Physical flaw detection is non-destructive testing without chemical changes.
First, what is non-destructive testing?
A: Non-destructive testing is a test method to check the surface and internal quality of the parts being inspected without damaging the working condition of the workpiece or raw materials.
Second, what are the common detection methods?
Answer: The commonly used non-destructive testing methods include: X-ray inspection, ultrasonic inspection, magnetic particle inspection, penetrant inspection, eddy current inspection, gamma ray inspection, fluorescent inspection, and color inspection.
Third, test the principle of magnetic particle inspection?
A: Its basic principle is: When the workpiece is magnetized, if there is a defect on the surface of the workpiece, magnetic leakage is generated due to the increased magnetic resistance at the defect, and a local magnetic field is formed, and the magnetic powder displays the shape and position of the defect here. Determine the presence of defects.
Fourth, test the type of magnetic particle inspection?
1, according to the workpiece magnetization direction, can be divided into circumferential magnetization method, longitudinal magnetization method, composite magnetization method and rotational magnetization method.
2, according to the use of different magnetizing current can be divided into: DC magnetization method, half-wave DC magnetization method, and AC magnetization method.
3, according to the detection of magnetic powder used in the preparation of different, can be divided into dry powder method and wet powder method.
Fifth, what are the defects of magnetic particle inspection?
A: Magnetic particle inspection equipment is simple, easy to operate, rapid inspection, high detection sensitivity, can be used to discover the surface or near surface defects of ferromagnetic materials nickel, cobalt and its alloys, carbon steel and certain alloy steel; Suitable for thin-walled parts or weld surface crack inspection, but also to reveal a certain depth and size of incomplete penetration defects; but difficult to find the pores, saggers and hidden in the depth of the weld defects.
Six, defect magnetic marks can be divided into several categories?
Answer: 1. Magnetic flaws of defects in various processes;
2, material slag brought about by the pattern of magnetic marks;
3, slag, pores bring a bit of magnetic marks.
Seven, the reasons for the occurrence of magnetic leakage?
Answer: Since the ferromagnetic material's magnetic permeability is much larger than the non-ferromagnetic material's magnetic permeability, the magnetic flux density after the workpiece is magnetized is B = μH to analyze, per unit area of ​​the workpiece through the B magnetic wire, and in the defect area The unit's area cannot allow the B magnetic flux to pass through, forcing part of the magnetic flux into the material below the defect. Other magnetic flux lines have to be forced out of the surface of the workpiece to form a leakage magnetic flux. The magnetic powder will be attracted by the magnetic flux leakage caused by this. .
VIII. Describe the influencing factors of magnetic flux leakage?
A: 1, the permeability of the defect: the smaller the magnetic permeability of the defect, the stronger the magnetic leakage.
2, magnetization magnetic field strength (magnetization force) size: the greater the magnetizing force, the stronger the magnetic flux leakage.
3. The shape and size of the workpiece to be inspected, the shape and size of the defect, the depth of burial, etc.: When the other conditions are the same, the magnetic flux generated by the pores buried in the same depth at the surface is smaller than the leakage flux generated by the transverse crack.
9. Why do some parts need to be demagnetized after magnetic particle inspection?
A: The remanence of some rotating parts will attract iron scraps and cause frictional damage to the parts during rotation, such as shaft bearings. The remanence of some parts will cause nearby instruments to indicate anomalies. So why do some parts need to be demagnetized after magnetic particle inspection?
X. What are the basic principles of ultrasonic flaw detection?
A: Ultrasonic flaw detection is a method that uses ultrasonic energy to penetrate into the depths of metallic materials, and when a section enters another section, reflection occurs at the edge of the interface to check the defect of the part. When the ultrasonic beam passes from the surface of the part, the probe When it reaches the inside of the metal, the reflected wave occurs when the defect and the bottom of the part are encountered. The pulse waveform is formed on the fluorescent screen, and the position and size of the defect are judged based on these pulse waveforms.
11. What are the disadvantages of ultrasonic flaw detection and X-ray inspection?
A: Ultrasonic inspection has higher detection sensitivity, shorter cycle time, lower cost, flexibility, convenience, higher efficiency, and less harm to the human body than X-ray inspection. The disadvantage is that inspection personnel who require smooth working surfaces and require extensive experience can discern. The type of defect is not intuitive to the defect; ultrasonic flaw detection is suitable for inspection of parts with larger thickness.
12. What are the main features of ultrasonic testing?
Answer: 1. When ultrasonic waves propagate in the medium, they have the characteristics of reflection at different quality interfaces. If defects are encountered and the size of the defects is equal to or greater than the wavelength of the ultrasonic waves, then the ultrasonic waves reflect back on the defects. The flaw detector can reflect the waves. Shown; if the size of the defect is even smaller than the wavelength, the acoustic wave will bypass the beam and cannot reflect;
2. The directionality of the wave sound is good. The higher the frequency is, the better the directionality is, and the narrow beam is radiated into the medium, so it is easy to determine the position of the defect.
