Abstract: A method for detecting a crater end of a continuously cast product, including installing an ultrasonic shear wave sensor for transmitting an ultrasonic shear wave to the continuously cast product and receiving the transmitted ultrasonic shear wave in a continuous casting machine, detecting based on variations of an ultrasonic signal received by the ultrasonic shear wave sensor that the crater end of the cast product is matched with the installed position of the ultrasonic shear wave sensor, calibrating a physical property value used in a calculation based on a heat condition equation such that the crater end computed based on the heat condition equation using casting conditions at that time is matched with the installed position of the ultrasonic shear wave sensor, and after the calibration, determining the crater end by the calculation based on the heat condition equation under respective casting conditions by using the calibrated physical property value.

Abstract: A method for detecting a crater end of a continuously cast product including installing an ultrasonic shear wave sensor for transmitting an ultrasonic shear wave to a cast product and receiving the transmitted ultrasonic longitudinal wave and an ultrasonic longitudinal wave sensor for transmitting an ultrasonic longitudinal wave to the cast product and receiving the transmitted ultrasonic longitudinal wave at the same position in a continuous casting machine or at positions apart from each other in a casting direction, but at the same position in a transverse direction of the cast product, detecting based on variations of an ultrasonic signal received by the ultrasonic shear wave sensor that the crater end of the cast product is matched with the installed position of the ultrasonic shear wave sensor, calibrating a calculation formula for determining the crater end and determining the crater end.

Abstract: An ultrasonic flaw detection is performed to a welded portion 2 of a pipe body 1, a defect detection threshold value is determined based on the signal intensity difference between the total area of the defects existing in the region of an ultrasonic beam on a welded surface and an artificial defect, and a quality control of the pipe body is performed based on the defect detection threshold value. An equivalent defect diameter is determined from the defect density on the welded surface of the welded portion of the pipe body in a pipe axis direction and the area of the ultrasonic beam on the welded surface based on the total area of the defects existing in the region of the ultrasonic beam, and the defect detection threshold value is determined based on the equivalent defect diameter and the signal intensity difference of the artificial defect.

Abstract: The present invention has a structure capable of detecting the scattered-type penetrator having oxides each with the size of several ?m sparsely and widely dispersed. Specifically, the structure includes a wave transmission unit 6 for transmitting an ultrasonic wave to the welded surface of the welded portion 2 in a pipe axial direction of the pipe 1 such that the beam width of a transmission beam 8 is brought into a range from 0.5 mm to 2.5 mm, and a wave reception unit 7 for receiving at least a portion of the reflection wave (reception beam 9) at the welded surface. The wave transmission unit 6 and the wave reception unit 7 include transmission/reception units formed of different groups of transducer elements on at least one or more array probes 5 arranged in the circumferential direction of the pipe.

Abstract: According to the present invention, penetrators can be adequately determined as flaws. In particular, a welded zone of a pipe is subjected to ultrasonic flaw detection at least in a pipe axial direction, and the quality of the pipe is evaluated using observed values in units of a predetermined area in a pipe thickness direction and the pipe axial direction. The length of one side of the predetermined area is an ultrasound beam width or more and a pipe thickness or less. The quality of the pipe can be evaluated while shifting the predetermined area in the pipe axial direction by using an average value of the observed values within the predetermined area. The length of one side of the predetermined area can be made an ultrasound beam width or more and a pipe thickness or less.

Abstract: A method for manufacturing an electric resistance steel pipe having a good toughness at a welded portion is provided, the method being capable of stably manufacturing an electric resistance welded steel pipe having a desirable toughness at a welded portion although a steel strip serving as a base material has a dimensional variation. Groove shapes and are applied to edges and of an open pipe, an edge shape monitor continuously captures images of the edges and immediately before electric resistance welding, and the captured images are input to an arithmetic processing unit for image processing.

Abstract: Disclosed are an ultrasonic testing system and an ultrasonic testing technique for a pipe member capable of detecting minute flaws of several hundreds of microns or less located at positions in the wall thickness inside portion of a welded portion of a seam-welded pipe and the like without omission and further easily setting optimum conditions when the size of the pipe is changed. A transmitting beam, which is focused to the welded portion at an oblique angle, is transmitted using a part of the group of transducer elements of a linear array probe as a group of transducer elements for transmission, a receiving beam, which is focused at the focusing position of the transmitting beam at an oblique angle, is formed using the transducer elements of a portion different from the above group of transducer elements for transmission as a group of transducer elements for reception, and a flaw echo is received from the welded portion.

