SL sentences were not taken into consideration in this step as we wanted an evaluation of the generated TL as a standalone text The texts were evaluated according to the following three parameters: • understandability (the amount of information that is understood by the reader) • grammaticality (syntactically ill-formed sentences and incorrect morphology) • lexical correctness (number of unknown, ie untranslated words and suitability of chosen words in the given context, not with regard to the SL sentence) These three parameters were chosen to capture the various purposes a machine translation may serve (information translation or input for postediting) Each criterion was rated on a 3-point value scale: 1 Bad 2 Neither bad nor good 3 Good The rating for the three parameters was done paragraph-wise to ensure each paragraph contributed equally to the overall score The average was then computed for the whole text and this introduced decimal scores Each text was evaluated by three persons to reduce subjectivity All texts evaluated as generally not good 1 TL = target language; SL = source language (average point value below 2) progressed to evaluation step 2 The results were documented extensively including valuable additional information on the overall quality of the translated texts in various subject areas We documented the grades for the 3 criteria for each text and computed the average across subject areas Presuming that even texts that are translated well will contain their share of badly translated sentences, by excluding these texts, we are decreasing our set of badly translated sentences for subsequent steps For more accurate data on the frequency of problematic phenomenon, we could have skipped this step and evaluated all sentences immediately However we designed this step to exclude understandable texts with many well translated sentences in order to maximise the relevance of problems contained in the remaining sentences This also has the advantage of excluding texts from certain genres that are generally translated well 23 Step 2: Evaluate individual sentences In step 2, the goal was to identify within the ‘bad‘ texts those sentences that are translated the worst This time, the SL sentences were taken into account for the assessment of the TL sentences to enable a more informed evaluation This step was carried out for approx 3500 – 4000 translation units per language direction We used two metrics which were rated on a 10 pt scale • Preservation of meaning: Is the meaning of the TL sentence the same as the meaning of the SL sentence? 7 – 10 points (Good): meaning of SL and TL sentence is about the same Almost no post-editing with respect to meaning is necessary Example: SL: C’est sur le terrain social que le changement est le

Microstructural features of prematurely failed hot-strip mill work rolls: Some studies in spalling propensity

Abstract: Work rolls made of indefinite chill double-poured (ICDP) iron are commonly used in the finishing trains of hot-strip mills (HSMs). In actual service, spalling, apart from other surface degeneration modes, constitutes a major mechanism of premature roll failures. Although spalling can be a culmination of roll material quality and/or mill abuse, the microstructure of a broken roll can often unveil intrinsic inadequacies in roll material quality that possibly accentuate failure. This is particularly relevant in circumstances when rolls, despite operation under similar mill environment, exhibit variations in roll life. The paper provides an insight into the microstructural characteristics of spalled ICDP HSM work rolls, which underwent failure under similar mill operating environment in an integrated steel plant under the Steel Authority of India Limited. Microstructural features influencing ICDP roll quality, viz. characteristics of graphite, carbides, martensite, etc., have been extensively studied through optical microscopy, quantitative image analysis (QIA), and electron-probe microanalysis (EPMA). These are discussed in the context of spalling propensity and roll life.

Multi-output mode charger

Abstract: A multi-mode output charger is to support different kinds of batteries for the mobile telecommunication facility It comprises a charger and a charge unit Users can choose different charging voltages and charging currents with a voltage and current regulating switch of the charger Therefore, the charger can support different voltage and current combinations for batteries And the charge unit has several kinds of charge connecting set for different brand batteries Also, the charge unit can extend to engage with different mode charge connecting set for enlarging its supporting range

Improvement in internal quality of boiler plates at Bhilai Steel Plant

Abstract: Bhilai Steel Plant produces plates of boiler, high tensile and other special quality steels via the basic oxygen furnace–vacuum arc degassing–continuous casting route. These plates need to be ultrasonically sound. However, rejection of plates on account of internal defects was high. Metallurgical investigations of defective plates showed the presence of a martensitic zone associated with cracks around the centreline. The martensitic transformation is favoured by segregation of carbon and other elements. The published literature confirms that, even at a normal cooling rate, martensite formation is possible when the concentration of carbon at the central region is high. Bhilai Steel Plant slab casters have certain inherent deficiencies such as a high roll pitch and low machine rigidity, which lead to strand bulging. High strand bulging causes centreline segregation. Segregation during solidification can be controlled by various techniques including low superheat casting, electromagnetic stirring, me...

Knowledge management system: a case study of RDCIS laboratories

Abstract: Knowledge Management System, with its database consisting of details of equipment capability, test methods, references and expertise of individuals is introduced in RDCIS laboratories through existing wide spread LAN on windows NT platform. Being a R&D organisation, both codification and personalisation strategies were adopted carefully to reuse and share the knowledge efficiently. This involves capturing of inherent knowledge and storing it in a web based hyperlinked information system so that it can be retrieved whenever and wherever needed. A two layer K M platform, based on Distributed interNetApplications of Microsoft has been designed and implemented successfully for this purpose. Significant improvement has been noticed in effective utilisation of equipment potential through systematic approach of knowledge sharing beside continuous enrichment of data bank.

System for the continuous Online recognition of slippage in mill trains includes a device for measuring the voltage, current strength and speed of the motor

Abstract: System for the continuous Online recognition of slippage in mill trains comprises a device for measuring the voltage, current strength and speed of the motor; devices for determining rolling conditions and foot lever position; a receiver for the detected signals via the rolling machine; and analyzer for the data/signals of the motor and the rolling conditions; a device for producing alarm conditions when the slippage exceeds the boundary value; and a regulator for the motor voltage.

Reconstructing Conversational Games in an Obligation-Driven Dialogue Model

Abstract: Departing from a dialogue model that uses discourse obligations as basic expressive means we will propose a set of inference rules that assign intentional structures to sequences of dialogue moves. We then can demonstrate that from our point of view conversational games can be seen as macrostructures which are decomposable into smaller functional units where the coherence between the latter is explained in terms of obligations.