Papers by Keyword: Substructure

Abstract: Phase components of experimental low cost titanium alloys, their substructure and parameters, dislocation structure, features of phase formation in the metal, which differ in alloying systems, were studied using complex research methods. The stoichiometric composition of dispersed phases in the internal volumes of alloy grains was determined by diffraction patterns using transmission electron microscopy. It is shown that in the structure of titanium alloy Ti-2,8Al-5,1Mo-4,9Fe there are dispersed nanoparticles of intermetallic phases of different morphology and stoichiometric composition. These are the phases: Ti₃Al and Fe₂Ti with a size of 10…40 nm; Mo₉Ti₄ - 20…120 nm. Studies of titanium alloy Ti-1,5Fe-O showed the presence in the structure of mainly nanoparticles of oxides: Ti₃O₅ size 10…30 nm and Ti₄Fe₂O, FeTiO₅ (10…90 nm), as well as intermetallics Fe₂Ti (10…40 nm). It is established that the formation of nanoparticles of intermetallic and oxide phases in the thin plate structure of the investigated experimental low cost titanium alloys promotes the formation of the substructure with uniform distribution of dislocation density. This provides a high level of mechanical properties of alloys.

Abstract: The essential task of modern industry is to increase the reliability and durability of products. One of the promising ways to increase the products operational durability is the ceramics and cermets powders functional coatings application to the working surfaces by the method of high-speed multi-chamber detonation spraying. The objective of the given paper is to determine the regularities of the influence of structural-phase features in the formed material of functional cermets coatings of metal parts on their strength characteristics and crack resistance, while taking into account structural criteria that will provide the required set of strength and crack resistance properties. The method for deep and detailed analysis of the structure features, morphology and distribution of phase particles, their stoichiometric composition, substructure parameters, dislocation density in the coating material obtained due to multi-chamber detonation spraying has been developed in this paper. The research of detonation coating material was carried out using transmission electron microscopy (TEM) on JEM-200CX instrument (produced by JEOL company) with the accelerating voltage of up to 200 kV. The prospects of using the method of multi-chamber detonation spraying on various materials (steel, copper, aluminum, titanium) and alloys are shown on the basis of the research results. A number of composite coatings made of aluminum and zirconium ceramics; chromium, tungsten carbides have been obtained. It has been defined that changes occur in the ratio of the following parameters: microhardness, pore volume fraction, phase composition, distribution of dispersed phases, grain, subgrain, dislocation structures, etc, under different processing modes in the surface layers and corresponding change in the modes of detonation spraying.

Abstract: The effect of Pb small additives on the microstructure and phase composition of palladium-based diffusion membrane-filters was studied in this work. In the present study, we comprehensively investigated the lead-containing palladium alloy by X-ray diffraction using synchrotron radiation and high-resolution scanning electron microscopy. The predisposition of the alloy to the formation of a conditionally homogeneous nanodisperse substructure with small values of micro-deformations is established. The stable preservation of the phase composition during a single hydrogenation is revealed.

Abstract: The influence of thermal cycling treatment of pseudo-α-titanium alloys OT4 and VT20 on their structural and substructural characteristics, as well as their mechanical properties is considered. A significant change in structural characteristics is established. This contributes to an increase in the strength properties of alloys with satisfactory ductility and high-temperature strength.

Abstract: Derrick and substructure is one of rig’s core equipment components, and it is also the most important weight component of rig. The working environment of derrick and substructure is very serious, whose material should has high strength, excellent plasticity, toughness and weldability property. In this paper, the chemical composition, micro-structure, tensile property, impact property, hardness and weldability of high strength pipeline steel with strength grades of X70 (485MPa)~ X100(690MPa) were systematically analyzed. The analysis and study of the service environment of rig derrick and substructure as well as the technical requirements of the material, showed that the performance of high strength pipeline steel was obviously better than that of the same grade high strength low alloy structural steel used in rig derrick and substructure at present, and it can fully meet the technical requirement of rig derrick and substructure. The application of high strength pipeline steel to rig derrick and substructure will improve the service property, optimize the design , and fully ensure the service safety of rig derrick and substructure.