Abstract: A manufacturing method for a continuously cast product of steel includes the steps of detecting a position of a crater end of the product by measuring a solidification state of the continuously cast product using a sensor which is not a contact with the product, and controlling at least one condition selected from the conditions of the casting speed and the quantity of secondary cooling water based on the detected position of the crater end. The method for measuring a solidification state of the continuously cast product includes the steps of cooling the product until the surface layer portion is ? transformed, transmitting transverse waves of electromagnetic ultrasonic waves to the colled product as a transmitting signal, receiving a signal after said transmitting signal propagates in said product as a receiving signal, and judging the solidification state of said product based on the receiving signal.

Abstract: In continuous casting of steel, the invention is able to accurately detect a crater end only from a value measured by a sensor without needing calibration based on the slab rivet method, etc. An ultrasonic shear wave sensor 6, 8 for transmitting an ultrasonic shear wave to a cast product 1 and receiving it and an ultrasonic longitudinal wave sensor 7, 9 for transmitting an ultrasonic longitudinal wave to the cast product and receiving it are installed at the same position in a continuous casting machine or at two positions apart in a casting direction but at the same position in a transverse direction of the cast product. From variations of an ultrasonic signal received by the ultrasonic shear wave sensor, it is detected that a crater end 4 of the cast product is matched with the installed position of the ultrasonic shear wave sensor.

Abstract: A manufacturing method for a continuously cast product of steel includes the steps of detecting a position of a crater end of the product by a method for measuring a solidification state of continuously cast product using a sensor arranged so as to be in non-contact with the product, and controlling at least one condition selected from the conditions of the casting speed and the quantity of secondary cooling water based on the detected position of crater end.

Abstract: A manufacturing method for a continuously cast product of steel includes the steps of detecting a position of a crater end of the product by a method for measuring a solidification state of the continuously cast product using a sensor arranged so as to be in non-contact with the product, and controlling at least one condition selected from the conditions of the casting speed and the quantity of secondary cooling water based on the detected position of crater end.

Abstract: A manufacturing method for a continuously cast product of steel includes the steps of detecting a position of crater end of product by a method for measuring a solidification state of continuously cast product using a sensor arranged so as to be in non-contact with the product, and controlling at least one condition selected from the conditions of the casting speed and the quantity of secondary cooling water based on the detected position of crater end. The method for measuring a solidification state of continuously cast product includes the steps of cooling the product until a surface layer portion thereof is ? transformed, transmitting transverse waves of electromagnetic ultrasonic waves to the cooled product, receiving the signal after the transmitting signal propagates in the product, and judging the solidification state of the product based on the received signal.

Abstract: A manufacturing method for a continuously cast product of steel includes the steps of detecting a position of crater end of product by a method for measuring a solidification state of continuously cast product using a sensor arranged so as to be in non-contact with the product, and controlling at least one condition selected from the conditions of the casting speed and the quantity of secondary cooling water based on the detected position of crater end. The method for measuring a solidification state of continuously cast product includes the steps of cooling the product until a surface layer portion thereof is ? transformed, transmitting transverse waves of electromagnetic ultrasonic waves to the cooled product, receiving the signal after the transmitting signal propagates in the product, and judging the solidification state of the product based on the received signal.

Abstract: The present invention provides a manufacturing method for a continuously cast product of steel comprising the steps of: detecting a position of crater end of product by a method for measuring a solidification state of continuously cast product using a sensor arranged so as to be in non-contact with the product; and controlling at least one condition selected from the conditions of the casting speed and the quantity of secondary cooling water based on the detected position of crater end, the method for measuring a solidification state of continuously cast product comprising the steps of: cooling the product until a surface layer portion thereof is &agr; transformed; transmitting transverse waves of electromagnetic ultrasonic waves to the cooled product; receiving the signal after the transmitting signal propagates in the product; and judging the solidification state of the product based on the received signal.

Abstract: In an ultrasonic inspection apparatus for detecting a flaw present in a target object (2) on the basis of an echo signal (b) from the target object (2), a high-frequency echo signal (b) output from an ultrasonic transmit-receive unit (1) is A/D-converted at a high sampling frequency (f.sub.S) in only a predetermined measurement time interval (T.sub.M) in a repetitive period (T.sub.O) of an ultrasonic pulse (a) and is temporarily stored in a storage unit (12). Thereafter, the sampling data is read out at a read frequency (f.sub.R) lower than the sampling frequency (f.sub.S). A digital signal process for noise reduction using a first digital filter (18) or a synchronous adding/averaging circuit (27) is performed to only data in the measurement time interval (T.sub.M). As a result, noise included in the echo signal (b) is considerably reduced while on-line inspection is kept performed.