The paper presents the results of a study on the microstructure and mechanical properties of a mediumcarbon steel (0.45 % C) processed by severe plastic deformation (SPD) via high-pressure torsion (HPT). Martensite quenching was first applied to the material, and then HPT processing was conducted at a temperature of 350°C. As a result, a nanocomposite type microstructure is formed: an ultrafine-grained (UFG) ferrite matrix with fine cementite particles located predominantly at the boundaries of ferrite grains. The processed steel is characterized by a high-strength state, with an ultimate tensile strength over 2500 MPa. Special attention is given to analysis of the thermal stability of the microstructure and properties of the steel after HPT processing in comparison with quenching. It is shown that the thermal stability of the UFG structure produced by HPT is visibly higher than that of quenchinginduced martensite. The origin of the enhanced strength and thermal stability of the UFG steel is discussed.
The quality of coating on the high-silicon aluminum alloy Al-12%Si depending on the initial microstructure of the samples has been investigated. The method of microarc oxidation (MAO) has been used for coating. The quality of coating was evaluated by the thickness and microhardness of the formed layer. The initial microstructure of aluminum alloy samples was varied by distribution of silicon particles in the volume of the matrix solution. The possibility of obtaining a high-hardness protective coating on the alloy Al-12%Si by the MAO method has been shown. The influence of the alloy microstructure on the microhardness and thickness of coatings has been established. It has been shown that the deformation thermal treatment of Al-12%Si alloy samples before MAO leads to deterioration in the quality of the formed layer. A model of the influence of the silicon particles distribution on the quality of the micro-layer has been represented for explanation of the observed effect. The increase of microhardness in coatings with a greater thickness has been revealed.
This investigation is on the properties of hardened layers, developed with the micro-arc oxidation method (MAO) on the surface of the ingots from an Al-Si alloy. It has been established that the properties (microhardness, thickness, porosity) of the generated surfaces depend on the structure of the alloy.
___________________________________________________________________________________________
AbstractThe microstructure and microhardness of joint welds formed with linear friction welding (LFW) of an Al-Cu-Mg alloy was investigated. Welds of two samples of rectangular shape do not show any macroscopic defects and are characterized by high strength. The substantial transformation of the microstructure occurs in the weld. The lattice parameter decreases in the weld centre compared to the base material.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.