Production and Characterization of Austenitic Stainless Steel Cast Parts Reinforced with WC Particles Fabricated by Ex Situ Technique

In this work, austenitic stainless steel specimens were locally reinforced with WC particles. The reinforcements were fabricated via an ex situ technique based on powder technology. Mixtures of WC, Fe, and M0101 binder were cold-pressed to obtain powder compacts. After debinding and sintering, the porous WC–Fe inserts were fixed in a mold cavity, where they reacted with liquid metal. Microstructural analysis was conducted for characterization of the phases constituting the produced reinforcement zone and the bonding interface. The results revealed that the reinforcement is a graded material with compositional and microstructural gradients throughout its thickness. The zone nearest to the surface has a ferrous matrix with homogeneously distributed WC particles and (Fe,W,Cr)6C and (Fe,W,Cr)3C carbides, formed from the liquid metal reaction with the insert. This precipitation leads to austenite destabilization, which transforms into martensite during cooling. A vast dissolution of the WC particles occurred in the inner zones, resulting in more intense carbides formation. Cr-rich carbides ((Fe,Cr,W)7C3, and (Fe,Cr,W)23C6) formed in the interdendritic regions of austenite; this zone is characterized by coarse dendrites of austenite and a multi-phase interdendritic network composed of carbides. An interface free of discontinuities and porosities indicates good bonding of the reinforcement zone to stainless steel.

Integrating Sustainability into Material Management Practices

Modern Society followed, and it is still largely following, a linear process for natural resources utilization: raw material extraction, goods manufacturing, use/consumption, waste generation. Such a model is proven to be not sustainable because it cannot go forever considering the limited quantity of available resources on Earth but also because of waste and process by-product management. A multitude of diverse initiatives to change this process started at different levels and within several industries in the last years including the O&G sector. Most of these initiatives share the same principle of "regeneration": waste and materials represent, in this view, the "feedback loop" able to make the production process a circular process, instead of an open-end one. Eni promotes and supports different initiatives to implement the principles of a Circular Economy and the objective of this paper is to describe a process implemented within Eni aimed at reducing the footprint of the Oil and Gas Industry with reference to material usage. Surplus and damaged materials are no more treated as waste, but they are re-engineered or re-conditioned (if necessary) in order to be redeployed to other projects within Eni affiliates all around the world. Nowadays this process is well structured and formalized within Eni and it is extensively applied involving all worldwide affiliates, reducing the overall CO2 footprint. Results achieved within Eni, in the last few years, averages between 6,500 and 17,500 ton of steel of material redeployed among Eni's affiliates for a value ranging between 26 and 71 million USD. The overall average result is 23,000 CO2 equivalent ton not released per year and 242,000 GJ of energy saved (ref. to steel manufacturing estimated impact:1.9 ton di CO2/ton steel cast and 20 GJ/ton steel cast). Extending this process to involve material and equipment manufacturers, it is possible to improve the whole supply process reducing at the "source" the material storage needs, the material surplus and the produced wastes, including the CO2 emission produced in the transport phase. Initiatives like "Just in Time" delivery and material "Buy Back", mainly applied in Countries where Framework Agreements are already in place between Eni and its manufacturers and where manufacturers have their production sites and other facilities, are essential to achieve this target. Eventually, applying the approach to the whole supply chain and operations management will allow to reduce the "last mile" warehousing and transportation needs, including the dimension and capability of the operations fleet.

