Technology of Forged Steel Eddy Current Roll Surface Detection

In modern industrial manufacturing, eddy current testing technology has become an important tool for ensuring the surface quality of forged steel rolls. Eddy current roll surface detection is based on the principle of electromagnetic induction. Without contacting the workpiece, defects on the roll surface can be identified by detecting changes in the induced current. This article will delve into the application of eddy current testing technology in the surface inspection of forged steel rolls and analyze its significance in actual production.

Advantages and Applications of Eddy Current Roll Surface Detection

Eddy current roll surface detection technology has many significant advantages. Firstly, it does not require direct contact with the workpiece being inspected, avoiding any potential physical damage or surface contamination. Secondly, eddy current testing does not require the use of coupling media, making the operation simple and the detection speed fast. For forged steel cold rolls, eddy current testing typically uses a probe coil for comparative detection, i.e., comparing eddy current signals from different parts of the same workpiece. As the geometrical parameters of the workpiece change minimally, the impact on the coil's impedance is also minor, allowing eddy current testing to accurately detect surface cracks and defects, ensuring the high quality of forged steel rolls.

Another key advantage of eddy current roll surface detection is its ease of online implementation. This not only benefits quality traceability and process control but also enables immediate detection and correction of potential quality issues during production, avoiding defects caused by human error. Eddy current roll surface detection technology, with its fast, accurate, and reliable characteristics, has been widely applied in the quality control of forged steel rolls.

Factors Affecting the Results of Eddy Current Roll Surface Detection

When conducting eddy current roll surface detection, residual stress in the material is an important influencing factor. Studies have shown that during the surface quenching process of forged steel rolls, the transformation of the electromagnetic field of the induction coil may result in localized grain size enlargement and increased surface hardness. These changes directly affect the strength and distribution of eddy current signals.

For example, experimental data show that eddy current signals are mainly concentrated in the near-surface region of the roll, and as the roll diameter increases, the eddy current signal decreases rapidly. This indicates a high correlation between the distribution of eddy current signals and the residual stress in the material. Therefore, the eddy current testing machine can not only identify surface defects but also be used to assess residual stress levels in the material, providing important references for optimizing roll production processes.

Applications in Actual Production of Eddy Current Roll Surface Detection

In actual production, eddy current roll surface detection technology has already shown great potential in identifying and controlling the surface quality of forged steel rolls. Researchers have conducted comprehensive analyses using eddy current testing on different specifications of forged steel samples, combined with hardness tests, chemical composition analysis, metallographic inspection, and residual stress tests. Results show that although eddy current signals may weaken during initial usage, this does not affect the normal use of the rolls. In fact, variations in eddy current signals mainly reflect the uneven distribution of residual stress during surface quenching.

It should be noted that there is currently no unified industry standard for the eddy current testing of forged steel cold rolls. Therefore, each rolling line should establish corresponding eddy current testing control standards based on different rolling conditions and the characteristics of on-site testing equipment to ensure the optimal application of eddy current testing technology.