US 5,467,655 AGranted

Method for measuring properties of cold rolled thin steel sheet and apparatus therefor

AssigneeNippon Steel Corporation

InventorsTakao Hyoguchi, Katsuhiro Kawashima

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Abstract

A method for measuring properties of a cold rolled thin steel sheet, comprising the determination, by using a resonant electromagnetic ultrasonic wave sensor for a standing wave, of the ratio of a thickness resonant frequency of a transverse ultrasonic wave propagating within a cold rolled thin steel sheet in the direction of thickness while polarized in a direction parallel to the direction of rolling to a thickness resonant frequency of a longitudinal ultrasonic wave propagating within the cold rolled thin steel sheet in the direction of thickness, and the ratio of a resonant frequency of a transverse ultrasonic wave propagating within the cold rolled thin steel sheet in the direction of thickness while polarized in a direction normal to the direction of rolling to a thickness resonant frequency of a longitudinal ultrasonic wave propagating in the direction of thickness, and approximately determining the Young's modulus and the Lankford value according to a computing formula using the resultant two measured -ratio values, the sound speed ratio of a SH0 plate wave regarded as a constant value and a known value of modulus of elasticity; and an apparatus for measuring properties of a cold rolled thin steel sheet comprising an electromagnetic ultrasonic wave device, a computing device and a controlling device for executing the measurement of properties and the computation.

Claims5

Dependent claims

A method for measuring properties of a cold rolled thin steel sheet wherein said cold rolled thin steel sheet has a rolling direction and a thickness, with the thickness having a direction perpendicular to the rolling direction, said method comprising:

determining, as a first thickness resonant frequency, a resonant frequency of a first transverse ultrasonic wave propagating within the cold rolled thin steel sheet in the thickness direction, said first transverse ultrasonic wave being polarized in a direction parallel to the rolling direction;
determining, as a second thickness resonant frequency, a resonant frequency of a first longitudinal ultrasonic wave propagating within the cold rolled thin steel sheet in the thickness direction;
determining, as a first ratio, a ratio of said first thickness resonant frequency to said second thickness resonant frequency;
determining, as a third thickness resonant frequency, a resonant frequency of a second transverse ultrasonic wave propagating within the cold rolled thin steel sheet in the thickness direction, said second transverse ultrasonic wave being polarized in a direction normal to the rolling direction;
determining, as a second ratio, a ratio of said third thickness resonant frequency to said second thickness resonant frequency;
regarding as a constant value a third ratio, said third ratio being a ratio of a SHO plate wave velocity propagating within the cold rolled thin steel sheet in a direction at 45.degree. to the rolling direction to a SHO plate wave velocity propagating within the cold rolled thin steel sheet in a direction parallel to or normal to the rolling direction;
computing in-plane average value of Young's moduli and in plane average value of Lankford values of the cold rolled thin steel sheet from said three ratios and a known modulus of elasticity of a single crystal of iron.

4 more elements

An apparatus for measuring properties of a cold rolled thin steel sheet, said apparatus including:

at least one electromagnetic ultrasonic wave device having a resonant electromagnetic wave sensor to measure thickness resonant frequency ratios, said cold rolled thin steel sheet having a rolling direction and a thickness with the thickness having a direction perpendicular to the rolling direction;
means for measuring, as a first, thickness resonant frequency, a resonant frequency of a first transverse ultrasonic wave propagating within the cold rolled thin steel sheet in the thickness direction, said first transverse ultrasonic wave being polarized in a direction parallel to the rolling direction;
means for measuring, as a second thickness resonant frequency, a resonant frequency of a longitudinal ultrasonic wave propagating within the cold rolled thin steel sheet in the thickness direction;
means for measuring, as a first ratio, a ratio of said first thickness resonant frequency to said second thickness resonant frequency;
means for measuring, as a third thickness resonant frequency, a resonant frequency of a second transverse ultrasonic wave propagating within the cold rolled thin steel sheet in the thickness direction, said second transverse ultrasonic wave being polarized in a direction normal to the rolling direction;
means for measuring, as a second ratio, a ratio of said third thickness resonant frequency to said second thickness resonant thickness frequency;
means for regarding as a constant value a third ratio, said third ratio being a ratio of a SHO plate wave velocity propagating within said cold rolled thin steel sheet in a direction at 45.degree. to the rolling direction to a SHO plate wave velocity propagating within said cold rolled thin steel sheet in a direction parallel to or normal to the direction of rolling;
means for computing in-plane average value of Young's moduli and in-plane average value of Lankford values of the cold rolled thin steel sheet from said three ratios and from a known modulus of elasticity of a single crystal of iron.

5 more elements

Dependencies are inferred from the claim text.