| 摘要 |
PURPOSE:To achieve a highly accurate measurement non-destructively in a short time, by placing a 2-phase structure steel plate having a martensite phase into an AC magnetic field meeting a specified requirement to determine the tensile strength of a steel plate, detecting the magnetic permeability thereof. CONSTITUTION:A steel strip 1 is magnetized with a magnetization coil 2. The magnetic permeability of the steel strip 1 is measured with a coil 3. The magnetic permeability in the ferrite and martensite phase varies with the intensity of a magnetic field and the difference in the magnetic permeability between both phases become greater in a specified magnetic field range. As the specific magnetic permeability in 250-2,500A/m indicates quantitative changes in the martensite efficiently. The strength of ferrite depends on the type of steel (rough components such as C, Si, Mn and P), the strength of the steel plate varies with the amount of martensite thereby enabling the estimate of the overall strength of the steel strip from the magnetic permeability. |
