Abstract
The article is devoted to the analysis of elastic and plastic characteristics of composite materials during hot stamping. The purpose of this work is to offer optimal conditions for hot plasticity of composite porous material with determination of temperature conditions of hot stamping excluding the appearance of defects in the structure. Production of details of the difficult form by method of hot stamping from preparations of the cylindrical form is followed by development of barrel on a peripheral surface. Sludge sintered porous blanks, and sediment compact material, accompanied by a nonuniform height lateral deformation. In connection with the action of friction forces on the contact surfaces, this leads to the formation of a “barrel”. The heterogeneity of the deformed state is associated with the appearance of tangential tensile stresses on the free surface of the workpiece. If they exceed some critical degree of transverse deformation, cracks appear on the side surface, which leads to gas saturation (oxidation) of the inner layers of the forging, to the ingress of grease into them and its pressing into the volume of the part during hot stamping. In the end, this significantly reduces the properties of hot-stamped parts. Conclusion: the methods of determining the elastic characteristics depending on the geometric parameters of the workpieces, the applied strain energy, body density and temperature dependence of the plasticity characteristics of the hot deformation of the powder material are сonsidered.
Highlights
The problem of non-destructive testing of structural materials in actual condition is very relevant, because defects and changes in the structure of the material arising in the manufacture and operation of products can significantly reduce their strength
The values of the elastic modulus and Poisson's ratio of even pure substances-elements and chemical compounds of constant composition, determined on materials of different purity by different methods − are very different, which indicates their lack of reliability
Some of them are devoted to theoretical methods for determining the elastic modulus and Poisson's ratio [1], and some − experimental [2,3]
Summary
The experimental values of the mean density of the deposited samples are shown in table 1., which are observed on the Astaloy 0.85 Mo microstructure (Fig. 1). Ρs, ρ0 - density of quartz sensor and sample; ls, l0 - quartz sensor and sample lengths; ∆fx, ∆fy - average frequency differences between neighboring harmonics. The maximum relative error in determining the young's modulus in the applied opticalacoustic method is δE = 6%. The maximum relative error in determining the Jung's modulus in the applied opticalacoustic method is δE = 6%, the shear modulus - δG = 4%, the Poisson's ratio - δμ = 5%. As a test sample with known values of elastic modules, an aluminum sample (density ρ = 2,69 ∙ 103 kg⁄m3, thickness H = 7,3 mm) was studied.
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