Ultrasonic flaw detection process for hardened layer of forged steel cold rolling work roll

Abstract

The present application relates to a kind of for solving the defect echo that exists in the hardened layer of forged steel cold rolling work roll cannot be distinguished accurately to judge the forged steel cold rolling work roll hardened layer ultrasonic flaw detection detection process, with 10mm deep series blind hole as artificial reflector to make reference test block, using wedge block of shear wave oblique probe to be ground into the shape of the surface of work roll, with this series of shear wave oblique probe circumferential detection, make probe main sound beam aim at the subcutaneous 10mm series blind hole of reference test block hardened layer, make distance-amplitude correction curve;Series shear wave oblique probe is installed on roller grinder measuring carriage, and forged steel cold rolling work roll process and ultrasonic flaw detection detection process are carried out simultaneously;In forged steel cold rolling work roll process, forged steel cold rolling work roll rotates and moves, and the moving speed is not greater than 150mm / s, and the flaw detection base scan speed is adjusted according to horizontal 1:2, and the surface of forged steel cold rolling work roll hardened layer is detected circumferentially by ultrasonic probe, and defect echo is quickly judged, the detection efficiency and the accuracy of detection result are improved, and forged steel cold rolling work roll hardened layer defect is found in time.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic testing technology for metallic materials, specifically relating to an ultrasonic flaw detection process for the hardened layer of cold-rolled forged steel work rolls, which solves the problem of inaccurate identification of defect echoes in the hardened layer of cold-rolled forged steel work rolls. Background Technology

[0002] For cold-rolled forged steel work rolls with a hardened layer thickness ≤15mm, common defects in the hardened layer include point-like, line-like, and fine hairline cracks. In the ultrasonic flaw detection process specified in GB / T13314-2008 (for cold-rolled forged steel work rolls), using the longitudinal wave Φ2 equivalent sensitivity of Zone I (hardened layer) in Grade A, these defects are often misidentified. This results in existing detection processes failing to meet the requirements for flaw detection of the hardened layer of cold-rolled forged steel work rolls. Therefore, a new ultrasonic flaw detection process for the hardened layer of cold-rolled forged steel work rolls is needed to solve the problem of difficult defect identification in the hardened layer and improve the ultrasonic detection rate of point-like, line-like, and hairline crack defects that cannot be identified by the longitudinal wave Φ2 equivalent sensitivity of Zone I (hardened layer) in Grade A of GB / T13314-2008. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and provide an effective ultrasonic flaw detection process for identifying defects in the hardened layer of cold-rolled forged steel work rolls, thereby ensuring the accuracy of ultrasonic flaw detection.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] An ultrasonic flaw detection process for the hardened layer of a cold-rolled forged steel work roll is disclosed. In this process, a series of 10mm deep blind holes are used as artificial reflectors to create a reference test block. A shear wave angle probe wedge is ground to a shape that matches the curved surface of the work roll. This series of shear wave angle probes is used for circumferential detection, aligning the main acoustic beam of the probe with the series of 10mm deep blind holes beneath the hardened layer of the reference test block, and a distance-amplitude correction curve is generated. The series of shear wave angle probes are mounted on the measuring slide of a roll grinding machine. The rough or fine grinding process of the cold-rolled forged steel work roll is performed simultaneously with the ultrasonic flaw detection process. During the rough or fine grinding process, the cold-rolled forged steel work roll rotates at a speed not exceeding 150mm / s. The flaw detection time base scanning speed is adjusted horizontally at a ratio of 1:2. The ultrasonic probe performs circumferential detection on the surface of the hardened layer of the cold-rolled forged steel work roll, quickly identifying defect echoes.

[0006] The specific testing process steps are as follows:

[0007] Step 1) Use an A-type pulse reflection ultrasonic flaw detector and a series of shear wave angle probes β70º, β65º, β60º, and β57º, with a frequency of 4 to 10 MHz; the probe chip size is (9×9 mm) to (13×13 mm), and the shear wave angle probe wedge should be ground to match the curved surface of the cold-rolled forged steel work roll;

[0008] Step 2) Design and fabricate a reference test block:

[0009] Step 2.1) The reference test block is taken from the cold rolling work roll of the forged steel under test. Its material, curvature, surface roughness, heat treatment condition, and hardened layer condition are the same as those of the cold rolling work roll of the forged steel under test.