3, ultrasonic transmission of energy, such as the frequency of 1MHZ (100Hz) of the ultrasound wave propagation of energy, equivalent to the same amplitude and frequency of 1000HZ (Hertz) of the sound wave 1000000 times.
XIII. What is the relationship between the three main curves on the amplitude curve when the thickness of the ultrasonic wave is 14 mm?
A: Measuring length Ф 1 х 6 -12dB
Quantitative line Ф 1 х 6 -6dB
Criteria Line Ф 1 х 6 -2dB
14. What are the "soft" and "hard" rays?
A: The ability of X-rays to penetrate matter is related to the wavelength of the ray itself. The shorter the wavelength (the higher the tube voltage), the greater the penetration ability, which is called “hardâ€; otherwise it is called “softâ€.
15. What are the causes of the disappearance of the bottom wave when using ultrasonography?
A: 1, large defects near the table; 2, absorptive defects; 3, tilt large defects; 4, the combination of oxide and steel is not good.
16. What are the main factors affecting the development?
A: 1, the development time; 2, the developer temperature; 3, the shaking of the developer; 4, formula type; 5, the degree of aging.
17. What is current?
A: Current refers to a regular movement of an electron under a certain direction of external force. In the direction of current, it is customary to specify that the positive electrode of a power source flows through the power device to the negative electrode in a positive direction, that is, in the opposite direction to the electron.
18. What is the current intensity?
A: The current intensity is the amount of electricity that passes through the cross section of the conductor per unit time. The current is also sometimes referred to as the current intensity. It can be written as I = Q \ T where I is the current strength Q is the quantity of electricity, and T is the time.
Nineteenth, what is resistance?
A: Refers to the resistance of the current flowing in the conductor. At the same temperature, the resistances of different substances with the same length and cross-sectional area are often very different; the resistance is represented by "R" and the unit is ohm, abbreviated as European. Expressed in Ω.
20. What is voltage?
Answer: In the role of the power supply, the positive and negative charges inside the conductor are pushed to the two ends of the conductor to make it have a potential difference. The unit of the voltage is volts, and is referred to as “V†for short.
21. What are the characteristics of AC power?
A: The current, voltage, and potential of AC circuits are not constant, but they are alternating. They are characterized by the periodic changes in the magnitude and direction of currents, voltages, and potentials; industrial and mining companies. The AC motors used in the equipment, civil lighting, and electrical appliances for daily life are all AC power; AC power is divided into three phases and single phases, with voltages of 380 volts and 220 volts.
Twenty-two, what is the direct current, what are the characteristics?
Answer: At any moment, the current through the cross section of the conductor is equal and the direction is constant at any time. Its characteristic is that the current, voltage and potential of the circuit do not change with time. But constant; DC motor, electroplating, motor excitation, battery charging, and semiconductor circuits.
What is Ohm's Law?
A: Ohm's law reflects the relationship between resistance, voltage, and current in a circuit through which a steady current flows. Ohm's law states that the current in a circuit is proportional to the voltage across the circuit and is inversely proportional to the resistance in the circuit; that is, I = V \ R.
Twenty-four. What is electromagnetic induction?
A: The magnetic flux changes through the closed loop, and the phenomenon of generating electromotive force in the loop is called electromagnetic induction. This produces an electromotive force called induced electromotive force. If the conductor is a closed loop, current will flow through it. The current is called induced current. Transformers, generators, and various inductors are all based on the principle of electromagnetic induction.
25. What is the reason for the attenuation caused by the passage of ultrasound waves in media in the detection of ultrasound waves?
Answer: 1. The diffusion propagation distance of the ultrasonic wave increases, the beam cross-section becomes larger, and the energy per unit area decreases.
2. The material attenuation is the absorption caused by the viscosity of the medium; the second is the scattering caused by the disordered reflection at the interface of the medium.
26. What is the main role of the CSK-IIA test block?
A: 1, calibration sensitivity; 2, calibration scan linear.
27. What are the main factors affecting photographic sensitivity?
A: 1, X-ray machine's focus size; 2, the choice of transillumination parameters is reasonable, the main parameters of the tube voltage, tube current, exposure time and focal length size; 3, sensitization mode; 4, the choice of film is reasonable; 5, dark room processing conditions; 6, scattering shielding and so on.
Twenty-eight, using ultrasonic waves to inspect the large forgings of cakes. If using the bottom wave to adjust the initial sensitivity of flaw detection, what are the requirements for the bottom of the work?
Answer: 1. The bottom surface must be parallel to the flaw surface;
2, the bottom must be flat and have a certain degree of finish.
Twenty-nine, ultrasonic flaw detection chooses the probe K value which three principle?
