DETERMINATION OF HARDENED METAL LAYER THICKNESS USING MAGNETIC METHOD

Abstract

The routine method to control metal surface layer is Vickers hardness test method. The existing nondestructive testing methods are based on measuring induction density and other magnetic quantities in magnetizer core. This causes the method error and restricts the ability to determine the structure of the processed material. The paper provides theoretical and experimental investigation of the method for controlling the hardened axis layer parameters by analyzing characteristics of stray magnetic field of the axis magnetized local surface area before and after rouletting. A method is proposed for determining the hardened metal layer thickness of the rolling stock axis, based on measuring the parameters of the magnetized local area stray magnetic field before and after processing. To justify the proposed method, mathematical modeling of stray magnetic field of the axis local magnetized section is performed before and after processing. Inspection for the hardened metal layer is performed using magnetization of the axis local segment with electromagnet, followed by measuring the stray magnetic field strength. The maximum value of the horizontal magnetic force is determined, which is an informative parameter. A mathematical model is developed for the magnetized section magnetic field, the results of numerical and field experiments are presented. The discrepancy between the experimental data and the results of theoretical calculations is estimated. The method makes it possible to control the thickness of the hardened metal layer and the quality of the hardening of the rolling stock axis.