Split-type LIBS (laser-induced breakdown spectroscopy) aluminum alloy sensitization degree field detection device and method

Abstract

The invention provides a split type LIBS aluminum alloy sensitization degree on-site detection device and method, and relates to the technical field of laser spectrum analys.The split type LIBS aluminum alloy sensitization degree on-site detection device comprises a pulse generation module and a sample detection module, the pulse generation module is connected with the sample detection module through a corrugated pipe, and an energy transmission optical fiber, an LIBS signal optical fiber, a power source and a communication line are all connected with the pulse generation module; the energy transmission optical fiber transmits the high-energy excitation pulse to the long-wave-pass dichroscope, the high-energy excitation pulse is focused to the to-be-detected alloy, and an LIBS signal generated by exciting the to-be-detected alloy by the high-energy excitation pulse is reflected to the reflective optical fiber collimator through the long-wave-pass dichroscope and is transmitted to the pulse generation module through the LIBS signal optical fiber; the second optical fiber collimator, the reflector, the first lens, the second lens, the long-wave-pass dichroscope, the three-wavelength objective lens and the reflective optical fiber collimator are arranged on the light path debugging frame, and the light path debugging frame and the high-precision motion table are installed on the bottom plate. According to the invention, the accuracy and reliability of alloy sensitization degree evaluation can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser spectrum analysis, and particularly relates to a split type LIBS aluminum alloy sensitization degree on-site detection device and method. BACKGROUND

[0002] Laser-induced breakdown spectroscopy (LIBS) is a technology based on the interaction of laser and matter to generate transient plasma, and the elements are qualitatively or quantitatively analyzed by analyzing the spectrum emitted by the plasma. LIBS has the advantages of non-destructive, fast, sensitive, etc., and can analyze elements of various materials without complex sample preparation. LIBS has been applied to the composition analysis and corrosion detection of aluminum alloy, but its application in the detection of aluminum alloy sensitization degree still faces certain challenges.

[0003] A fiber array LIBS detection system for online detection is disclosed in Chinese Patent No. CN112730383B, which comprises a laser fiber coupling module, a laser control module and a spectrum acquisition module. The laser fiber coupling module comprises a nanosecond laser, a dichroic mirror, a plano-convex lens and a transmission optical fiber. The laser control module comprises a beam splitter, a beam splitter, a photodiode, a laser energy meter and a programmable pulse delay generator. The spectrum acquisition module comprises a plano-convex lens, a collection optical fiber, a spectrometer and an ICCD. The laser beam emitted from the nanosecond laser finally enters the fiber array LIBS probe through the transmission optical fiber. The fiber array module is installed directly above the equipment to be detected, and the 16 fiber sleeves on it can realize synchronous detection of the two-dimensional array of the entire equipment surface. However, the above-mentioned scheme mainly relies on the fiber array and only uses a single plano-convex lens for focusing, and the laser spot size and collection efficiency are limited, and are easily disturbed by external environmental factors such as air pressure and humidity, resulting in unstable spectral signals. Therefore, it is necessary to provide a split type LIBS aluminum alloy sensitization degree on-site detection device and method to improve the accuracy and reliability of alloy sensitization degree evaluation. SUMMARY

[0004] Therefore, the present application provides a split type LIBS aluminum alloy sensitization degree on-site detection device and method. Laser ranging and three sets of precision threaded pairs are used to realize structural leveling, ensuring that the laser is always focused vertically on the surface of the sample to be measured. The real-time acquisition and feedback of temperature, humidity and air pressure parameters are introduced to enhance the modeling accuracy under complex working conditions. The use of multi-point adsorption and split structure improves the deployment efficiency of the device on irregular surfaces. The overall optical path and mechanical structure of the device are optimized for aluminum alloy organization and sensitization characteristics, enabling high-sensitivity detection of trace element precipitation and phase change state, and improving the accuracy and reliability of alloy sensitization degree evaluation.

