This work deals with the application of the Conform SPD (Severe Plastic Deformation) continuous extrusion process for ultrafine to nanostructured pure titanium production. The process has been ...derived from the Equal Channel Angular Pressing (ECAP) technique but, unlike ECAP, it offers continuous production of high-strength wire. This study describes the Conform SPD process combined with subsequent cold working (rotary swaging technique), its potential for commercial application, and the properties of high-strength wires of pure titanium. High-strength wire of titanium Grade 4 is the product. Titanium Grade 4 reaches ultimate strengths up to 1320 MPa. This value is more than twice the ultimate strength of the unprocessed material. The typical grain size upon processing ranges from 200 to 500 nm. Process development supported by FEM analysis together with detailed microstructure characterization accompanied by mechanical properties investigation is presented.
Developing an open-die forging process for a poor-workability alloy has always been a challenge. This paper presents a rapid method that meets this purpose. A simplified forging test was considered ...for assessing the limit states of material in open-die forging. It can be employed in industrial forge shops. A V-shaped testing die was designed using finite element (FE) simulation. The V-shape geometry is convenient for strain evaluation. Rectangular blocks will be tested across a wide range of working temperatures. Based on the test results, limit states can be identified. Then friction testing method was optimized. It is also simple comparison test. Both technological tests are suitable for determination of optimized parameters in forging. The risk of material failure can thus be eliminated or minimized.
The presented work is aimed at developing a mould geometry suitable for casting both low- and high-alloy steel grades into 500 kg experimental ingots. The high Height-to-Diameter (H/D)-ratio mould ...currently used in COMTES FHT Inc. served as a reference and for finite element method simulations (FEM) of the filling and solidification process. The optimized mould geometry, balancing the porosity and segregations, was determined using MAGMA software. Four different steel grades were defined for the simulation. Case studies were carried out for 34CrNiMo6 (W.Nr. 1.6582), DHQ8, CB2 and borated stainless steel grades ranging from low-alloy steel to high-alloy steel. Extended user-defined criteria and verified boundary conditions were used to predict the formation of A-segregations in cast steel. Both primary (PDAS) and secondary (SDAS) arm spacings were modelled as well. The optimized mould shape and the casting assembly were designed based on the simulation results.
The presented work is aimed at the evaluation of the cold bending capacity of high-borated austenitic stainless steel sheets. Due to their excellent neutron-absorbing capability, borated stainless ...steels belong to the group of tailor-made structural materials widely used for vertical storage baskets for holding spent nuclear fuel assemblies in cooling pools at dry or wet storage facilities. The basket consists of individual fuel assembly cells. Each polygonal cell is usually welded from several steel strips. It would be advantageous to use bent steel semi-product to avoid welded seams as much as possible. Welded seams are difficult to make, and moreover, they are susceptible to corrosion. However, high-borated stainless steels, because of their boron content, show limited hot and cold workability. Thus, their cold bending capacity would be the primary issue. Their austenitic matrix with embedded hard and brittle boride particles is prone to the evolution and fast propagation of dimple transgranular fracture. This work is focused on the bending aspects of borated steel sheets with respect to the most commonly used hexagonal cell geometry. Experimental results provide practical recommendations for the rack design. The damage criterion has also been proposed using FEM simulations in DEFORM®.
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•Theoretical calculations (DFT, MP2) of indole were performed.•Thirty-seven rotational transitions with hyperfine quadrupole structure were measured.•Molecular constants of indole are ...presented.
Every single person has a certain characteristic group of scent molecules. The microwave spectra of the organic compounds of scent could be useful for the identification of people, but a database of spectra of scent molecules needs to be created first. The spectrum of indole, that is among the human scent molecules, was measured in the frequency range of 7.5–19GHz under the conditions of supersonic expansion in a pulse emission Fourier Transform Microwave Spectrometer (FTMW) with a Fabry-Perot resonator. The high resolution of the spectrometer enables the detection of rotational transitions with hyperfine splitting. A total of 37 new rotational transitions were measured and analyzed using the PGOPHER software to derive the rotational and centrifugal distortion constants, as well as the 14N nuclear quadrupole coupling constants. The molecular constants were determined with approximately two orders of magnitude greater accuracy as compared with some earlier studies of indole. The obtained data and constants of indole are the first step towards the development of a database of the human scent molecules.
This recent study deals with the optimization of the mechanical performance of Grade 2 and Grade 4 titanium with Conform severe plastic deformation (SPD) processing and subsequent rotary swaging. A ...comprehensive study of the materials behaviour and characterisation during and after processing is given by (finite element method - FEM) numerical simulation, microscopy methods and mechanical testing. The mechanical and fatigue properties are discussed in terms of texture and microstructure evolution. It is shown that the combination of Conform SPD and rotary swaging is a promising technique for economically reliable, high-gain production of titanium alloys fulfilling requirements for biomedical applications. Such a processing can improve the mechanical properties of the unalloyed titanium to the level of the commonly used Ti-6Al-4V.
The paper describes the development of austenitic steel with the TWIP effect, which is alloyed with chromium to increase corrosion resistance. The experimental heat of this steel was cast in an ...experimental melting furnace and subsequently subjected to hot and cold rolling. After cold rolling, the appropriate recrystallization annealing temperature was applied to obtain the optimal austenitic grain size. X-ray diffraction proved that the steel contains a fully austenitic structure. After recrystallization annealing, the sheets achieved a TS of more than 950 MPa with an elongation of 40%. The corrosion resistance of this steel is increased with the addition of chromium.
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