Relationship between acoustic emission and microcrack formation in single crystals of Hadfield steel

Abrasive wear is not favorable for Hadfield steel. The connection between the acoustic emission signal and th

Effect of multistage high temperature thermomechanical treatment on the microstructure and mechanical properties of austenitic reactor steel

The deformation microstructures formed by novel multistage high-temperature thermomechanical treatment (HTMT) and their effect on the mechanical properties of austenitic reactor steel are investigated. It is shown that HTMT with plastic deformation at the temperature decreasing in each stage (1100, 900, and 600 C with a total strain degree of e = 2) is an effective method for refining the grain structure and increasing the strength of the reactor steel. The structural features of grains, grain boundaries and defective substructure of the steel are studied in two sections (in planes perpendicular to the transverse direction and perpendicular to the normal direction) by Scanning Electron Microscopy with Electron Back-Scatter Diffraction (SEM EBSD) and Transmission Electron Microscopy (TEM). After the multistage HTMT, a fragmented structure is formed with grains elongated along the rolling direction and flattened in the rolling plane. The average grain size decreases from 19.3 m (for the state after solution treatment) to 1.8 m. A high density of low-angle boundaries (up to 80%) is found inside deformed grains. An additional cold deformation (e = 0.3) after the multistage HTMT promotes mechanical twinning within fragmented grains and subgrains. The resulting structural states provide high strength properties of steel: the yield strength increases up to 910 MPa (at 20 C) and up to 580 MPa (at 650 C), which is 4.6 and 6.1 times higher than that in the state after solution treatment (ST), respectively. The formation of deformed substructure and the influence of dynamic strain aging at an elevated tensile temperature on the mechanical properties of the steel are discussed. Based on the results obtained, the multistage HTMT used in this study can be applied for increasing the strength of austenitic steels

Fabrication of promising Cu-Al-Ni alloys by electron-beam additive manufacturing

The samples of the promising Cu-Al-Ni alloys were fabricated by electron-beam additive printing and studied by electron microscopy. The fabrication was carried out using the combined powder feed and wire feed technology. The samples obtained by specific selecting the printing regime, varying the degree and mode of post-processing, were characterized by homogeneous chemical composition structure. The microstructure and elements distribution of the obtained material was determined by scanning electron microscopy. In the case of printing without additional electronbeam treatment, an irregularity of the microstructure, chemical composition, precipitation of intermetallic phases was observed

Characteristic features of physical and mechanical properties of ultrafine-grained Al–Mg alloy 1560

Specimens of Al–Mg alloy 1560 of ultrafine-grained structure were obtained by the method of severe plastic deformation based on multiple equal-channel angular pressing. Impact on physical and mechanical properties of the processed material and fracture pattern of specimens was studied. Tensile tests showed an increase of the offset yield strength and resistance to rupture with decrease in the ultimate deformation. The obtained specimens have increased microhardness values compared to the initial ones. It was established that the last cycle of pressing determines the structural orientation of macroscopic shear bands occurring at an angle to the specimen longitudinal axis while passing connection of channels. It affects the physical and mechanical properties of the material and fracture pattern. The quality control of the obtained specimens by the method of ultrasonic defectoscopy and X-ray tomography confirmed the absence of macroand microdefects when following the matched optimal regime of processing

Impact of dispersion hardening by alumina nano particles on mechanical properties of Al 1100

The paper presents a study on the effect of adding a small amount of particles to a technically pure aluminum alloy on its structure and mechanical properties. For this purpose laboratory castings of Al 1100 alloy with the addition of 0.5 and 1.0 wt% Al2O3 were produced. The introduction of master alloys containing particles into the melt was accompanied by ultrasonic treatment. Images of the structure of the alloys obtained showed that ultrasonic treatment contributes to producing a material with zero porosity; this fact is also confirmed by the measurement of density which values are close to the theoretical ones. Analysis of mechanical properties revealed that the conditional yield strength, tensile strength and hardness of the nanocomposite with a metal matrix Al 1100/wt. nano Al2O3 were prone to increase with increasing the percentage of aluminum oxide in the matrix alloy while reducing the plasticity. This behavior of studied alloys reinforced with nanoparticles is a consequence of refining the grain structure of the material during crystallization due to the presence of particles acting as inoculants

Microstructure of Vein Quartz Aggregates as an Indicator of Their Deformation History: An Example of Vein Systems from Western Transbaikalia (Russia)

We investigated the microstructural and crystallographic features of quartz from complex vein systems associated with the development of thrust and shear deformations in Western Transbaikalia using electron back scatter diffraction (EBSD) and optical microscopy. Vein quartz systems were studied to obtain insights on the mechanisms and localization of strains in quartz, in plastic and semibrittle conditions close to the brittle–ductile transition, and their relationship to the processes of regional deformations. Five types of microstructures of vein quartz were distinguished. We established that the preferred mechanisms of deformation of the studied quartz were dislocation glide and creep at average deformation rates and temperatures of 300–400 °C with subsequent heating and dynamic and static recrystallization. The formation of special boundaries of the Dauphiné twinning type and multiple boundaries with angles of misorientation of 30° and 90° were noted. The distribution of the selected types in the differently oriented veins was analyzed. The presence of three generations of vein quartz was established. Microstructural and crystallographic features of vein quartz aggregates allow us to mark the territory’s multi-stage development (with the formation of syntectonic and post-deformation quartz)

Relationship between acoustic emission and microcrack formation in single crystals of Hadfield steel

Abrasive wear is not favorable for Hadfield steel. The connection between the acoustic emission signal and th

Characteristic features of physical and mechanical properties of ultrafine-grained Al–Mg alloy 1560

Specimens of Al–Mg alloy 1560 of ultrafine-grained structure were obtained by the method of severe plastic deformation based on multiple equal-channel angular pressing. Impact on physical and mechanical properties of the processed material and fracture pattern of specimens was studied. Tensile tests showed an increase of the offset yield strength and resistance to rupture with decrease in the ultimate deformation. The obtained specimens have increased microhardness values compared to the initial ones. It was established that the last cycle of pressing determines the structural orientation of macroscopic shear bands occurring at an angle to the specimen longitudinal axis while passing connection of channels. It affects the physical and mechanical properties of the material and fracture pattern. The quality control of the obtained specimens by the method of ultrasonic defectoscopy and X-ray tomography confirmed the absence of macroand microdefects when following the matched optimal regime of processing