[0005] The application provides a split type LIBS aluminum alloy sensitization degree on-site detection device, which comprises a pulse generation module and a sample detection module, wherein, The pulse generation module is connected with the sample detection module, and is used for generating a high-energy excitation pulse and receiving LIBS spectrum data sent by the sample detection module. The sample detection module comprises an energy transmission optical fiber, a second optical fiber collimator, a reflector, a first lens, a second lens, a long-wave pass dichroic mirror, a three-wavelength objective lens, a reflective optical fiber collimator, a LIBS signal optical fiber, a high-precision motion table, a power supply and communication line, a precision threaded pair and a bottom plate; the energy transmission optical fiber, the LIBS signal optical fiber and the power supply and communication line are connected with the pulse generation module; the high-energy excitation pulse is transmitted to the long-wave pass dichroic mirror through the second optical fiber collimator, the reflector, the first lens and the second lens in sequence; the high-energy excitation pulse is focused to the alloy to be measured through the long-wave pass dichroic mirror and the three-wavelength objective lens in sequence; the LIBS signal generated by the alloy to be measured excited by the high-energy excitation pulse is reflected to the reflective optical fiber collimator through the long-wave pass dichroic mirror, and is transmitted to the pulse generation module through the LIBS signal optical fiber. The second optical fiber collimator, the reflector, the first lens, the second lens, the long-wave pass dichroic mirror, the three-wavelength objective lens and the reflective optical fiber collimator are arranged on a light path debugging rack; the light path debugging rack and the high-precision motion table are installed on the bottom plate; the high-precision motion table is connected with the pulse generation module through the power supply and communication line to transmit information; and the high-precision motion table is used for adjusting the vertical distance between the objective lens plane and the surface of the alloy to be measured.

[0006] On the basis of the above technical scheme, preferably, the sample detection module further comprises a laser range finder, a ranging optical fiber, a sensing unit and a USB line; the laser range finder and the sensing unit are arranged on the light path debugging rack; the laser range finder is connected with the pulse generation module through the ranging optical fiber; the laser range finder is used for measuring the distance between the three-wavelength objective lens and the surface of the alloy to be measured; the sensing unit is connected with the pulse generation module through the USB line; and the sensing unit is used for measuring the temperature, humidity and air pressure around the three-wavelength objective lens.

[0007] On the basis of the above technical scheme, preferably, the pulse generation module comprises a nanosecond pulse laser, a beam expander and a first optical fiber collimator arranged on the light path of the nanosecond pulse laser, a comprehensive processing mainboard, a signal delay generator, a micro optical fiber spectrometer and a control system, wherein, The first optical fiber collimator is connected with the sample detection module through the energy transmission optical fiber, the integrated processing mainboard is connected with the nanosecond pulse laser, the signal delay generator, the micro fiber spectrometer and the control system respectively, the signal delay generator is connected with the nanosecond pulse laser and the micro fiber spectrometer respectively, the micro fiber spectrometer is electrically connected with the sample detection module through the LIBS signal optical fiber, the control system is connected with the signal delay generator, and the control system is connected with the sample detection module through the ranging optical fiber, the USB line and the power supply and communication line respectively.

[0008] Further preferably, the sample detection module further comprises three sets of precision threaded pairs, the high-precision motion table is fixed on the bottom plate by the three sets of precision threaded pairs, the three sets of precision threaded pairs are distributed at the three top corners of the high-precision motion table, the three sets of precision threaded pairs are connected to form a right triangle, and the precision threaded pairs at the right angle points are used as fixed points, and the remaining precision threaded pairs are used as adjustment points to adjust the pitch angle and the deflection angle of the high-precision motion table, so as to adjust the parallelism between the three-wavelength objective lens and the surface of the alloy to be measured, and at the same time, the high-precision motion table adjusts the Z-axis position of the three-wavelength objective lens, so that the distance between the surface of the alloy to be measured and the three-wavelength objective lens is constant.

[0009] Further preferably, the sample detection module further comprises a plurality of suction cups, and the suction cups are arranged on the side of the bottom plate away from the high-precision motion table.

[0010] Further preferably, the long-wave pass dichroic mirror has high transmittance in a wavelength band greater than or equal to 420 nm and high reflectivity in a wavelength band less than 420 nm, the reflectivity of the long-wave pass dichroic mirror in the wavelength band less than 420 nm is higher than 90%, and the transmittance of the long-wave pass dichroic mirror in the wavelength band of 420 nm to 1100 nm is higher than 95%.

[0011] Further preferably, the three-wavelength objective lens has high transmittance in the 2nd harmonic wave band of YAG, the 3rd harmonic wave band of YAG and the 4th harmonic wave band.

