Study of the dynamic hardness of structural metal materials

The mechanical properties of structural metallic materials are the most important indicators of their quality. Different methods (i.e., the methods of Shore, Brinell, Rockwell, Leeb, Vickers, method of instrumental indentation, and others) are currently used for determination of the hardness — one of the most important mechanical characteristics of structural metal materials. Among them is the method of dynamic indentation first developed at the Institute of Applied Physics of the National Academy of Sciences of Belarus. With the goal of further developing of the method of dynamic indentation, we propose the procedures aimed at increasing the accuracy of assessing the hardness of structural metallic materials: parameters of the contact interaction of the indenter with the sample material (Brinell hardness values) were measured using a dynamic indentation (DI) device; the values of surface and volumetric dynamic hardness were calculated taking into account the characteristics obtained using a DI device; a comparative analysis of hardness estimates obtained by different approaches was carried out. As a result of the comparative analysis of the methods, as well as their experimental testing, it was shown that an increase in the accuracy of hardness assessment can be achieved by using the «energy» approach based on assessing the ratio of the total work to the volume of the recovered indentation upon dynamic indentation of structural metal materials. The use of the «energy» approach provided obtaining the sample standard deviation of the volumetric dynamic hardness values, which, in turn, was significantly lower than the sample standard deviation of the surface dynamic hardness values and data of the dynamic indentation device, which directly affects an increase in the accuracy of hardness estimation during dynamic indentation of structural metal materials. Proceeding from the «energy» approach, a new algorithm for processing the initial signal is proposed when the dynamic hardness is determined using a dynamic indentation device.

Extractive Metallurgy of Aluminum

Aluminum comprises 8% of the earth’s crust and is the most abundant structural metal. Its production has surpassed that of copper and approaches that of iron. This article is a review of all aspects of the production of aluminum including: the raw materials from which it derived, production of aluminum from bauxite, electrolytic reduction of aluminum oxide, purification and refining, and environmental aspects of production processes.

Development of Structural Metal Energy-Dissipation Techniques for Seismic Disaster Mitigation of Buildings in China

Buildings in seismic zones are required to provide proper stiffness and load-bearing capacity to resist frequent earthquakes, and possess proper ductility and energy-dissipating capacity to prevent collapse under rare earthquakes. To meet these requirements, the concept of structural energy-dissipation techniques for the bi-functions of load-bearing and energy dissipating are proposed. A number of structural metal energy-dissipation elements, such as buckling-restrained steel plate shear walls, non-buckling corrugated steel plate shear walls, two-level yielding steel coupling beams and energy-dissipative columns, have been developed. They are designed to provide stiffness/strength to guarantee the operation of buildings under frequent earthquakes, but also dissipate energy to reduce seismic effects to a considerable extent for collapse-prevention of buildings. The experimental and theoretical studies on these structural metal energy-dissipating dampers are presented. The efficiency of these structural dampers for disaster mitigation of buildings against earthquakes are also presented to provide a reference for their practical application.

Fluorescent zinc(ii)-based metal–organic frameworks for nitroaromatics sensing

A new structural metal–organic framework with fluorescence properties was synthesized and applied for sensitive and selective sensing of nitroaromatics.