ESTIMATION OF ACCURACY OF COORDINATED SMALL DIAMETER HOLES WITH CUTTING TOOL DIRECTION

The dimensional analysis of the initial parameters of the coordinated dimensions of the holes is presented. Issues related to the assessment of the accuracy of the location of the surfaces of deep holes are considered. The influence of various technological factors on the magnitude of scattering of coordinated dimensions is studied. Experimental studies using experimental design methodology, which was used for sample preparations 45 steel, cast iron SCH15, aluminum alloys. Factors such as the cutting angle, the hardness of the workpiece, the cutting force and their effect on the diameter of the impression and its depth were studied. As a result of the experiments, a slight effect of the drilling force on the diameter and depth of the impression was found. However, it was found that the angle of the core leads to a directly proportional increase in the diameter of the imprint and inversely affects its depth. The hardness of the material has a more significant effect on the diameter of the imprint than on its depth. The total influence of controlled factors significantly affects the diameter of the imprint. Minimum core drilling angles are proposed for some materials. A mathematical model of the accuracy of machining coordinated holes is proposed on the basis of estimating the coefficients of the regression equation and finding the required mathematical models of the scattering fields of dimensions and deviations. As factors that vary during the drilling of coordinated holes, were taken: the length of the conductor sleeve, the departure of the tool, the hardness of the workpiece, the diameter of the tool. It is found that with increasing tool diameter and guide sleeve length decreases the amount of dimensional scattering from the base and positional deviations, and increasing tool departure and improving the physical and mechanical properties of the workpiece increase the size of the size scattering field from the base and positional deviation. An additional factor was introduced: the gap in the combination between the cutting tool and the conductor sleeve and obtained mathematical dependences of the influence of factors on dimensional accuracy when machining deep holes with the direction of the cutting tool. It is shown that the introduction of an additional factor - the gap, did not change the essence of the process of errors on small aggregate machines, and the change in diameters does not lead to a significant increase in scattering fields.

Comparative analysis of the structure of solid and hollow steel cast billets

This paper presents the research results of solid structure and hollow steel billets obtained by continuous casting. To substantiate the feasibility of using a hollow billet as an initial one in the production of seamless hot-rolled pipes, a comparative analysis of the distribution of non-metallic inclusions, macro- and microstructure, as well as segregation by structural zones was carried out. When analyzing the macrostructure of a hollow billet, two distinct zones were revealed: equiaxed small and columnar crystals, which distinguishes it, compared with a solid billet, by the absence of a zone of misoriented crystals. This, in turn, helps to eliminate defects such as axial porosity and segregation. The improved quality of the macrostructure during casting of a hollow billet is explained by more favourable conditions for heat removal and a higher rate of solid-phase advance due to bilateral cooling, and less shrinkage of the melt due to its cross-sectional geometry. The distribution of nonmetallic inclusions, consisting of oxide, sulfide and oxysulfide compounds, and liquidation elements, showed that they are concentrated mainly at the boundaries of crystalline zones, and for a solid billet and in the central part. This fact is caused by the development of a zone of intense heat removal. When research the microstructures of solid and hollow workpieces, a ferrite-pearlite mixture is observed in both cases. The microstructure of the hollow billet is more dispersed, which is confirmed by durometric measurements.

Neuro-Fuzzy System for Compensating Slow Disturbances in Adaptive Mold Level Control

Good slow disturbances attenuation in a mold level control with stopper rod is very important for avoiding several product defects and keeping down casting interruptions. The aim of this work is to improve the accuracy of the diagnosis and compensation of an adaptive mold level control method for slow disturbances related to changes of stopper rod. The advantages offered by the architecture, called Adaptive-Network-based Fuzzy Inference System, were used for training a previous model. This allowed learning based on the process data from a steel cast case study, representing all intensity levels of valve erosion and clogging. The developed model has high accuracy in its functional relationship between two compact input variables and the compensation coefficient of the valve gain variations. The future implementation of this proposal will consider a combined training of the model, which would be very convenient for maintaining good accuracy in the Fuzzy Inference System using new data from the process.