[0012] Further preferably, the output wavelength of the nanosecond pulse laser is 532 nm, the pulse width of the nanosecond pulse laser is less than 10 ns, the repetition frequency of the nanosecond pulse laser is 1-100 Hz, the wavelength range of the micro fiber spectrometer is 270 nm-410 nm, and the spectral line resolution of the micro fiber spectrometer is higher than 0.1 nm.

[0013] More preferably, the power transmission fiber, the LIBS signal fiber, the ranging fiber, the USB cable, and the power and communication lines are all disposed inside the corrugated tube, and the pulse generation module and the sample detection module are connected through the corrugated tube.

[0014] A second aspect of this application provides a method for on-site detection of sensitization of split-type LIBS aluminum alloys, the method comprising: Configure and preheat the nanosecond pulse laser in the pulse generation module; The sample detection module is attached to the surface of the metal to be tested. The high-precision motion stage in the sample detection module, together with the laser rangefinder, detects the parallelism between the test area of ​​the metal to be tested and the three-wavelength objective lens, and adjusts the pitch of the high-precision motion stage on the X and Y axes according to the decoupling algorithm. The high-precision motion stage is used in conjunction with the laser rangefinder to perform surface shape fitting on the area to be measured. Based on the surface shape fitting result, the Z-axis position of the three-wavelength objective lens is adjusted by the high-precision motion stage. When the distance between the three-wavelength objective lens and the metal to be measured is less than or equal to a preset distance, the nanosecond pulse laser is triggered to generate a high-energy excitation pulse, and the LIBS signal, temperature, humidity and air pressure of the metal to be measured after excitation are collected. The high-precision motion stage is moved to the next test area according to the preset path, the nanosecond pulse laser is triggered again to generate a high-energy excitation pulse, and the LIBS signal of the corresponding area is collected. The measurement process is repeated until the collected LIBS signal meets the spectral quantity threshold. Based on the spectral data, temperature, humidity, and air pressure in each LIBS signal, a quantitative model for the sensitization degree of aluminum alloy is constructed. The real-time LIBS signal is then input into the quantitative model for the sensitization degree of aluminum alloy to obtain the alloy sensitization degree.

[0015] The split-type LIBS aluminum alloy sensitization field testing device and method provided by this invention have the following advantages over the prior art: (1) The high-energy excitation pulse and the LIBS signal optical path are precisely separated by a long-pass dichroic mirror, which not only ensures the high transmittance of the excitation light but also avoids interference in the signal path and improves the signal-to-noise ratio. The second fiber collimator, mirror, double lens, three-wavelength objective lens and reflective fiber collimator are integrated on the optical path adjustment frame. With the help of a high-precision motion stage, the vertical distance between the objective lens plane and the sample plane can be precisely adjusted to ensure the focusing accuracy of the excitation light and the signal collection efficiency, and to achieve reproducible optical path alignment. At the same time, a specially designed LIBS signal fiber and reflective collimator are used to effectively receive the weak spectral signal generated after the alloy under test is excited and transmit it back to the pulse generation module for real-time analysis. Furthermore, the overall optical path and mechanical structure of the device are optimized for the microstructure and sensitization characteristics of aluminum alloy, which can achieve high sensitivity detection of trace element precipitation and phase transition state, and improve the accuracy and reliability of the sensitization degree assessment of aluminum alloy. Through the electrical separation of the pulse generation module and the sample detection module, the whole machine is small in size and light in weight, which is convenient for on-site carrying and rapid deployment.

[0016] (2) A mechanical leveling mechanism is constructed by a laser rangefinder and three sets of precision threaded pairs to realize the adjustment of the pitch and deflection angle of the objective lens. Combined with the height adjustment in the Z-axis direction, it can realize the vertical focusing of laser on concave, convex, tilted or non-planar metal surfaces, effectively improving the consistency of excitation position and plasma stability. Furthermore, the preset path movement and triggering logic can automatically cycle and collect LIBS signals in multiple areas, avoiding manual handling and repeated focusing.