[0010] Step 2.2) The reference test block is a cylindrical blank with a series of blind holes of Φ0.3mm (diameter) × 10mm (depth) to Φ0.5mm (diameter) × 10mm (depth) machined on it as artificial defects. On one end face of the cylindrical blank, three blind holes with a depth of 10mm are evenly distributed around the axis of the cylinder. The lines connecting the axes of adjacent blind holes to the axis of the cylinder are 120mm apart. 0 The radial distances from the center of the blind holes to the outer circle of the cylinder are 1mm, 3mm, and 5mm respectively. The blind hole with a distance of 1mm has a diameter of φ0.3mm, and the remaining blind holes have a diameter of φ0.5mm. On the other end face of the cylindrical blank, three blind holes with a diameter of φ0.5mm and a depth of 10mm are distributed around the cylinder's center. The lines connecting the centers of adjacent blind holes to the cylinder's center are 120mm apart. 0 The radial distances from the center of the blind hole to the outer circle of the cylinder are 7mm, 9mm, and 11mm, respectively.

[0011] Step 3) Determine the coupling agent to be used for testing: Since the ultrasonic flaw detection process is designed to be carried out simultaneously with the rough grinding or fine grinding process of the cold rolling work roll of forged steel, the coupling agent to be used for testing is the grinding machine coolant.

[0012] Step 4) Ultrasonic probe calibration and distance-amplitude correction curve creation: Use a series of shear wave angle probes for circumferential detection, aligning the main beam of the probe with a 1mm subcutaneous artificial Φ0.3mm×10mm blind hole in the hardened layer of the reference test block, to calibrate the β70º probe. Correspondingly, calibrate the β65º probe with subcutaneous artificial Φ0.5mm×10mm blind holes (3mm-5mm), and the β60º probe with subcutaneous artificial Φ0.5mm×10mm blind holes (7mm-9mm). For comparison, calibrate the β57º probe with subcutaneous artificial Φ0.5mm×10mm blind holes (≥11mm) in area I of the test block. Collect blind hole echoes one by one from the shallowest to the deepest part of the hardened layer using the series of shear wave angle probes. Adjust the blind hole echoes to 80% of the height of the ultrasonic flaw detector display screen to create a distance-amplitude correction curve. Use this distance-amplitude correction curve to determine the acceptance limit reference line for ultrasonic testing.

[0013] Step 5) The ultrasonic flaw detection process is performed simultaneously with the rough or fine grinding process of the forged steel cold-rolled work roll: A series of shear wave angle probes are installed on the measuring slide of the roll grinding machine. The measuring slide of the roll grinding machine is driven by a servo motor to achieve fast and slow speed movement; the position of the slide is detected by an LS186 linear grating; the ultrasonic flaw detection process is performed simultaneously with the rough or fine grinding process of the forged steel cold-rolled work roll; during the rough or fine grinding process of the forged steel cold-rolled work roll, the forged steel cold-rolled work roll rotates... The ultrasonic probe on the measuring carriage is rotated and used to perform circumferential inspection on the surface of the hardened layer of the cold-rolled forged steel work roll. The moving speed of the cold-rolled forged steel work roll should not exceed 150 mm / s. There should be a certain overlap between two adjacent scans, and the overlap width should not be less than 15% of the scan width. During the inspection, the flaw detection time base scanning speed is adjusted to 1:2 horizontally. If no defect signal exceeds the acceptance limit reference line in the ultrasonic inspection of the hardened layer of the cold-rolled forged steel work roll, the ultrasonic flaw detection of the hardened layer of the cold-rolled forged steel work roll is qualified.

[0014] The axes of all the blind holes are parallel to the axis of the cylinder, with a parallelism not exceeding ±0.03 mm. The limit deviations for the diameter and depth of the blind holes are ±0.05 mm, and the surface roughness Ra of the blind holes is ≤3.2 μm. All blind holes are located within the hardened layer of the reference test block.

[0015] The beneficial effects of this invention are as follows:

[0016] In ultrasonic flaw detection of the hardened layer of cold-rolled forged steel work rolls, this process can quickly determine the defect echo, improve the detection efficiency and the accuracy of the detection results, and promptly detect defects in the hardened layer of cold-rolled forged steel work rolls. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the location of the blind hole on the end face 1 of the reference test block for the detection process of this invention.

[0018] Figure 2 This is a schematic diagram showing the location of the blind hole on the end face 2 of the reference test block for the detection process of this invention.

[0019] Figure 3 This is a top view of the blind hole location of the reference test block in this invention.

[0020] The figure shows: 1. Reference test block, 2. Blind hole. Detailed Implementation

[0021] Example 1: An ultrasonic flaw detection process for the hardened layer of cold-rolled forged steel work rolls, the specific detection process steps are as follows:

[0022] Step 1) The instrument used in this process is: A-type pulse reflection ultrasonic flaw detector, model: EPOCH 1000, using a series of shear wave angle probes β70º, β65º, β60º, and β57º, with a frequency of 4~10MHZ; the probe chip size is (9×9mm)~(13×13mm), and the shear wave angle probe wedge should be ground to match the shape of the MC3 forged steel cold rolling work roll.