Answer: 1. The sound beam scans the entire weld section;
2, the sound beam as far as possible perpendicular to the main defect;
3, there is enough sensitivity.
30. What are the major components of the ultrasonic flaw detector?
Answer: It mainly consists of circuit synchronization circuit, generation circuit, receiving circuit, horizontal scanning circuit, display and power supply.
31. What is the main role of the transmitter circuit?
Answer: The synchronization pulse signal input by the synchronizing circuit triggers the operation of the transmission circuit to generate a high-frequency electric pulse signal to excite the wafer, generate high-frequency vibration, and generate ultrasonic waves in the medium.
32. What are the reasons for the use of a couplant between the wafer surface and the surface of the probed workpiece during ultrasonic flaw detection?
A: The air gap between the surface of the wafer and the surface of the workpiece being inspected will cause the ultrasonic wave to completely reflect, causing flaw detection results to be inaccurate and undetectable.
Thirty-three, what are the three conditions for discriminating defects as defined in the JB1150-73 standard?
Answer: 1. There are only multiple flaws in the reflection wave.
2. There are only a few turbulent defect waves in bottomless waves.
3. Defective waves and bottom waves exist at the same time.
34. What is the purpose of the distance specified in the JB1150-73 standard?
Answer: The distance-amplitude curve is mainly used to determine the size of defects and provide basis for the acceptance criteria. It is composed of three lines: the discarded line, the quantitative line, and the long line.
Judging the waste line - the maximum allowable equivalent to determine the defect;
Quantitative line - the control line for determining the size and length of the defect; the long line - the detection start sensitivity control line.
35. What is an ultrasound field?
A: The space filled with the energy of the ultrasound field is called an ultrasound field.
36. What are the main parameters reflecting the characteristics of the ultrasound field?
A: The important physical quantities that reflect the characteristics of the ultrasonic field include sound intensity, acoustic pressure acoustic impedance, sound beam propagation angle, near field and far field areas.
37. What are the most important performance indicators for flaw detectors?
A: Resolution, dynamic range, horizontal linearity, vertical linearity, sensitivity, signal-to-noise ratio.
38. How can the ultrasonic flaw detector be displayed in several ways?
A: 1. A-type display oscilloscope screen represents the ultrasonic transmission time (or distance) ordinate represents the height of the reflected echo; 2, B-type display oscilloscope horizontal coordinates represent the time (or distance) of ultrasonic transmission broadcast. This type of display gives a cross-sectional view of the depth direction of the probe scanning; 3. The C-type display instrument oscilloscope represents the projection surface of the workpiece to be inspected. This display can plot the horizontal projection position of the defect, but it cannot give a defect. The depth of burial.
39. What is the main role of ultrasonic probes?
Answer: 1. The probe is an electro-acoustic transducer and can convert the returned sound waves into electric pulses; 2. Control the propagation direction of the ultrasonic wave and the degree of energy concentration, when changing the incident angle of the probe or changing the diffusion angle of the ultrasonic wave , The main energy of the sound wave can be injected into the media at different angles or change the directivity of the sound wave, improve the resolution; 3, to achieve the wave mode conversion; 4, control the operating frequency; applicable to different working conditions.
Forty, magnetic particle probe safety operation requirements?
A: 1, when the workpiece directly through the electromagnetic, it should pay attention to the poor contact between the chuck, or use too much magnetization current caused arc flash, should wear protective glasses, and should not be used in the occasion of possible gas 2, in the continuous use of wet magnetic suspension, the skin can be coated with protective cream; 3, such as for magnetic suspension, the equipment must be well grounded to prevent electric shock; 4, in the use of magnetic powder when the flame, the use of ultraviolet rays Filters must be used to protect the eyes and skin.
Forty-one, what is the resolution?
A: The minimum distance between images that can be identified on a radiography film or screen, usually expressed as the number of recognizable lines per 1 mm.
Forty-two, what is geometric uncertainty?
A: The unsharpness and penumbra caused by the penumbra depend on the focus size, focal length and workpiece thickness.
Forty-three, why should we strengthen the super wave detection and recording and reporting work?
Answer: After any work piece has undergone ultrasonic flaw detection, it must issue inspection reports as proof of the quality of the work. A correct inspection report, in addition to establishing reliable detection methods and results, depends largely on the original records. The final inspection report is very important. If we check the workpiece without recording or report, the inspection will be meaningless.
44. Why use sensitive test strips in magnetic particle inspection?
Answer: The purpose of using sensitive test strips is to examine the properties of magnetic powders and magnetic suspensions and to determine the effective magnetic field strength and direction of the test pieces and the correctness of the operation methods in the continuous method.
Forty-five, what is the fixing effect?
A: After developing the film in the shadow solution, the shadowing agent dissolves the undeveloped silver bromide above it, and the process of protecting the ferrous silver particles is called fixing.
