Metallurgical & Materials Engg

Navy C-Ring test parts were made of AISI 1022, 4320, 8625, and CF8M steels and heat treated in a designed experiment to evaluate the commercial heat treatment distortion simulation software DANTE. The parts were machined and then measured with a CMM for original dimensions. The parts were then heated and subsequently quenched in two different immersion orientations in agitated water. Temperature measurements were taken from the austenitic stainless steel parts to obtain heat transfer coefficients for the simulations. The part dimensions were re-measured and compared to pre-heat treatment values. The CF8M experiments show that the gap in the C-Ring closes due to thermal stresses. The cast carbon and low-alloy steel C-Rings resist the closure somewhat, though general trends toward closure are still apparent. This is in contrast to results shown in previous literature. The dimensional measurements for the different immersion directions and different alloys are compared and discussed. While the DANTE simulations are able to capture the general distortion trends seen in the experiments, they are not in complete agreement with the experimental results obtained here. Recommendations are made for future work.

Cryogenic Treatment is the subzero process, carried out directly after quenching and proceeded by successive tempering. In cryogenic treatment materials are treated at-196 o C for a soaking period of 24 hours. It has shown significant changes in the microstructure and mechanical properties of materials. The improved mechanical properties are imputed to the low temperature conditioning of martensite in ferrous metal such as tool steel and second phase precipitation in non ferrous metal such as aluminum and magnesium alloys. This review paper aims at explaining about the history, research and development in cryogenic treatment along with its applications.

Navy C-Ring test parts were made of AISI 1022, 4320, 8625, and CF8M steels and heat treated in a designed experiment to evaluate the commercial heat treatment distortion simulation software DANTE. The parts were machined and then measured with a CMM for original dimensions. The parts were then heated and subsequently quenched in two different immersion orientations in agitated water. Temperature measurements were taken from the austenitic stainless steel parts to obtain heat transfer coefficients for the simulations. The part dimensions were re-measured and compared to pre-heat treatment values. The CF8M experiments show that the gap in the C-Ring closes due to thermal stresses. The cast carbon and low-alloy steel C-Rings resist the closure somewhat, though general trends toward closure are still apparent. This is in contrast to results shown in previous literature. The dimensional measurements for the different immersion directions and different alloys are compared and discussed. While the DANTE simulations are able to capture the general distortion trends seen in the experiments, they are not in complete agreement with the experimental results obtained here. Recommendations are made for future work.

Deep cryogenic treatment is an add-on process to conventional heat treatment in which material is treated at cryogenic temperature. The mechanical properties of the tool steel are significantly improved by Deep Cryogenic treatment. Surface integrity and dimensional stability is having greater impact on the functional performance of the tool during service conditions. The objective of this work is to investigate the effect of deep cryogenic treatment on the surface integrity and dimensional stability of the D2 tool steel. The metallographic samples and Navy C Rings of D2 Tool steel were treated at cryogenic temperature of-193 0 C after hardening and tempering. Results have shown improvement in surface roughness. The improved surface roughness is attributed to the release of tensile residual stresses and more precipitation and uniform distribution of fine secondary carbides. DCT have higher shape distortion than CHT. The distortions in DCT can be attributed to the section sensitivity of D2 Tool steel.

Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization goes beyond the traditional aim of capacity maximization, contributing also for organization's profitability and value. Indeed, lean management and continuous improvement approaches suggest capacity optimization instead of maximization. The study of capacity optimization and costing models is an important research topic that deserves contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization's value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization might hide operational inefficiency.

In-feed centerless grinding technique offers a major contribution to the industries. This is the alternative in-feed centerless grinding technique using regulating wheel. Mainly centerless grinding is divided in three types, and those are End feed, in-feed and through feed Centerless grinding. This paper mainly deals with low cost automation on in-feed Centerless grinding machine using regulating wheel suitable for multiple in-feed type jobs. It deals with the development of a Centerless grinding automation technique for the job having multiple diameter, steps or projections on the job. In this new method of automation hydraulic cylinders, sensors besides a control panel, pressure gauge, and a hydraulic power pack added. Relay control is used for the electrical control. The objective of this work is to reduce the cycle time, consistency in the quality of job and to reduce the production cost. In this focus is concentrated on compact centerless grinding unit. The higher machining acc...