Abstract: Under industrial conditions, it is common to avoid undesirable costly modernization of the existing equipment and increase the production efficiency. That is why as a basis of the solution to the scientific-applied problem, the authors took the idea of the adjustment of temperature-deformation regimes of metal-roll thick plate rolling for building constructions of the certain assignment in the way to initiate heterogeneous origination of ferrite on the polygonal boundaries of austenite as well as to form, before the finish rolling, as much as possible dispersed grain of hypoeutectoid ferrite. It must guarantee the formation of highly-dispersed final ferrite-perlite structure and the high level of strength and plasticity of the thick plate.

Abstract: The UNS S32205 duplex stainless steel was warm rolled at 600°C with 60 and 80% of thickness reduction. The microstructure was characterized by optical, scanning and transmission electron microscopy, X-ray diffractometry and EBSD. The corrosion resistance was evaluated by electrochemical behavior in the chlorine ion environment using potentiodynamic polarization measurements. The tensile strength reached 1185 MPa and 1328 MPa, after warm rolling with 60 and 80%, respectively. In steel as-supplied, hot rolled and annealed, the tensile strength was 774 MPa. Ferrite microtexture presented the α-fiber and the rotated cube component, while the austenite enhanced the brass, copper, and cube components to a lesser extent. The substructure was characterized by intense formation of tangles and forests of dislocations and discrete subgrains in the ferritic phase and by planar gliding of dislocations and formation of dense dislocations walls in the austenite. Despite the existence of a certain similarity among the values of pitting potentials obtained for all samples, the number of pits observed was higher in the as-received sample, followed by the samples with 60 and 80% reduction. These results draw attention to innovative routes in the industrial production of duplex stainless steel of this class, even considering ductility lost. Keywords: Warm rolling; Mechanical strength; Texture; Substructure; Corrosion resistance

Abstract: NiTi shape memory alloy (SMA) vascular stent, with good bio-compatibility and super-elastic properties, has become an important medical device in clinical treatment of cardiovascular or cerebrovascular diseases. The free expansion of stent in vessel involves the mechanical behavior of geometric large deformation related to the structure of super-elastic. In this paper, the nonlinear mechanical model for the substructure of NiTi shape memory alloy vascular stent is established, and the displacement deformation equation is derived. The geometric non-linearity of the structure is proved. Furthermore, the geometric nonlinear mechanical model is verified by numerical method. The mechanical analysis model of NiTi shape memory alloy vascular stent is widely used in the field of tracheal stent and so on.

Abstract: A Fe-3wt% Si strip was produced using a vertical type twin-roll casting process. Sub-grains with an inhomogeneous distribution through the thickness direction were firstly observed in the as-cast strip. It was found that the surface layer was characterized by columnar grains containing lineage sub-grains, the subsurface layer was dominated by numerous polygonal sub-grains inside columnar grains or fine equiaxed grains, and the center layer was composed of coarse equiaxed grains without sub-grains. In addition, the sub-grain boundaries provided additional nucleation sites for precipitates and the nanoscale MnS particles were successfully obtained. Moreover, the average size of MnS precipitates in the surface layer was smaller than that in the subsurface layer. The inhomogeneous distributions of sub-grains and precipitates can be attributed to the large temperature gradient through the thickness direction during the strip casting process.

Abstract: During the oil drilling process, the eccentric rotation of rotating devices such as rotary table may excite abnormal vibration of the drilling rig which will worsen the working condition of the rig and cause structure failure. In this paper, a ZJ70 drilling rig is taken as the study object, the harmonic response analysis of which is conducted by using FEM software and the frequency response characteristic of the substructure is obtained. Result shows the stiffness of rear substructure is insufficient. On the basis of harmonic response analysis, the modification of the substructure is carried out through enlarging the rear connection frame. Further calculation shows the first 3 order natural frequencies of the substructure are increased, thus the abnormal vibration of the substructure caused by the rotary table with certain rotation speed can be effectively reduced. In addition, the displacement response of both first two orders are greatly decreased with that of central and rear positions are respectively decreased by 17.5% and 42.1%, which demonstrates the dynamic characteristic of the substructure is significantly improved.