[0017] (3) The detection device is equipped with an environmental parameter sensing unit, which can collect temperature, humidity and air pressure information in real time and use it as input to participate in subsequent quantitative model calculations. This effectively eliminates the influence of external condition fluctuations on the spectral signal, enhances the consistency and accuracy of the measurement, and the modular design combined with the automated measurement process makes it quick to deploy and easy to operate, greatly shortening the detection cycle. It is suitable for the inspection of aluminum alloy parts with large area structure or multi-point layout. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the frame of a split-type LIBS aluminum alloy sensitization field testing device provided by the present invention; Figure 2 A schematic diagram illustrating the adjustment principle of the three sets of precision threaded pairs provided by this invention; Figure 3 This invention provides a schematic diagram of the motion path. Figure 4 The LIBS spectrum provided by this invention; Figure 5 A comparison chart of the detection results provided by this invention and the results of the nitric acid mass loss method.

[0020] Explanation of reference numerals in the attached figures: 1. Nanosecond pulse laser; 2. Beam expander group; 3. First fiber collimator; 4. Integrated processing motherboard; 5. Signal delay generator; 6. Miniature fiber optic spectrometer; 7. Control system; 8. Corrugated tube; 9. Power transmission fiber; 10. Second fiber collimator; 11. Reflector; 12. First lens; 13. Second lens; 14. Long-pass dichroic mirror; 15. Three-wavelength objective lens; 16. Reflective fiber collimator; 17. LIBS signal fiber; 18. Laser rangefinder; 19. Ranging fiber; 20. Sensing unit; 21. USB cable; 22. High-precision motion stage; 23. Power and communication line; 24. Precision threaded pair; 25. Base plate; 26. Suction cup; 27. Probe housing; 28. Chassis housing; 29. ​​Chassis casters; 30. Alloy under test. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "connected" or "linked" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up," "down," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0023] refer to Figure 1 This invention provides a split-type LIBS aluminum alloy sensitization field testing device, comprising a pulse generation module and a sample detection module, wherein... The pulse generation module is connected to the sample detection module. The pulse generation module is used to generate high-energy excitation pulses and receive LIBS spectral data sent by the sample detection module.

[0024] In this embodiment, the pulse generation module includes a nanosecond pulse laser 1, a beam expander group 2 and a first fiber collimator 3 disposed on the light output path of the nanosecond pulse laser 1, a main processing board 4, a signal delay generator 5, a miniature fiber optic spectrometer 6, and a control system 7. The first fiber collimator 3 is connected to the sample detection module through a power transmission fiber 9. The main processing board 4 is connected to the nanosecond pulse laser 1, the signal delay generator 5, the miniature fiber optic spectrometer 6, and the control system 7. The signal delay generator 5 is connected to the nanosecond pulse laser 1 and the miniature fiber optic spectrometer 6. The miniature fiber optic spectrometer 6 is electrically connected to the sample detection module through a LIBS signal fiber 17. The control system 7 is connected to the signal delay generator 5. The control system 7 is connected to the sample detection module through a ranging fiber 19, a USB cable 21, and a power and communication cable 23. The output wavelength of the nanosecond pulse laser 1 is 532nm, the pulse width of the nanosecond pulse laser 1 is less than 10ns, the repetition frequency of the nanosecond pulse laser 1 is 1-100Hz, the wavelength range of the miniature fiber optic spectrometer 6 is 270nm-410nm, and the spectral resolution of the miniature fiber optic spectrometer 6 is higher than 0.1nm.

[0025] Furthermore, the nanosecond pulse laser 1 is used to provide a 532nm high-energy excitation pulse. The beam expander group 2 is used to expand the laser beam multiple times, improving coupling efficiency and alignment accuracy. The first fiber collimator 3 is used to couple the 532nm high-energy excitation pulse into the energy transfer fiber 9. The integrated processing motherboard 4 primarily functions as the main control board, controlling all other instrument components, including the laser. It also houses a pre-trained neural network model that can receive and process data from the miniature spectrometer. The signal delay generator 5 is used to achieve timing control between the excitation pulse beam and the data acquired by the miniature fiber optic spectrometer 6, avoiding bremsstrahlung background noise generated during the initial LIBS acquisition by the miniature fiber optic spectrometer 6, achieving a time resolution better than 1ns. The miniature fiber optic spectrometer 6 acquires LIBS spectral data and transmits the spectral information back to the integrated processing motherboard 4. The control system 7 integrates multiple controllers to achieve different functions. According to the program set by the integrated processing motherboard 4, it controls the high-precision motion stage 22 to achieve the given motion trajectory and sends a high-level trigger signal when the high-precision motion stage 22 moves to the preset position; it is used to read the return signal of the laser rangefinder 18 to obtain the distance information between the probe and the surface to be measured, and uses this information to adjust the Z-axis position of the probe part; it is used to read the temperature, humidity and air pressure information measured by the sensor; and it is used to control whether the suction cup 26 is adsorbed.