A new approach for the design of alloy systems with multiprincipal elements is presented in this research. The Al x CoCrCuFeNi alloys with different aluminum contents (i.e., x values in molar ratio, x ϭ 0 to 3.0) were synthesized using a well-developed arc-melting and casting method. These alloys possessed simple fcc/bcc structures, and their phase diagram was predicted by microstructure characterization and differential thermal analyses. With little aluminum addition, the alloys were composed of a simple fcc solid-solution structure. As the aluminum content reached x ϭ 0.8, a bcc structure appeared and constructed with mixed fcc and bcc eutectic phases. Spinodal decomposition occurred further on when the aluminum contents were higher than x ϭ 1.0, leading to the formation of modulated plate structures. A single ordered bcc structure was obtained for aluminum contents larger than x ϭ 2.8. The effects of high mixing entropy and sluggish cooperative diffusion enhance the formation of simple solid-solution phases and submicronic structures with nanoprecipitates in the alloys with multiprincipal elements rather than intermetallic compounds.

This work explores the idea of predicting metallic glass forming composition in a multi component alloy for which an equilibrium phase diagram is yet to be deciphered. Deep eutectic regions in a quaternary alloy (ZreTieCueNi) have been extrapolated to the quinary ZreTieCueNieAl system for designing a potential bulk glass forming composition. P HSS parameter which is the product of mixing enthalpy, mismatch entropy and configurational entropy of an alloy, has been utilized for thermodynamic modeling. P HSS values are computed through substitution of Al into the each of the fifteen quaternary eutectics that have been reported in the literature in the ZreTieCueNi system. A good correlation of P HSS range between modeled alloys and established glass formers indicates the subtle efficacy of this method for high entropy amorphous alloy design through a rationale thermodynamic approach.

The available glass forming ability criteria have been examined by classifying them into four basic categories depending on critical temperatures, thermodynamic quantities, topological and kinetic aspects of glass forming alloys. A large number of glass forming alloys of widely varying natures and origin have been analysed with their experimentally measured properties to assess their glass forming ability. A novel approach using kinetic viscosity of glass forming alloys obtained by the Vogel-Fulcher-Tamman equation and the critical cooling rate calculated from the TTT diagram is demonstrated as an excellent universal glass forming ability criterion. Moreover, thermodynamic and topological modelling results through computation of a novel P HSS parameter for various alloy compositions spanning different alloy systems have rendered qualitative guidelines on propensity for glass formation in multicomponent alloy systems. Besides, the importance of kinetic interpretation of P HSS range observed for glass forming alloys is also elaborated.

Bulk metallic glasses (BMGs) are currently the frontiers in structural materials due to their enhanced mechanical properties in comparison to conventional crystalline alloys [1]. They exhibit high yield strength and high resilience [2] suitable for micro electro mechanical systems (MEMS) applications that enable sensing and actuation in diversified industrial products. In addition to their superior hardness and outstanding corrosion resistance they can be formed into intricate shapes through thermoplastic deformation. The formability of these materials in the super cooled liquid region is facilitated by steady Newtonian flow at low stresses that render super plastic deformation .The ability to fabricate into the form of nanowires, foams and honeycombs enabled application of amorphous alloys in domains that require large energy absorption ability and room temperature plasticity [1]. Currently, many novel metallic glasses (MGs) based materials like metallic glass matrix composites, transformation induced plasticity MG composites and shape memory BMG composites are being developed in order to harness their exquisite mechanical and functional properties for technological applications .

Aluminium based Metal Matrix Composites (AMCs) are amongst the most sought after materials for aerospace structural applications as they synergize large ductility of Al with higher strength of reinforcements. AMCs typically contain ceramics in the form of fibers, flakes or particles as reinforcements and are marred by lower wettability of filler with the matrix in addition to unfavorable interfacial reactions; thereby leading to tradeoff between strength and ductility from a material designer viewpoint. Hence there exists a pressing need to develop an alternate reinforcement material that obviates the above problems and also result in a light weight AMC. In the current materials research paradigm, High Entropy Alloys (HEAs) have been predicted to possess remarkable functional and structural properties. Moreover in various recent scientific reports, Metallic Glass (MG) reinforcements have been reported to have excellent compatibility with Al matrix and also resulted into enhancement in yield strength of the AMCs. In this paper through thermodynamic modeling using PHSS parameter it is endeavoured to predict metallic glass formation in high entropy regime for Mg-Cu-Zn-Y quaternary system with the aim to harness excellent structural properties of both HEAs and MGs along with Al matrix.

Austenitic stainless steels are widely used in high performance pressure vessels, nuclear, chemical, process and medical industry due to their very good corrosion resistance and superior mechanical properties. However, austenitic stainless steels are prone to sensitization when subjected to higher temperatures (673 K to 1173 K) during the manufacturing process (e.g. welding) and/or certain applications (e.g. pressure vessels).