Abstract
The questions about metrological assurance and evaluation of the reliability of decision-making on the state of a metal control object during eddy current testing of surfaces with complex structure are considered in this article. The target of the research is the complex surfaces from position of their geometry and electromagnetic characteristics, that are formed on the surface of metal products during the formation of welded joints.During the quality control of state of welded joints, first of all, the special attention is given to the identification of internal and external defects of the joint weld. However, the quality of the joint weld, from position of its mechanical characteristics, is no less affected by the shape, size and composition of the joint weld. The task of controlling the size and shape of the joint weld is quite successfully solved by applying the visual-optical method of nondestructive control. With regard to composition of the joint weld, the eddy current method of control allows to determine the composition of the material of the welded joint by measuring the magnetic and electrical characteristics of the metal.The use of eddy current method of control allows to determine the geometrical parameters of a metal object and its electromagnetic characteristics. However, in this case, the uncertainty appears that is associated with the impossibility of determining which of the factors (the geometric dimensions of the object of control or the change in its electromagnetic characteristics), to some extent, has affected the measurement result of the signal of the eddy current transducer.This article analyzes the influence of these factors from the point of view of their metrological characteristics and provides the formulas that allow to estimate the risks of the customer and the executor in the case of control of complex surfaces by the eddy current method.
Highlights
In the practical application of the eddy current method of quality control of electrically conductive objects with a complex surface structure, as a result of measuring informative parameters, the decision on validity or non-validity of the control object (OС) is made depending on whether the monitored parameter is within the permissible li mits [1]
The limited measurement accuracy of the output signals of the eddy current transducer (ECT) and the impossibility of providing ideal conditions for testing often leads to erroneous decisions, i. e. to the recognition of the object fit for operation as unfit and vice versa
The decision is made by the operator, who in the process of control compares the signal of the eddy current transducer with a set of reference signals, i. e. signals from a weld with known geometric and mechanical characteristics [1]
Summary
In the practical application of the eddy current method of quality control of electrically conductive objects with a complex surface structure, as a result of measuring informative parameters (amplitudes and phases of the output signal of the eddy current transducer), the decision on validity or non-validity of the control object (OС) is made depending on whether the monitored parameter is within the permissible li mits [1]. Typical examples of such surfaces are welded joints, to which technical requirements are established regarding the dimensions of the weld bead and its surface roughness. The objective of this work is to obtain dependencies for calculating the reliability of control of welded joints, taking into account the metrological characte ristics of the instruments and the characteristics of the welded joint
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