GB/T 34370.3-2017Nondestructive testing of amusement equipments—Part 3: Magnetic particle testing (English PDF)

3.1 Excessive background

Magnetic particle indication background due to excessive magnetic field strength, excessive magnetic ink concentration and rough or contaminated workpiece surface, which impedes the analysis evaluation of magnetic particle indication.

3.2 Relevant indication

Magnetic particle indication formed by the f the flux leakage field absorbing magnetic particle due to defects (crack, incomplete fusion, porosity, slag inclusion, etc.) during magnetic particle testing is called relevant indication. It is also known as defect indication.

3.3 Non-relevant indication

Magnetic particle indication formed by the flux leakage field absorbing magnetic particle due to the magnetic field cross-section mutation and the difference in magnetic permeability of the material is called non-relevant indication.

3.4 False indication

Magnetic particle indication that is not formed by the flux leakage field absorbing magnetic particle.

7.1 Magnetic particle testing equipment

7.1.1 Basic requirements

The magnetic particle testing equipment shall comply with the provisions of JB/T 8290.

7.1.2 Power-off phase controller

When using the residual magnetic field method for testing, the AC flaw detector shall be equipped with power-off phase controller.

7.1.3 Black light irradiance and wavelength

When using the fluorescent magnetic particle testing, the black light (UV-A) used shall comply with the provisions of GB/T 5097, and the irradiation intensity on the surface of the workpiece to be tested shall be greater than or equal to 1000 µW/cm2.Its wavelength shall be 315 nm to 400 nm, and the peak wavelength is approximately 365 nm.

7.1.5 Auxiliary equipment

Generally include the following equipment.

7.2 Magnetic particle, carrier fluid and magnetic ink

7.2.1 Magnetic particle

The magnetic particle shall have high magnetic permeability, low coercivity and low residual magnetic field, and shall have a high contrast with the surface color of the workpiece to be tested. Other requirements for magnetic particle size and performance shall be in accordance with JB/T 6063.

7.2.3 Magnetic ink

The concentration of the magnetic ink shall be determined according to factors such as the type, the particle size, the application method of magnetic particle, and the surface state of the workpiece to be tested.

7.3 Shims

7.3.1 Standard shims

7.3.2 Magnetic field indicator

The magnetic field indicator is a rough calibration tool used to indicate whether the aspect of the magnetic field and the effective testing area on the surface of the workpiece to be tested, and the magnetization method are correct, but it cannot be used as a quantitative indication of the strength of the magnetic field

7.5 Yoke lifting power calibration

The lifting power of the yoke shall be calibrated at least once every six months. It shall be re-calibrated after the yoke damage is repaired.

7.6 Auxiliary instrument calibration

Auxiliary instruments for magnetic particle testing, such as black light irradiance The maximum gap is 0.8

8.1 General testing process procedures

Organizations engaged in the magnetic particle testing of amusement equipment shall formulate general testing process procedures in accordance with the requirements of GB/T 34370.1 and this Part, and the contents shall at least include the following elements.

8.2 Testing process card

For the magnetic particle testing of each type of workpiece, the magnetic particle testing process card shall be formulated according to the actual situation and in accordance with GB/T 34370.1, this Part and the general testing

9.1 Preparation before testing

9.1.1 Data review

The data review shall include the following. […]

9.1.2 Site survey

For amusement equipment in use, before the implementation of the testing, the site where the equipment to be tested locates shall be surveyed, the auxiliary conditions for the implementation of the testing shall be determined, and all factors that may affect the testing shall be identified. The interference of these factors shall be avoided as far as possible during the testing.

9.1.3 Preparation of test process cards

In accordance with 8.2.

9.1.5 Contrast aid paints

To enhance contrast contrast aid paints may be used.

9.2 Magnetizing electric current type and its selection

Common types of current for magnetic particle testing are. AC, rectified current (full-wave rectification, half-wave rectification) and DC. Required by the magnetization specification, the AC magnetization current value is effective value, and the rectified current value is average value. See Annex A for the waveform of magnetizing electric current, the ammeter indication, and the conversion relationship.

9.3 Magnetization directions

9.4 Magnetization specifications

9.4.1 Yoke method

9.4.1.1 The magnetic pole spacing of the yoke should be controlled between 75 mm and 200 mm. The effective width is within 1/4 pole distance on both sides of the two-pole connection. The magnetized area shall have an overlap of not less than 10 % each time. When the magnetic pole spacing of the yoke is less than 75 mm, care shall be taken that the magnetic particle forms an non-relevant indication around the electrode.

9.4.1.2 When the workpiece is magnetized by the yoke method, its magnetizing electric current shall be selected according to the measured results of the standard shim. If the workpiece is magnetized with a fixed yoke, the measured results of the standard shim shall be used to verify whether the sensitivity meets the requirements.

9.4.2 Coil method

9.5 Testing method

9.5.1 Continuous method

When the continuous method is used, the magnetization of the workpiece to be tested, the process of applying the magnetic particle, and the observation of the magnetic particle indication shall be completed within the magnetization current flow time. The current flow time is 1 s ~ 3 s, and the magnetization can be stopped after the magnetic ink is stopped being applied for at least 1 s. To ensure the magnetization effect, the magnetization shall be repeated at least twice.

9.5.2 Residual magnetic field method

9.10 Testing record

The magnetic particle testing record shall include at least the contents specified in 8.2 and Clause 13. […]