Method for ultrasonic testing of forged and rolled steel bars
1 Scope
This document specifies the general requirements, instruments and equipment, reference blocks, testing regulations, testing procedures, evaluation of testing results, quality grade, testing record and report for ultrasonic testing of forged and rolled steel bars (hereinafter referred to as "steel bars").
This document is applicable to ultrasonic pulse reflection testing of steel bars with diameter not less than 6 mm, and may be used as a reference for forged bars or non-bars of other specifications or materials.
This document is not applicable to the testing of austenitic coarse-grained steel bars.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 9445 Non-destructive testing—Qualification and certification of NDT personnel
GB/T 12604.1 Non-destructive testing—Terminology—Terms used in Ultrasonic testing
GB/T 18694 Non-destructive testing—Ultrasonic inspection—Characterization of search unit and sound field
GB/T 18852 Non-destructive testing—Ultrasonic testing—Reference blocks and test procedures for the characterization of contact probe sound beams
JB/T 10061 Commonly used specification for A-mode ultrasonic flaw detector using pulse echo technique
JB/T 11731 Non-destructive testing—General specification for ultrasonic phased array probe
JJG 746 Ultrasonic flaw detectors
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 12604.1 apply.
4 General
4.1 Personnel qualification
Personnel engaged in ultrasonic testing of steel bars shall attend training according to GB/T 9445 or relevant documents and obtain ultrasonic testing qualification certificates; those who issue test reports shall obtain ultrasonic testing qualification certificates of Grade 2 or above.
4.2 Couplant
4.2.1 Water is generally used as a couplant in liquid immersion technology, and oil may also be used. The couplant shall be free of bubbles and foreign substances that affect ultrasonic testing. Appropriate rust inhibitor may be added to the couplant to prevent steel bar corrosion; and appropriate lubricant may be added to the couplant to reduce the bubbles formed on the steel rod and probe.
4.2.2 Couplants such as oil, grease, water and water-soluble gel should be used in contact technology, and the viscosity and surface wettability of couplants shall be sufficient to ensure that ultrasonic energy is well transmitted into steel bars.
5 Instruments and equipment
5.1 Ultrasonic tester
5.1.1 Performance test methods and requirements
The performance of ultrasonic tester shall be tested according to JB/T 10061 or JJG 746, and its indexes shall meet the following requirements:
——Vertical linearity: not greater than 5%;
——Horizontal linearity: not greater than 2%;
——Dynamic range: not less than 30 dB;
——Sensitivity allowance: not less than 42 dB;
——Attenuation error: up to ±1.0 dB/12 dB.
5.1.2 Alarms
Light and/or sound alarms should be used. The alarm shall be triggered by adjusting the amplitude of the ultrasonic signal received on the time baseline, and the alarm threshold level shall be adjustable.
5.2 Probe
5.2.1 The frequency of the probe shall meet the requirements of the ability and resolution of penetrating the steel bar under test, preferably 2 MHz to 10 MHz; the probe wafer diameter (side length) should not be greater than 28 mm; the focus mode should be adopted for immersion probe. However, other types of probes, such as phased array probes meeting the requirements of JB/T 11731, may be used as long as the testing requirements can be met.
5.2.2 When the liquid immersion method is adopted for testing, the angle controller and mechanical control device of the probe shall be easy to adjust.
5.2.3 Probe parameters should be tested according to the methods specified in GB/T 18694 and GB/T 18852.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General
5 Instruments and equipment
6 Reference block
7 Testing regulations
8 Testing procedures
9 Evaluation of testing results
10 Quality grade
11 Testing record and report
Bibliography
