Finite-element simulation of semi-solid metal processing of tool steel encased in carbon steel

The semi-solid metal processing allows for the production of components with complex geometries allied to lower forming forces. In the case of X210Cr12 tool steel, one big advantage of semi-solid metal processing is that it produces a microstructure free of precipitated chromium carbides, resulting in higher resistance to cyclic stresses. However, the application of this process in steels is limited until now due to technical difficulties, such as high temperatures, the necessity of a precise control of temperature, and the narrow liquidus–solidus range. For that reason, a preliminary numerical assessment of the forming procedure is highly welcome, in order to reduce potential errors in the final component. In this paper, we propose a methodology for the numerical simulation of semi-solid metal processing in steel samples under hot compression. We show that it is possible to use multilinear hardening plasticity models whose only input are the flow stress curves of each material. We also show that it is mandatory that these experimental curves are obtained through tensile tests performed at the same temperature as the working/simulated component. To validate the methodology, a full-scale experiment is undertaken so that the deformed sample can be compared to the numerical results. It is concluded that the methodology is suited for the assessment of mechanical quantities during the finite-element analysis of semi-solid processing of steel.

THE EFFECT OF VARIATIONS OF LEAD METAL SOLUTION PH VARIATIONS ON ADSORBENT FROM TIRTA MUSI WASTE MUD WASTE PALEMBANG

Industrial waste can cause environmental pollution, one of which is solid metal waste. Lead is a dangerous and toxic heavy metal that can cause damage to the surrounding environment. Liquid waste containing mercury in industry contains a mixture of chemical compounds that other This causes the pH of the solution in the waste to vary. Lead metal waste needs to be treated with method one of which is the absorption of waste using an adsorbent. To enlarge the pores, the adsorbent will be activated using a 2 M KOH solution with the selected adsorbent, namely the sewage sludge of PDAM Tirta Musi Palembang which contains PAC (Poly Aluminum Chloride) which can help optimize absorption. The level of metal degradation was analyzed using AAS with absorption parameters obtained 4 with an absorption capacity of 23 ,22 mg/g.

Hydrogen diffusion under the effect of stress and temperature gradients

In this paper, a finite element (FE) model is developed to investigate lattice hydrogen diffusion in a solid metal under the influence of stress and temperature gradients. This model is applied to a plate with a circular hole which is subjected to temperature and hydrogen concentration gradients. It is demonstrated that temperature gradients significantly influence hydrogen diffusion and hence susceptibility to hydrogen embrittlement when utilizing hydrogen for gas turbines.

Transcranial electrical stimulation devices

Transcranial electrical stimulation (tES) devices apply electrical waveforms through electrodes placed on the scalp to modulate brain function. This chapter describes the principles, types, and components of tES devices as well as practical considerations for their use. All tES devices include a waveform generator, electrodes, and an adhesive or headgear to position the electrodes. tES dose is defined by the size and position of electrodes, and the waveform, duration, and intensity of the current. Many sub-classes of tES are named based on dose. This chapter focuses on low intensity tES, which includes transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial pulsed current stimulation (tPCS). tES electrode types are reviewed, including electrolyte-soaked sponge, adhesive hydrogel, high-definition, hand-held solid metal, free paste on electrode, and dry. Computational models support device design and individual targeting. The tolerability of tES is protocol specific, and medical grade devices minimize risk.

Digital Technologies for Aerospace Industry Products

The creation of new generations of products in the aerospace industry is possible by applying a fundamentally new method of designing and manufacturing solid metal multilayer monocoque. A new additive manufacturing technology based on Russian patents is proposed.

Heterogeneous Metal Catalysis for the Environmentally Benign Synthesis of Medicinally Important Scaffolds, Intermediates, and Building Blocks

: This account provides a broad overview of the application of solid metal catalysts in synthetic chemistry with a focus on the synthesis of medicinally important scaffolds or building blocks. Heterogeneous catalysis is a fundamental contributor to green or sustainable synthesis. Despite this, many synthetic chemists overwhelmingly focus on homogeneous methods, and due to their unfamiliarity with solid catalysts, many would not consider using them. The primary purpose of this work is to bring solid catalysts and their application possibilities to the attention of synthetic chemists in a format that focuses on reactions, thus building a bridge between the two sides for the benefit of sustainable applications and, eventually, the whole society. The two major parts of this account describe the common types of solid metal catalysts and the applications of these catalysts in sustainable synthesis. The first part gives an overview of the major types of solid metal catalysts, including common hydrogenation catalysts to metal nanoparticles. The second and more extensive part illustrates the use of these catalysts in a thematic order based on reaction types, including hydrogenation, hydrogenolysis, oxidation, metathesis, cross-coupling reactions, and hydroformylation.

‘Adding to the Good Silver with Other Trickery’ : Purity and Contamination in Clement VII’s Emergency Currency

In early modern sites of smithing and minting, the point of flux – when solid metal became liquid – was always opportune for contamination and deceit. The reputations of metalworkers could turn on it. In chaotic, unregulated circumstances, the handling of molten gold and silver became even more suspect. This essay considers purity and contamination with respect to two acts of metallic transformation during the Sack of Rome in 1527, when papal treasures were melted down to consolidate financial assets and produce emergency currency. In addition to the expected anxieties surrounding the fineness of gold and silver in these circumstances, the two events also suggest an alternate conception of metallic purity that takes into account metal’s protean transit between forms.