Physical Metallurgy

Physical Metallurgy deals with the relationship between structure and properties of metals and alloy. The process adopted for metal extraction from the ores and subsequent fabrication influences the structure. The properties of interest are mainly those demanded by engineers such as strength, ductility toughness and corrosion resistance. Thus physical metallurgy provides a vital link in making, shaping, treating and using of metals and alloys. Physical metallurgy deals with the nature, structure and physical properties of metals and alloys, together with-the mechan-ism of varying such properties

Failures due to improper hardening of steel components

Components made up of steel are often quenched, so that they become hard due to the formation of martensite. The quenching rates through out the component, however, changes depending on the section size. Wher¬ever the rate of cooling is greater than the critical cooling rate marten¬sitic microstructure is obtained. In a specified standard quenchant the depth of martensitic case being a characteristic of the steel is known as hardenability. Hardenability is characterized by critical diameter (D) or critical plate thickness (L) which corresponds to the formation of 50% martensite -50% pearlite at the centre. This, D1, is dependent on the car¬bon content, austenite grain size and various alloying elements. Pres¬ence of alloying elements lead to increase in hardenability by delaying the ferrite pearlite transformation. However, the differential cooling rates encountered by the component produces stresses leading to distor¬tion and cracking. To reduce these stresses, hardened materials are sub¬jected to tempering to make a balance between hardness and toughness required in service. This also determines the conditions of tempering for a given application. Case studies will be presented to show the effect of the quenching response and the subsequent tempering treatment for a component depending on its specific application requirements

Thermomechanical Processing of Metals and Alloys

For commercial products in any industry, their external shapes are the result of hot deformation i.e. hot rolling. The necessary mechanical properties are deduced from the alloy design and through heat treatment after hot-deforma-tion. Thermomechanical processing (TMP) is a technique designed to improve the mechanical properties of materials by controlling the hot-deformation processes, which origi-nally were designed to produce the required external final shape of the product.The first introduction of TMP for commercial production was controlled rolling of C-Mn steel plates of 40kgf/mm2 grade for ship-building in the 1950s. During the World War II, a number of transport ships, so-called 'Liberty' ships suffered from the occurrence of brittle fractures initiated at welded joints. This inci-dent stimulated the concept of toughness, which is diff-erent from the concept of ductility, and notch toughness became a requirement for ship-building and other structu-ral steel plates. At that time, the concept of ductile-brittle transition temperature through grain refinement was introduced. It was reported that an improvement of about 10-15°C in the 20J transition temperature could be possible through controlled low temperature hot-rolling process

Security-constrained Optimal Rescheduling of Real Power using Hopfield Neural Network

A new method for security-constrained corrective rescheduling of real power using the Hopfield neural network is presented. The proposed method is based on solution of a set of differential equations obtained from transformation of an energy function. Results from this work are compared with the results from a method based on dual linear programming formulation of the optimal corrective rescheduling. The minimum deviations in real power generations and loads at buses are combined to form the objective function for optimization. Inclusion of inequality constraints on active line flow limits and equality constraint on real power generation load balance assures a solution representing a secure system. Transmission losses are also taken into account in the constraint function

CFD Modeling of Globe Valves for Oxygen Application

Components used in high-pressure, high-temperature, flowing oxygen are susceptible to ignition and combustion in presence of restriction or when particles impact these restriction. The valves in any systems are the common flow restrictors, hence, the design and analyses of valves are most critical tasks. The flow of oxygen through valves distinguishes itself by accentuating auto-ignition and consequent flame propagation in metals and non-metals, apart from other usual characteristics present with gases/liquids. The combination of ignition resistance, proper and reliable performance and fabrication economy marks the specification of material and design of valves in oxygen-enriched environment. The analyses have been performed by applying the commercial computational fluid dynamics (CFD) code, FLUENT, to obtain the solution of the two-dimensional turbulent flow field through a globe valve for its different openings in the GOX environment. The flow control valves in high velocity oxygen systems for different openings are simulated for turbulence and eddy dissipation. The influence of pressure, flow rate and opening of the valve on the rise in temperature and eddy dissipation rate is also obtained for compressible flow range. The simulation for turbulence is done by k- and k- turbulence models and the results have been compared