What is the basic principle of coloring (permeation) flaw detection?
A: The basic principle of coloring (permeation) flaw detection is to use capillary phenomenon to make the permeation fluid penetrate into the defect, and the surface permeation fluid is removed after washing, and the residual tumor in the defect is recovered, and the residual defect is absorbed by the capillary action of the imaging agent. Tumor infiltrate to achieve the purpose of testing defects.
Forty-seven, coloring (permeation) detection of the main factors of sensitivity?
Answer: 1. The influence of the performance of the penetrant; 2. The emulsification effect of the emulsifier; 3. The influence of the performance of the developer; 4. The influence of the operation method; 5. The influence of the nature of the defect.
48. How to classify defects in welds in ultrasonic flaw detection?
Answer: In the ultrasonic inspection of welds, the defects in welds are generally divided into three types: point defects, line defects, and surface defects.
In the classification, a defect with a length of less than 10 mm is called a punctiform defect; generally, the length is not measured, and a defect smaller than 10 mm is counted as 5 mm. Defects greater than 10 mm in length are called linear defects. Defects greater than 3 mm in length greater than 10 mm are called surface defects.
Forty-nine, how about the film flushing process?
A: Develop, stop, fix, wash, dry.
Fifty, what is the conductivity?
A: The nature of the metal's ability to conduct electrical current.
51, what is magnetic?
A: refers to the metal has magnetic properties; from a practical point of view such as: magnetic materials (metal) can be used to make permanent magnets, electrical materials, but also can be used to check the magnetic metal magnetic cracks
52. What is high pressure?
A: The device voltage is more than 250 volts is called high voltage.
Fifty-three, what is low pressure?
A: The device voltage to ground below 250 volts is called low voltage.
54. What is the safe voltage?
Answer: When a person touches an electrified conductor, there is no life-threatening voltage. In general, a voltage of less than 36 volts is called a safety voltage.
Wherever the workplace is wet or in metal containers, electrical lighting in tunnels, mines, etc., 12 volt safety voltage is used.
Fifty-five, what is the role of ultrasonic test block?
A: The function of the ultrasonic test block is to verify the performance of the instrument and the probe, determine the initial detection sensitivity, and calibrate the scan linearity.
Fifty-six, what is the correct value of the angle of refraction of the oblique probe?
Answer: The correct value of the refraction angle of the oblique probe is called the K value, which is equal to the ratio of the horizontal distance and the corresponding depth of the oblique probe λ shot point to the reflection point.
Fifty-seven, when the local non-destructive inspection welds found in the weld imperfections how to do?
Answer: A supplementary ray inspection should be performed in the direction of the defect or at the suspicious part. After the supplementary inspection, there are still doubts about the quality of the weld. All welds should be flawed.
58. What are the magnetic flaws caused by non-defects?
A: 1, local cold hardening, magnetic mark caused by the magnetic material changes caused by the accumulation; 2, two different materials at the interface of the magnetic powder accumulation; 3, carbide layer segregation; 4, part of the cross-sectional size of the mutation at the magnetic Trace; 5, the magnetization current is too high, due to the metal streamline caused by the magnetic mark; 6, due to the workpiece surface is not clean or oil stains caused by the spot-like magnetic marks.
59. What are the contents of magnetic particle inspection procedures?
Answer: 1, the scope of application of the procedure; 2, magnetization method (including magnetization specification, the preparation of the workpiece surface); 3, magnetic powder (including particle size, color, magnetic suspension and fluorescent magnetic suspension preparation). 4, test piece; 5, technical operation; 6, quality assessment and inspection records.
Sixty, magnetic particle detection scope?
A: Magnetic particle inspection is a kind of detection method used to detect the surface and near surface defects of ferromagnetic materials.
61. What is the main role of the synchronization signal generator in the ultrasonic flaw detector? Which two parts of the circuit do you mainly control?
A: The synchronization circuit generates a synchronization pulse signal to trigger the simultaneous coordination of the various parts of the instrument circuit. It mainly controls the synchronous emission and synchronous scanning of the two parts of the circuit.
Sixty-two, the purpose of non-destructive testing?
Answer: 1, improve the manufacturing process; 2, reduce manufacturing costs; 3, improve product possibilities; 4, to ensure the safe operation of equipment.
Sixty-three, ultrasonic welding flaw detection device for the defect positioning time scan line adjustment of several ways?
A: There are three methods: horizontal locator, vertical positioning, and sound path positioning.
Sixty-four, try to compare the main advantages and disadvantages of the dry powder method and wet powder method test?
Answer: The dry powder method has high detection capability for near-surface defects, and is particularly suitable for large area or field inspections. The wet powder method has high detection capability for small surface defects, and is particularly suitable for batch inspection of small parts with irregular shapes.