Complex method for checking physicomechanical characteristics of materials of metalworks
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COMPLEX METHOD FOR CHECKING PHYSICOMECHANICAL CHARACTERISTICS OF MATERIALS OF METALWORKS O. M. Karpash,1 E. R. Dotsenko,1, 2 and M. O. Karpash1
UDC 620.179
We present some results of laboratory tests of an information-and-measuring system intended for determining the physicomechanical characteristics of ferrite-perlitic constructional steels. We have developed a mathematical model for checking the electric resistivity of plane specimens by the electrocontact four-point probe technique. We also describe a method for determining the yield strength of steels by the values of their electric resistivity and hardness with the use of algorithms of artificial neural networks. Keywords: physicomechanical characteristics, yield strength, electric resistivity, constructional steels, four-point probe technique, neural networks.
The problem of ensuring the reliable and safe use of metalworks becomes more and more urgent because their wear exceeds substantially the rates of technical re-equipment. The materials of metalworks during their operation are subjected to damages, whose nature depends on the kind of loading and conditions of work (cyclic loads, high and low temperatures, corrosive environment, etc.). The combined action of these factors leads to changes in the microstructure and physicomechanical characteristics (PMC) of the material of metalworks [1]. In addition, engineering practice shows that a significant amount of equipment whose service forms and records have been lost is in use now. This fact also requires regular checking the actual physicomechanical characteristics of materials for finding the deviations of their values from standard ones. Domestic and foreign scientists work actively on the development of new methods and means for determining PMC [2–9]. Much attention is given now to complex approaches to the estimation of PMC of steels with regard for several informative parameters. The methods taking into account the informative parameters that concern different types of physical fields (magnetic, electric, thermal, etc.) attract especial interest [10]. The development of new methods of multiparameter testing requires one to solve two main problems: the optimal collection of testing parameters and the development of the corresponding measuring instruments (or choice of existing equipment). In particular, for determining PMC, it was proposed to use structurally sensitive informative parameters. Taking into account the above-stated and results of theoretical investigations [11, 12], we developed a complex method of checking PMC according to several parameters: hardness, thermal conductivity, and electric resistivity, whose values are regulated in certificates and normative documents for steel [13]. This method is connected with measuring standard physical characteristics, whose values will be used for the calculation of yield and ultimate strengths. In the first stage, the practical implementation of this approach was realized in the form of an informationand-measuring system FMKh-1, with the help of which w
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