[0023] Step 2) Design and fabrication of a reference test block: The reference test block is made from the tested MC3A forged steel cold-rolled work roll, with a steel grade of MC3A and a specification of 310×2500mm. Its material, curvature, surface roughness, heat treatment condition, and hardened layer are identical to those of the tested MC3A forged steel cold-rolled work roll. The MC3 forged steel cold-rolled work roll has a series of blind holes on the reference test block with artificial defects ranging from Φ0.3mm (diameter) × 10mm (depth) to Φ0.5mm (diameter) × 10mm (depth). On the cylindrical end face 1 of the reference test block, three blind holes with a depth of 10mm are distributed around the cylinder's axis, with the lines connecting the centers of adjacent blind holes to the cylinder's axis spaced 120mm apart. 0 The radial distances from the axis of the blind hole to the outer circle of the cylinder are 1mm, 3mm, and 5mm, respectively. The diameter of the blind hole with a distance of 1mm is φ0.3mm, and the diameter of the other blind holes is φ0.5mm.

[0024] On the cylindrical end face 2 of the reference test block, three blind holes with a diameter of φ0.5mm and a depth of 10mm are evenly distributed around the axis of the cylinder. The lines connecting the axes of adjacent blind holes to the axis of the cylinder are 120mm apart. 0 The radial distances from the center of the blind hole to the outer circle of the cylinder are 7mm, 9mm, and 11mm, respectively.

[0025] The axis of the blind hole is parallel to the axis of the cylinder, with a parallelism not exceeding ±0.03 mm. The limit deviation of the diameter and depth of the blind hole is ±0.05 mm, and the surface roughness Ra of the blind hole is ≤3.2 μm. All blind holes are located within the hardened layer of the reference test block.

[0026] Step 3) The coupling agent used for testing is grade 69-1 cooling emulsion.

[0027] Step 4) Probe Calibration and Distance-Amplitude Correction Curve Creation: Using a series of shear wave angle probes for circumferential detection, align the main beam of the probe with a 1mm subcutaneous artificial Φ0.3mm×10mm blind hole in the hardened layer of the reference test block to calibrate the β70º probe. Correspondingly, calibrate the β65º probe with subcutaneous artificial Φ0.5mm×10mm blind holes ranging from 3mm to 5mm; and calibrate the β60º probe with subcutaneous artificial Φ0.5mm×10mm blind holes ranging from 7mm to 9mm. For comparison, calibrate the β57º probe with subcutaneous artificial Φ0.5mm×10mm blind holes ≥11mm in area I of the reference test block. Collect blind hole echoes one by one from the shallowest to the deepest part of the hardened layer using the series of shear wave angle probes. Adjust the blind hole echoes to 80% of the height of the ultrasonic flaw detector display screen to create a distance-amplitude correction curve. Use this distance-amplitude correction curve to determine the acceptance limit reference line for ultrasonic testing.

[0028] Step 5) The fine grinding process of the inspected MC3A forged steel cold-rolled work roll is carried out on a roll grinding machine M1350C 500×3000: a series of shear wave angle probes are installed on the measuring slide of the roll grinding machine M1350C 500×3000. The measuring slide of the roll grinding machine is driven by a servo motor to achieve fast and slow speed movement. The position of the slide is detected by an LS186 linear grating; the fine grinding process of the inspected MC3A forged steel cold-rolled work roll is carried out simultaneously with the ultrasonic flaw detection process; during the fine grinding process, the MC3A forged steel cold-rolled work roll rotates and moves, and the ultrasonic probe on the measuring slide performs circumferential detection on the surface of the hardened layer of the forged steel cold-rolled work roll; the moving speed of the forged steel cold-rolled work roll is not greater than 150 mm / s; there should be a certain overlap between two adjacent scans, and the overlap width should not be less than 15% of the scan width; during the detection process, the flaw detection time base scanning speed is adjusted at a horizontal ratio of 1:2.

[0029] In ultrasonic testing of the hardened layer of cold-rolled forged steel work rolls, if no defect signal exceeds the acceptance limit reference line, the ultrasonic flaw detection of the hardened layer of cold-rolled forged steel work rolls is qualified.

