Numerical study on the plastic deformation behavior of AZ31 magnesium alloy under different loading conditions

Based on the stress characteristics of the instantaneous cross-section deformation of the wall reducing section during the cold rolling of two-roll Pilger pipes, the rectangular samples with 0° and 90° to the extrusion direction (ED) were cut from the extruded AZ31 magnesium alloy bar for 3% pre-deformation test to simulate its stress state equivalently. The sample was then cut from the pre-deformed sample by wire cutting for secondary compression, and the sample that is not pre-deformed is selected. The mechanical behavior and texture evolution of AZ31 magnesium alloy under different loading conditions were respectively studied by EBSD experiment and VPSC simulation. Results show that the true stress–strain curve and texture evolution characteristics of AZ31 magnesium alloy during the secondary compression process are in good agreement with the prediction of the VPSC model. The secondary compression behavior can be effectively explained by the relative activity of the deformation modes. The pre-deformation in the ∥ED (⊥ED) direction is conducive to the shift of the pole density of the {0001} basal surface texture to the positive and negative directions of the ED (TD). The pre-deformed sample exhibits a higher yield strength than the non-pre-deformed sample in the same loading direction. The high ductility of magnesium alloys can be achieved by activating pyramidal 〈c + a〉 slippage.

Orientation Analysis

Simple figures illustrate the basic concepts: orientation, Euler angles, Euler space, orientation density function, pole density function. The iteration that decisively influenced the development of orientation analysis follows directly from the relationship between the two density functions. The minimum principle defines the initial function and the structure of the iteration. Using model orientation density function, we prove that this kind of orientation analysis is extremely effective.

Short Communication: Population structure and habitat characteristics of Goniothalamus macrophyllus in Bukit Pembarisan forest, West Java, Indonesia

Adhya I, Widodo P, Kusmana C, Sudiana E, Widhiono I, Supartono T. 2020. Short Communication: Population structure and habitat characteristics of Goniothalamus macrophyllus in Bukit Pembarisan forest, West Java, Indonesia. Biodiversitas 21: 1130-1135. Goniothalamus macrophyllus (Blume) Hook.f. & Thomson is a forest species with important medicinal value and widely used by many local communities. Excessive harvesting of this species has led to population decline and may lead to extinction. The aims of this research was to investigate population structure, habitat characteristics and environmental factors affecting local densities of G. macrophyllus in Bukit Pembarisan forest, Kuningan District, West Java, Indonesia. Purposive sampling was conducted at 17 locations during November 2017 to March 2018. The result showed that the population structure in the study area was dominated by seedlings (95% of the total number of individuals), followed by saplings (4%) and poles (0.1%). Seedlings, saplings, and poles were found growing across a wide elevational range (432-1,273 m asl.), at temperatures of 19-25°C, relative humidity of 80-90%, and soil pH of 4.61-6.46. The multiple regression analysis showed that soil nitrogen and soil pH affected seedling density, whereas soil clay content affected pole density. Our findings indicate that G. macrophyllus preferred acidic soils with high nitrogen and high clay content. We therefore recommend that future conservation efforts include the maintenance of existing poles, a prohibition on bark harvesting, and encouraging use of the leaves, rather than bark, for medicinal applications among consumers of G. macrophyllus.

Changer in the texture orientation of electrolytic nickel by cold air plasma

The effects of cold air plasma influence on the change in the microstructure, stress state and texture of the cathode nickel brand H-1 were studied. By the method of target metallography it has been established that the microstructure does not change under exposure to the cold air plasma. A decrease in the level of micro- and macrostress is shown. By the method of inverse pole figures it has been established that the pole density of the orientations (111), (200) and (311) decreases when exposed to plasma; orientation (311) changes the least intensively. The pole density of the orientation (220) increases from 4.42 in the initial state to 13.3 after plasma treatment, which means an increase in the electrolytic deposition texture. The causes of the observed effects are being discussed. It is assumed that the changes introduced by the plasma occur at a scale level that is much smaller than the size of the coherent scatter blocks.

