Comparative study of superelastic Ti–Zr–Nb and commercial VT6 alloy billets by QForm simulation

A comparative simulation of hot radial shear rolling (RSR) of billets made of a superelastic Ti–Zr–Nb and a commercial VT6 alloy was performed using the QForm finite element modeling program. Rolling in 48 modes with a variable feed angle and elongation ratio at 4 levels and initial rolling temperature at 3 levels was investigated for each alloy. The Ti–Zr–Nb alloy rheology during hot deformation was determined experimentally by hot upset forging and imported into the QForm program. The presence of maxima on the flow curves at the initial stage of deformation, which are absent in the VT6 alloy, is revealed. Simulation results are presented in the form of fields of the stiffness coefficient, strain rate intensity, cumulative strain degree in the maximum reduction section depending on the rolling mode. General regularities of the Ti–Zr–Nb and VT6 behavior in RSR are similar. The gradient of the fields studied decreases, and the roll pressure and torque increase with an increase in the feed angle and elongation ratio. The initial rolling temperature does not significantly affect the deformation pattern, but it significantly affects the roll pressure and torque. At the same time, the experimental alloy demonstrated the greater tendency to localize deforming forces in the near-contact zone and to increase the gradient of stress-strain state parameters over the billet section. The study of the tightening shape and depth of rolled billet ends showed that the Ti–Zr–Nb alloy has a 3.5–9.6 % greater tightening depth. It is shown that experimental alloy rolling requires 1.6–2.4 times higher roll pressure and torque as compared to the commercial alloy.

The Study of the Ventilation Influence to Gas-Based Direct Reduction Shaft Furnace Flow Field

Direct reduced iron (DRI) shaft furnace flow field has important influence to the DRI production process, and the ventilation is a key factor for the velocity and pressure distribution of the gas flow in the furnace. At present works, the direct reducing gas velocity distribution and pressure distribution of DRI shaft furnace were studied with different ventilation. By the analysis of numerical simulation, the result was found that the direct reducing gas velocity increase with height in the shaft furnace reduction section. The velocity of the direct reducing gas augment with the increase of ventilation. The direct reducing gas pressure add with increasing height in the shaft furnace reduction section. With ventilation increasing, the pressure of the shaft furnace ventral part increase, and the pressure gradient increase in the direction of height in the DRI shaft furnace.

Substance and Function in Chemical Research

When chemical instruments are used in the laboratory, a specimen undergoes changes at the microscopic level. Depending on the instrument, the specimen absorbs or emits radiation. Alternatively, radiation is scattered, refracted, or diffracted. We often read that microscopic events produced from chemical instrumentation are real, as opposed to mere artifacts of the experiment. But exactly what does this mean? This philosophical question underlies a continual dilemma for the experimental chemist, whether to declare triumphantly that his/her findings reveal some insight about a chemical substance or to refrain from such a judgment for fear of having produced a mere artificial effect. Of course, a commonplace position is that the artificiality of laboratory techniques can be separated, in principle, from the real effects, because these techniques enable scientists to break the influence of laboratory constructions on experimental “ facts.” But some commentators have resurrected the fairly skeptical view that such declarations of success are grossly overstated because the interference from various instrumental techniques, laboratory equipment, and theoretical ideas precludes the possibility of exposing properties of independently existing substance. If we address this philosophical question by exploring techniques of chemical instrumentation, we find that the categories of a laboratory artifact and real effect are not mutually exclusive. As I argue here, the experimental phenomena of chemical research are both real and artificially produced from laboratory apparatus, manufactured conditions, and sophisticated techniques of researchers. The plan of this chapter is as follows: examine the character of analytical instruments in chemistry (section 1); explain the difference between an artifact and a real effect (section 2); examine the process of virtual witnessing in chemistry (section 3); explore how instruments are designed to mimic known chemical or physical processes (section 4); introduce the philosophical importance of noise-blocking techniques (section 5); and conclude with brief remarks about experimental reduction (section 6). The similarities and differences between absorption spectroscopy and Raman spectroscopy are discussed. In this chapter I adopt a functional orientation to our understanding chemical substance, according to which a specimen is known by those capacities that technicians try to exploit during laboratory research.