Keyword: «microstructure»

The features of the stress state, physical-mechanical and structural properties of welded joints of structural steels 09G2S and St3sp, made at low climatic temperatures, are studied. Welded samples were obtained by manual arc welding using domestic electrodes UONI-13/MOROZ, HOBEKS-K-54, LB 52TRU. During the research, pulsed arc welding was tested in comparison with the traditional method of direct current welding. When welding in the cold, an increase in the level of tensile residual welding stresses by an average of 40 ... 50% is observed compared with welding at room temperature. Features of the structure and mechanical properties during welding at negative temperatures are revealed.

The purpose of the work is to develop a multicomponent formulation of modifiers for master alloys of 18-karat white gold with the necessary set of technological, physical, mechanical and economic parameters and properties. Work has been carried out on the manufacture of prototypes of multicomponent alloys of 18-karat white gold, the dependences of the chemical composition and microstructure, their influence on the main physical, mechanical, technological and operational properties have been studied. The tasks for further improvement of the composition of master alloys of white gold alloys, their production technology and properties are determined.

A complex of methods was used to study the microstructure, elemental and phase composition of a diamond-containing hard-alloy matrix obtained by impregnation of the Fe-C eutectic melt in vacuum. It was found that the matrix consists of phases of tungsten carbide with a relative content of 61.0%, iron carbide – 17.0%, α-Fe – 16.5%, and graphite – 5.5%. The Fe-C eutectic alloy, which acts as a binding component of the matrix, consists of a ferrite-pearlite metal base with graphite inclusions. The microhardness of the matrix based on tungsten carbide impregnated with Fe-C melt is ~11 GPa, which is more than 3 times higher than the microhardness of the tungsten-cobalt matrix obtained by sintering with copper impregnation

The content of 1,2-links in the butadiene fragment of butadine-nitrile rubbers was calculated, the temperatures of the glass transition of rubbers and rubbers based on them were determined. Using the Pearson correlation, it is shown that the mobility of macromolecules of butadiene-nitrile rubbers is de-termined not only by the content of bound acrylоnitrile, but also by the microstructure of the butadiene link. It was found that with an increase in the content of bound acrylonitrile, the change in glass transition tem-peratures between rubber and rubber based on it decreases as a result of vulcanization.