Claims

1. A process for ultrasonic inspection of hardened layer of forged steel cold rolling work roll, characterized in that: In the detection process, a series of blind holes with a depth of 10 mm are used as artificial reflectors to make reference test blocks. A transverse wave oblique probe wedge is ground to match the shape of the work roll surface. The probe is installed on the measuring carriage of the roll grinder, and the grinding process and the ultrasonic detection process are carried out simultaneously. During the grinding process, the work roll rotates and moves at a speed not greater than 150 mm / s. The horizontal scanning speed is adjusted to 1:2, and the ultrasonic probe detects the surface of the work roll in the circumferential direction to quickly determine the defect echo. The specific detection process steps are as follows: Step 1), use an A-type pulse reflection ultrasonic flaw detector and a series of transverse wave oblique probes β70º, β65º, β60º, β57º with a frequency of 4-10 MHz. The probe wafer size is selected to be (9×9 mm) to (13×13 mm). The wedge of the transverse wave oblique probe is ground to match the shape of the work roll surface. Step 2), design and make reference test blocks: Step 2.1), the reference test blocks are made of the work roll to be detected, and their material, curvature, surface roughness, heat treatment condition, and hardened layer condition are the same as those of the work roll to be detected. Step 2.2), the test block is a cylindrical blank, on which a series of blind holes with diameter Φ0.3mm×depth 10mm~diameter Φ0.5mm×depth 10mm are processed as artificial defects, on one end face of the cylindrical blank, 3 blind holes with depth 10mm are uniformly distributed with the cylindrical axis as the center, the connecting lines of the axis centers of adjacent blind holes and the cylindrical axis are separated by 120 0 , and the radial distances of the axis centers of the blind holes from the outer circle of the cylinder are 1mm, 3mm, 5mm in turn, wherein the diameter of the blind hole with distance 1mm is φ0.3mm, and the diameters of the remaining blind holes are φ0.5mm; on the other end face of the cylindrical blank, 3 blind holes with diameter φ0.5mm×depth 10mm are distributed with the cylindrical axis as the center, the connecting lines of the axis centers of adjacent blind holes and the cylindrical axis are separated by 120 0 , and the radial distances of the axis centers of the blind holes from the outer circle of the cylinder are 7mm, 9mm, 11mm in turn; Step 3), determine the coupling agent for detection: since the ultrasonic detection process is carried out simultaneously with the grinding process of the work roll, the coupling agent for detection is selected as the grinding coolant. Step 4), ultrasonic probe calibration and distance-amplitude correction curve making: use a series of transverse wave oblique probes to detect in the circumferential direction, so that the main sound beam of the probe is aligned with the 1 mm artificial Φ0.3 mm×10 mm blind hole under the hardened layer of the reference test block. The β70º probe is calibrated, and the corresponding 3-5 mm artificial Φ0.5 mm×10 mm blind hole under the skin is used to calibrate the β65º probe. The 7-9 mm artificial Φ0.5 mm×10 mm blind hole is used to calibrate the β60º probe, and the artificial Φ0.5 mm×10 mm blind hole under the skin of the reference test block I area is used to calibrate the β57º probe. The series of transverse wave oblique probes collect blind hole echoes from the hardened layer to the deep one by one. The blind hole echo is adjusted to 80% of the height of the ultrasonic flaw detector display screen, and the distance-amplitude correction curve is made. Through this distance-amplitude correction curve, the acceptance limit reference line of ultrasonic detection is determined. Step 5, the ultrasonic flaw detection process is carried out simultaneously with the rough grinding or fine grinding process of the forged steel cold rolling work roll: a series of oblique transverse wave probes are installed on a measuring slide of a roll grinder, the measuring slide of the roll grinder is driven by a servo motor to realize fast and slow movement through a pair of worm gears, a worm and a gear rack; the position of the slide is detected by a LS186 linear grating; the ultrasonic flaw detection process is carried out simultaneously with the rough grinding or fine grinding process of the forged steel cold rolling work roll; in the rough grinding or fine grinding process of the forged steel cold rolling work roll, the forged steel cold rolling work roll rotates and moves, and the ultrasonic probes on the measuring slide detect the surface of the hardened layer of the forged steel cold rolling work roll in a circumferential direction; the moving speed of the forged steel cold rolling work roll is not greater than 150 mm / s; there should be a certain overlap between adjacent two scans, and the overlap width is not less than 15% of the scan width; during the detection process, the base scan speed of the flaw detection is adjusted according to the horizontal 1:2; in the ultrasonic detection of the hardened layer of the forged steel cold rolling work roll, if there is no defect signal exceeding the acceptance limit reference line, the ultrasonic flaw detection of the hardened layer of the forged steel cold rolling work roll is qualified. The axis of each blind hole is parallel to the axis of the cylinder.

2. The process for ultrasonic inspection of quenched layer of forged steel cold roll work roll as claimed in claim 1 wherein the process is characterized by: The axis of each blind hole is parallel to the axis of the cylinder, the parallelism is not more than ±0.03 mm, the limit deviation of the diameter and depth of the blind hole is ±0.05 mm, the surface roughness Ra of the blind hole is ≤3.2 μm; the position of the blind hole is in the hardened layer of the test block. The axis of each blind hole is parallel to the axis of the cylinder. The axis of each blind hole is parallel to the axis of the cylinder, the parallelism is not more than ±0.03 mm, the limit deviation of the diameter and depth of the blind hole is ±0.05 mm, the surface roughness Ra of the blind hole is ≤3.2 μm; the position of the blind hole is in the hardened layer of the test block.

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