Solid State Phenomena Vol. 328

Abstract: The paper reports changes in strain fields on welded sample surfaces from commercial pure titanium, joined by both laser beam welding (LBW) and gas tungsten arc welding (GTAW) procedures, under uniaxial tensile loads. Their dynamics were investigated by the digital image correlation method using a ‘Vic-3D’ optical system. In addition, stress-strain curves were drawn in both σ_eng-ε_eng and σ_true-ε_true coordinates. It was shown that the laser welded sample was characterized by a higher ultimate tensile strength to yield point ratio than the as-received one. The GTAW sample fractured under much less stresses than the LBW one.

Abstract: A review of publications on metallurgical and foundry production showed that many authors, when analyzing the properties of liquid metals and alloys, proceed from the concept of their cluster structure. The cluster structure of a liquid is a hypothesis, but it is confirmed by studies of diffraction of X-rays, electrons and neutrons reflected from its surface. This paper considers the existing concept that a cluster is a crystal-like concentration of atoms. Around the clusters there is a weakened zone, which consists of disordered atoms, the volume of which does not exceed 3 ... 5%, and this provides the fluidity of many melts. The authors of the publications have achieved success in explaining the forming structure of ingots, proceeding from the cluster mechanism of the crystallization of liquid metals and alloys. The authors of this work suggested that the superheated liquid metal in the head of the bath, which has smaller clusters, moves under the action of magnetic fields to its tail, and provides refinement of the weld metal structure during welding with the action of a control transverse magnetic field.

Abstract: Thermochromic properties were found in bimetallic hybrid inorganic-organic complex compounds of hexa (thiocyanate-N) chromates (III) of IIIb-group rare-earth metals and lanthanides complexes with dimethylsulfoxide [M(C₂H₆SO)₈]L, dimethylformamide [M (C₃H₇NO)₈]L, ε-caprolactam [M(εC₆H₁₁NO)₈]L and nicotinic acid [M(C₅H₅NCOO)₃(H₂O)₂]L·nH₂O, n=1,2, L=[Cr (NCS)₆]^3-, M=Sc³⁺, Y³⁺, Ln³⁺, obtained by means of direct synthesis from the aqueous solutions, the composition of substances was studied by methods of chemical and electron microscopic analyzes, solubility and chemical resistance were determined. Radiographic and thermogravimetric characteristics, IR spectra, magnetic properties are studied. The experimental data obtained indicate the antiferromagnetic nature of the interaction between paramagnetic centers in the studied ionic compounds, the crystallographic parameters of which were determined by the method of X-ray diffraction analysis of single crystals at low temperatures. In the temperature range of 383-493 K, substances, without changing the physicochemical characteristics, reversibly change color, withstanding many heating-cooling cycles.

Abstract: Modeling of the temperature distribution during electric arc surfacing with a strip electrode is carried out in relation to the design scheme of a semi-infinite body. Also, in the work, the temperature distribution was calculated when a flat layer was heated by a linear source, which made it possible to compare the temperature distribution data without and taking into account the heat release conditions at the product boundaries. The simulation results showed that the control of heat input into the base metal when using mechanical control actions makes it possible to reduce the overheating of the weld pool, reduce the area of the melting isotherm, and reduce the cooling rate of the heat-affected zone. By calculation, the previously determined optimal range of values of the frequency of control actions of 40÷60 Hz was confirmed, which makes it possible to ensure the minimum depth of penetration of the base metal and obtain a favorable structure in the heat-affected zone, prone to the formation of a coarse-grained structure.

Abstract: The work investigated the effect of thermal limiters on the distribution of heat in the product and the formation of the structure of multilayer samples made of stainless steel AISI 308LSi deposited by electric arc welding in argon. It was found that as a result of the formation of products using thermal limiters, the high temperature regions deepen towards the substrate. It was revealed that the greatest effect of thermal limiters is observed in the central parts of the products. An increase in the fraction of γ-Fe is observed, which is confirmed by the dissolution of the dendritic axes of δ-Fe, in the sample obtained using thermal limiters. The obtained results confirm the prospects for producing multilayer products with increased mechanical properties by the method of electric arc welding using thermal limiters.

Abstract: The paper investigates the influence of the forming graphite skids on the change in the hardness of multilayer samples made of stainless steel AISI 308LSi deposited by electric arc welding in argon. Utilization of graphite skids makes it possible to obtain a product with a smoother outer side surface. An increase in the fraction of the austenite phase is observed in the samples obtained using graphite skids. An increase in the proportion of the austenite phase leads to an overall increase in the hardness of the product.

Abstract: The heat-induced behavior of strength characteristics demonstrated by a “steel – wood” composite has been studied. The study has revealed the bending strength of steel plates in contact with a wooden bar is maximal if treated by a flame retardant agent containing phosphorous and urea solution.