Room temperature multiferroicity in orthorhombic LuFeO3_3

From the measurement of dielectric, ferroelectric, and magnetic properties we observe simultaneous ferroelectric and magnetic transitions around $\sim$600 K in orthorhombic LuFeO$_3$. We also observe suppression of the remanent polarization by $\sim$95\% under a magnetic field of $\sim$15 kOe at room temperature. The extent of suppression of the polarization under magnetic field increases monotonically with the field. These results show that even the orthorhombic LuFeO$_3$ is a room temperature multiferroic of type-II variety exhibiting quite a strong coupling between magnetization and polarization.Comment: 5 pages with 5 figures; published in Appl. Phys. Let

Development of Materials and Processing Technology for Rural Blacksmiths : A Package

Significant increase in agriculture products has been achieved in India through many avenues like use of better seeds, fertilizer, and irrigation yet less attention has been paid on improvement of the agriculture tools. Better tools and implements accelerate the agriculture product-ion and for this genuine sources of raw materials for implements are in demand. Considerable research work at National Metallurgical Laboratory (NML), Jamshedpur has proved the utility of improved agriculture tools. The traditional practice of rural blacksmiths for producing the tools is being challenged by the growing industries surrounding the villages. Modern industries at the urban sector have lured the rural youths to fill their pockets by the moderate pay packets. So they are eager to switch over to urban side leaving their traditional trades. Since a few of them are succeeded to get absorbed in the modern industries, most of them are forced to return to their villages and here comes the means of survival with the traditional trades unless the production technique is enhanced/updated. Various problems regarding raw mater-ials, education irtconnection with forging, design of implements and their heat treatment have been studied. Major phase of work, carried ou at NML was to provide technology for achieving suitable raw materials by back yard steel melting technique and establishment of appropr-iate forging and heat treatment schedule to meet the speci-fied standards. To provide technological support/ back up to practising blacksmiths of rural sectors, NML has asse-ssed the quality of existing tools and implements and suggested methods for life improvement. Keeping in view the economics, NML has developed a low cost fuel-efficient furnace with a marginal alteration of the existing (Mother earth) hearth furnace used by the rural blacksmiths. The efficiency of the furnace has been enhanced distinctively by reducing convective and radiative heat losses by controlling the pre heated air and natural airflow ratio through the blower. This furnace has such a design that the same can be used for heat treatment of the tools. Simultaneously, a manually operated mechanical hammer is also developed for sledging purpose.With this, blacksmiths can continue the forging operation single handedly with substantial ease and increased productivity

Same sign di-lepton candles of the composite gluons

Composite Higgs models, where the Higgs boson is identified with the pseudo-Nambu-Goldstone-Boson (pNGB) of a strong sector, typically have light composite fermions (top partners) to account for a light Higgs. This type of models, generically also predicts the existence of heavy vector fields (composite gluons) which appear as an octet of QCD. These composite gluons become very broad resonances once phase-space allows them to decay into two composite fermions. This makes their traditional experimental searches, which are designed to look for narrow resonances, quite ineffective. In this paper, we as an alternative, propose to utilize the impact of composite gluons on the production of top partners to constrain their parameter space. We place constraints on the parameters of the composite resonances using the 8 TeV LHC data and also assess the reach of the 14 TeV LHC. We find that the high luminosity LHC will be able to probe composite gluon masses up to similar to 6 TeV, even in the broad resonance regime

Influence of Austempering Temperature on Microstructure and Mechanical Properties of Cast Fe-Si-Mn-VSteel

The present investigation was carried out to examine the influence of austempering temperature on the micro-structure and mechanical properties of a low carbon, high silicon (C-0.13%, Si-1.2%, Mn-1%, V-0.08%) cast steels. The Induction melted casting block was homogenized at 1000°C for 6 hrs. The samples for microstructure and the tens-ile specimens were prepared from the cast steel block according to ASTM standards and were imparted three diff-erent austempering heat treatments to produce different microstructure. The samples are austenitisation at 900°C for 30 minute and then rapidly quenched to a salt bath maintained at temperature 350/400/450°C for 10 minute and then finally air cooled. The microstructure were observed under optical and TEM microscopy. show that UTS decreases but % El increases with increasing apstempering tempe-rature. The 400°C austempering temperature exhibited the best combination of UTS and %EI at room temperature (UTS-663 MPa, EL-26%) with revealing microstructure of bainite and retained austenite