The Eksperimentation Study of Wave Transmission Trough Type Of Hollow Cube Breakwater

Erosion that occurs in break water by wave sand currents is a serious problem along coastal and inland shore [1]. This study aimed to assess the effect of the model height (Hm) and the pole density on the model on the reduction of the wave height and on the relationship between the non-dimensional parameter. The research was experimental with 2D physical model simulation which was conducted in the laboratory of Marine Engineering Faculty, Hasanuddin University. Several of configurations of Hollow-type breakwater models were made with different densities and model heights. The model scale use was 1:10 for the three model variations ((M1KB, M2KB, and M3KB) with the variations of the periods and of the wave height, at 0,25 m water depth. The research results indicated that the parameters which showed significant effects were the model height and the model density. These parameters showed the t

Diffraction-Based Investigation Methods in Analysing Plastic Strain Zone Underneath Fracture Surface

We used samples of the ВТ41 two-phase titanium alloy to estimate the relationship between testing temperature, KCV fracture toughness values, width of the plastic strain zone and its formation specifics. We developed an efficient method of estimating the plastic strain zone width, based on a special X-ray imaging geometry enabling a high degree of locality for measuring variations in the X-ray line broadening when moving away from the fracture surface. We studied material texture close to the fracture zone and at a distance from it, which allowed us to detect the specifics of grain reorientation, in particular, texture diffusion and an increase in the concentration of basal and prismatic planes parallel to the fracture surface as a result of plastic strain and dislocation saturation. We hypothesise that pole density in the [0001] region grows due to the [1012]-oriented grain slip, while in the region around [1010] pole density grows due to slip of the grains whose orientation is close to [1120]. We verified our X-ray texture analysis data by texture analysis via electron backscatter diffraction (EBSD).

On Structural Aspects of Texture Changes During Rolling of Zr-2.5%Nb Alloy

Using X-ray structural analysis, features of changes in characteristics of crystallographic texture during cold working of Zr-2.5%Nb alloy plates by longitudinal and cross rolling has been investigated. To make original plates, longitudinal fragments and rings of Æ15.0´1.5 mm² tube annealed at 580 °C were used. The plates were rolled at room temperature to the degrees in the range from 6 to 56% with 5…7% per pass and the rate of 5...10s-1. Using the method of inverse pole figures with measuring by the Bragg-Brentano optical scheme, densities of reflections along normal to plane of the plates (pole densities) was determined. Based on this, distributions of orientations of c-axes of hcp lattice of the material have been analyzed. Local features of the distributions, which were attributed to signs of twinning effects in texture changes in the alloy, are revealed. At subsequent analysis, an effect of strain non-uniformity associated with prehistory of the plates was taken into account. It is established that the second stage of (moderate) changes in Kearns textural coefficient of the plates with the deformation degrees differs from the initial stage of accelerated changes by activation of compression twins. By the method of tilt scanning (of rocking curves) around the Bragg-Brentano position at registration of (0004) reflection intensities, changes in orientation distributions of c-axes in longitudinal and cross section of the plates for both parties were investigated. It is noted that the main textural changes in process of deformation of the plates occur in the cross-sectional plane of the original tube and are most expressed on the cross-rolling plates. The doublet in the distributions of c‑axes, characteristic for rolling texture of hcp metals of titanium subgroup, was noted just at the second stage of the texture changes in the material. Its directionality is mainly associated with the plane of cross-section of the original tube. A connection is revealed between features of the pole density distributions and expression degree of the textural doublet on the rocking curves. According to the results obtained and analysis of other publications, twinning nature of the textural doublet was confirmed and a schematic sequence of its formation was proposed with participation of compression twins of{112-2}{1-1-23} system and tensile twins of {101-2}{1-011} and{112-1}{1-1-26} systems.

Texture Formation Behaviour during High-Temperature Plane Strain Compression Deformation in AZ91 Magnesium Alloy

In previous study, it was investigated texture formation behaviour of high-temperature plane strain compression test at 723K, under a strain rate of 5.0. It was found that the main texture component and it was sharpness vary depending on deformation conditions. To clarify the characteristic of texture formation behaviour, it is necessary to investigate at various deformation condition. Therefore, in this study, is investigating the influence or texture formation behaviour and strain, strain rate at 673K. Three kinds of specimens with different initial textures were machined out from a rolled plate having a <0001> texture. The plane strain compression tests were conducted at a temperature 673K, and a strain rate of 5.0, with strain between-0.4 to-1.0. After compression tests, the specimens were immediately quenched in oil. The texture evolution was conducted by the Schulz reflection method using Cu Kα radiation and EBSD. Before the deformation, {0001} of specimen A was accumulated in the center of pole figure. The {0001} of specimen B was accumulated at the RD direction. The {0001} of specimen C was accumulated TD direction. As a result, work softening is observed in all the cases at the true stress – true strain curve for three types of specimens. After deformation, the maximum pole density of increases with increasing strain. In this study, it was found that the stable orientation was (0001)<100> and (0001)<110> during deformation.