What are the common NDT methods? What are the advantages and disadvantages?

Date：2023-03-06 18:24:36Views：498

Non-destructive testing is an indispensable and effective tool for industrial development, which to some extent reflects the level of industrial development of a country, and its importance has been recognized. It is the general name of all technical means to detect whether there are defects or nonuniformities in the inspected object by using the acoustic, optical, magnetic and electrical characteristics without damaging or affecting the service performance of the inspected object, give the size, location, nature and quantity of the defects, and then determine the technical status of the inspected object (such as qualified or not, residual life, etc.). To help you understand, the following content is organized by Chuangxin Testing Network for your reference.

Common NDT methods

Radiographic inspection (RT), ultrasonic inspection (UT), magnetic particle inspection (MT) and liquid penetrant inspection (PT). Other NDT methods: eddy current testing (ET), acoustic emission testing (AT), thermal image/infrared (TIR), leakage testing (LT), alternating current field measurement technology (ACFMT), magnetic flux leakage testing (MFL), far-field testing and testing method (RFT), etc.

1、 Radiographic nondestructive testing

Advantages of radiographic nondestructive testing:

1. It can visually display the shape and size of defects, and the test results are convenient for long-term storage

2. High sensitivity to internal volumetric defects

3. It is applicable to the in-situ inspection of structural parts without large disassembly

Disadvantages of radiographic nondestructive testing:

1. Radiation can damage personnel, and protective measures must be taken

2. The detection cycle is long and the results cannot be obtained in real time. It is mainly applicable to the internal defect detection of components

2、 Ultrasonic nondestructive testing

Advantages of ultrasonic nondestructive testing:

1. High sensitivity to surface defects in the workpiece

2. Convenient for on-site inspection

3. Test results can be obtained in time

Disadvantages of ultrasonic nondestructive testing:

1. The defect display is not intuitive, and it is difficult to identify and quantify the defect

2. Have higher requirements on the skills of operators

3. The coupling agent required is mainly applicable to internal defect detection of components

3、 Magnetic particle nondestructive testing

Advantages of magnetic particle nondestructive testing:

1. It has high inspection sensitivity, and the minimum width of detectable defects is 0.1 μ m

2. It can visually display the position, shape and size of defects

3. The inspection is almost independent of the size and shape of the workpiece

Disadvantages of magnetic particle nondestructive testing:

1. Only the defects on the surface and near the surface of ferromagnetic materials can be inspected, and the inspection depth is usually only 1-2 mm

2. Magnetic suspension may cause environmental pollution

3. Not conducive to on-site inspection, applicable to surface and near-surface defect detection

4、 Eddy current nondestructive testing

Advantages of eddy current NDT:

1. The most widely used, convenient for on-site detection

2. Low requirements for workpiece surface

Disadvantages of eddy current NDT:

1. It is greatly affected by the shape of the workpiece

2. Low detection efficiency

3. The defect display is not intuitive and difficult to be qualitative and quantitative

4. Only surface and near-surface defects can be detected. Applicable to surface and near-surface defect detection

5、 Penetrant NDT

Advantages of penetrant NDT:

1. It does not need complex equipment and is easy to operate, especially suitable for on-site detection

2. High inspection sensitivity and intuitive defect display

3. It can detect surface opening defects in all directions of complex workpiece at one time

Defects of penetrant NDT:

1. It can only be used for the inspection of surface open defects of dense materials, and has high requirements for the surface finish to be inspected

2. High requirements for operating skills of operators

3. It will cause environmental pollution. It is applicable to surface opening defect detection

Each country, region and institution has different requirements for NDT training qualification certification. Personnel engaged in NDT need to receive training and obtain qualification before taking up their posts with certificates. So today's content will be shared here. If you feel that the content is helpful to you, please pay attention to Chuangxin Testing. We will provide you with more industry information