ANALYSIS OF REGRESSION MODELS OF STRENGTH AND PLASTIC PROPERTIES OF DEFORMATION-THERMALLY HARDENED REINFORCING PROFILE

Numerous studies have shown that the processes of structure formation as aresult of the combined effect of plastic deformation and phase transformations onthe alloy are different from the formation of the structure during conventional heattreatment and provide a high set of mechanical properties that cannot be achievedby conventional methods of heat treatment or complex alloying.Сurrently, in the production of rod reinforcement for reinforced concretestructures, technologies of combined deformation and thermal hardening areincreasingly used. When hot rolling is combined with subsequent heat treatment,intensive and controlled cooling of hotly deformed austenite is performed directlyat the exit from the finishing stand of the rolling mill, which leads to a stronggrinding of the structure, and, consequently, provides high mechanical propertiesof the material than when cooling in air, as was the case at many existing rollingmills.Analytical review of the literature on the problem of combining hotdeformation with heat treatment shows that the efficiency of deformation and heattreatment depends on the temperature of rolling, the total degree of fragmentationand deformation, the degree of a single strain, time interval from the end of hotrolling to the beginning of accelerated cooling, duration of intensive coolingdefines the temperature smoothback, like the original steel (cast or rolled), andfinally, the chemical composition of the processed steel [1].

3D Transient Spray Cooling Heat Transfer Simulation for Metallic Slabs of Various Alloys

Water spray cooling is widely used in many industrial processes to control the surface dissipation of a material ported at high temperatures. To predict heat transfer and obtain the rate of required temperature distributions of the surface, it is necessary to understand the basic spray cooling dynamics and a more precise estimation of the heat transfer rate. This paper is about a three-dimensional simulation to estimate the transient heat transfer obtained locally by water spray to reduce the temperature of heated metal. The use of water spraying is a practical and flexible process. It is possible to vary, in space, time, and in large proportions the flux of extracted heat and controls the density of the flow of water which is a key element and very simple to achieve. Globally, the aim of this study is to simulate the spray cooling of different metal slabs for various alloys (steel, cast iron, titanium, nickel) by mainly comparing cooling in maps of iso-surfaces and in curves (at starts and globally) obtained after estimation of the heat flux.

Redesign Mata Bor Tanah Untuk Pembuatan Lubang Biopori Di Desa Puron, Kecamatan Bulu, Kabupaten Sukoharjo

<p><em>The lack of rainfall and the absence of catchment areas are the main factors of the lack of water in Puron Village. Making biopori becomes solutive because it is useful for water absorption, reducing standing water, composting containers, and fertilizing the soil. Artificial biopores are made by making holes in the ground using tools such as crowbars or using ground drilling machines. The use of aids model adapted to the drill bit based on the state of the soil contour. This research is focused on classifying drill bits and redesigning which is in accordance with the condition of the soil environment in Puron Village, Bulu District, Sukoharjo Regency. So that biopori holes can be created more effectively and efficiently. The research method was carried out through the classification of tool drill bits through the house of quality product (HOQ) and redesign using Autodesk Fusion 360 software application. It was found that the design with a screw drill model with a pointed spiral has a high product quality value and can applied in puron Village. The design of the drill bit by adjusting the contours of the Puron Village can make a 100 mm diameter biopori hole. The design specifications of the drill bit with steel cast with 12 spiral plates with a length of 1300 mm with a diameter of 115 mm can be driven with a 10 HP engine. The design results have maximum stress, displacement, reaction force and strain of 3.62 MPa, 0.00081 mm, 0.35 N, and 0.000015.</em></p>

Monumental Misunderstandings

A statue of stainless steel cast in China and placed at the entrance of the new National Stadium in Mozambique sparked controversy between Chinese donors and Mozambican recipients in the period leading up to the stadium’s 2011 inauguration. Based on ethnographic fieldwork among the Mozambican and Chinese nationals involved in the project, we explore the multiple misunderstandings surrounding the statue and show how they came to define Sino-Mozambican relations. Entextualized through materiality, the misunderstandings assumed a monumental form in the statue, and the message of mutual incomprehension continued to reverberate across the social terrain of Sino-Mozambican relations long after the statue itself had been removed. Misunderstandings, we argue, should not be dismissed as ephemeral communicative glitches, but seen as productive events that structure social relations.