Ferromagnetic Metal Property Measurement via Eddy Current and Magnetic Field Sensors
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Solution Overview
Problem
Existing methods for determining mechanical-technological characteristic variables of ferromagnetic metals, particularly in pipelines, face challenges due to interference from remanent magnetization, defects, and other sources, making it difficult to achieve accurate measurements.
Innovation Solution
A method utilizing an eddy current sensor to measure the electrical conductivity or specific electrical resistance of ferromagnetic metals by generating an eddy current in substantially saturated metal, with a magnetic field strength sensor to minimize interference, and deriving mechanical-technological properties like tensile strength and hardness from these measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromagnetic methods are used to determine mechanical-technological characteristic variables, then measurement capability is provided, but measurement accuracy deteriorates due to interference from remanent magnetization and defects
Solution Approach 1:
The patent extracts and eliminates the harmful influence of remanent magnetization by using alternating magnetization directions that cancel out residual magnetic effects. The measurement method separates the useful eddy current signal from the interfering remanent magnetization through differential measurement techniques, effectively removing the harmful factor while preserving the measurement capability.
Solution Approach 2:
The patent changes the magnetization parameters by using alternating magnetization directions and varying the amplitude and frequency of the magnetizing field. By controlling the magnetization parameters and using differential measurements at different conditions, the method achieves accurate determination of mechanical properties while compensating for interference from defects and remanent magnetization.
2Reliability
If hysteresis curve properties are measured, then material characterization is achieved, but measurement reliability deteriorates in pipelines with multiple interference sources
Solution Approach 1:
The patent converts the harmful effect of remanent magnetization into a useful measurement parameter. By measuring the changes in hysteresis loop area and shape under alternating magnetization, the method actually uses the remanent magnetization effects to derive information about material properties while compensating for their interfering influence through differential measurement techniques.
Solution Approach 2:
The patent employs periodic alternating magnetization with different amplitudes and frequencies to distinguish between permanent interference sources (defects, remanent magnetization) and the actual material properties. The periodic variation allows separation of static interference from dynamic material response, significantly improving measurement reliability in complex pipeline environments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides accurate determination of mechanical-technological properties with a high correlation coefficient, minimizing interference and ensuring reliable measurements even in complex pipeline environments.
Implementation Method 1
a sensor apparatus comprising a transmission coil generates an, in particular varying, magnet field which interacts with the magnetic field which is generated by the magnetization apparatus in the metal, and which leads to an eddy current being formed
Implementation Method 2
The eddy current is therefore generated by the transmission coil in the metal which is magnetized by the magnetization apparatus
Implementation Method 3
a magnetization apparatus, which has at least one permanent magnet or solenoid, magnetizes the material which is to be determined
Data Source
AI summary
A method is disclosed for determining a mechanical-technological characteristic variable of ferromagnetic metals, preferably ferromagnetic steels, and in particular fine-grained steels, which are used in pipelines. A magnetization apparatus, which has at least one permanent magnet or solenoid, magnetizes the metal which is to be determined, and a sensor apparatus comprising a transmission coil generates a magnetic field which interacts with the magnetic field which is generated by the magnetization apparatus in the metal, and which generates an eddy current. The eddy current is generated in the magnetically at least substantially saturated metal, and the eddy current is measured by an eddy current sensor of the sensor apparatus. A magnetic field strength sensor measures the magnetic field of the metal at least close to the surface, and the electrical conductivity or the specific electrical resistance of the metal is ascertained from the data from the eddy current sensor on the basis of reference data by means of an evaluation apparatus. The characteristic variable of the metal is derived from the conductivity or the resistance, and also an inspection gauge for carrying out a method of this kind.