ABSTRACT

Based on relationships between electromagnetic properties and microstructural changes in steel, the current paper describes the development of an electromagnetic technique to determine steel hardenability, non-destructively. Performing Jominy end-quench test, magnetic hysteresis loop and eddy current methods have been applied to SAE 4140 standard steel samples to explore applicability of the non-destructive techniques for determining hardenability. Different hysteresis loop parameters (maximum magnetic flux density, coercivity, hysteresis loss and maximum differential permeability) as well as eddy current outputs (induced voltage, normalised impedance and phase angle) as a function of distance from the end-quenched surface were investigated and the results show a clear agreement with data obtained by traditional hardness testing. In addition, taking advantage of a generalised regression neural network, magnetic data obtained from hysteresis loop and eddy current methods could be used to accurately estimate results in the hardness profile of a given sample, using a few training data points. This paper shows that coupling the proposed non-destructive methods to Jominy end-quench test facilitates accurate non-destructive hardenability determination of steel samples while reducing time and cost of the test process.

摘要

基于电磁特性与钢的微观结构变化之间的关系，本文描述了电磁技术的发展，以非破坏性地确定钢的淬透性。对 SAE 4140 标准钢样品进行了 Jominy 端淬测试、磁滞回线和涡流方法，以探索非破坏性技术在确定淬透性方面的适用性。研究了不同的磁滞回线参数（最大磁通密度、矫顽力、磁滞损耗和最大微分磁导率）以及涡流输出（感应电压、归一化阻抗和相角）作为距末端淬火表面距离的函数，并且结果显示与通过传统硬度测试获得的数据明显一致。此外，利用广义回归神经网络，从磁滞回线和涡流方法获得的磁数据可用于使用几个训练数据点准确估计给定样品的硬度分布中的结果。本文表明，将所提出的无损方法与 Jominy 端淬试验相结合，有助于对钢样品进行准确的无损淬透性测定，同时减少试验过程的时间和成本。