[0026] The sample detection module includes an energy transmission fiber 9, a second fiber collimator 10, a reflector 11, a first lens 12, a second lens 13, a long-pass dichroic mirror 14, a three-wavelength objective lens 15, a reflective fiber collimator 16, a LIBS signal fiber 17, a high-precision motion stage 22, a power and communication line 23, a precision threaded pair 24, and a base plate 25. The energy transmission fiber 9, the LIBS signal fiber 17, and the power and communication line 23 are all connected to the pulse generation module. The energy transmission fiber 9 transmits the high-energy excitation pulse sequentially through the second fiber collimator 10, the reflector 11, the first lens 12, and the second lens 13 to the long-pass dichroic mirror 14. The high-energy excitation pulse is then focused onto the alloy 30 under test by the long-pass dichroic mirror 14 and the three-wavelength objective lens 15. The LIBS signal generated by the high-energy excitation pulse on the alloy 30 under test is reflected by the long-pass dichroic mirror 14 to the reflective fiber collimator 16 and transmitted to the pulse generation module through the LIBS signal fiber 17.

[0027] The sample detection module also includes a laser rangefinder 18, a ranging fiber optic cable 19, a sensing unit 20, and a USB cable 21. Both the laser rangefinder 18 and the sensing unit 20 are mounted on the optical path debugging rack. The laser rangefinder 18 is connected to the pulse generation module through the ranging fiber optic cable 19. The laser rangefinder 18 is used to measure the distance between the three-wavelength objective lens 15 and the surface of the alloy 30 under test. The sensing unit 20 is connected to the pulse generation module through the USB cable 21. The sensing unit 20 is used to measure the temperature, humidity, and air pressure around the three-wavelength objective lens 15.

[0028] The second fiber collimator 10, the reflector 11, the first lens 12, the second lens 13, the long-pass dichroic mirror 14, the three-wavelength objective lens 15, and the reflective fiber collimator 16 are all mounted on the optical path adjustment frame. The optical path adjustment frame and the high-precision motion stage 22 are both mounted on the base plate 25. The high-precision motion stage 22 transmits information to the pulse generation module through the power supply and communication line 23. The high-precision motion stage 22 is used to adjust the vertical distance between the objective lens plane and the surface to be measured.

[0029] In one example, the second fiber collimator 10, the reflector 11, the plano-concave lens, the plano-convex lens, the long-pass dichroic mirror 14, the three-wavelength objective lens 15, and the reflective fiber collimator 16 constitute a complete optical system. The plano-convex lens and the plano-concave lens constitute a beam expanding system, so that the diameter of the laser beam matches the entrance pupil of the objective lens, resulting in a smaller focused spot. The long-pass dichroic mirror 14 has a cutoff wavelength of 420nm, so that LIBS signals with wavelengths below 420nm are reflected, while high-energy excitation pulses with wavelengths above 500nm are transmitted. The three-wavelength objective lens 15 preferably has high transmittance in the three bands of YAG: the second harmonic (532nm), the third harmonic (355nm), or the fourth harmonic (266nm). The reflective fiber collimator 16 is preferably of the ultraviolet-enhanced type. The optical axis of the fiber collimator is set at 45° to the reflector 11, and the axes of the reflector 11, the plano-concave lens, the plano-convex lens, the long-pass dichroic mirror 14, and the three-wavelength objective lens 15 are located on the same straight line.

[0030] The laser rangefinder 18 is preferably a spectral confocal rangefinder, with a ranging accuracy better than 0.6μm and a ranging range greater than 3mm. The high-precision motion stage 22 employs a 3-axis motion mechanism, which carries an optical path module for dynamic scanning; it uses a stepper motor and grating ruler structure, with a C3-grade lead screw directly connected to the motor, achieving a repeatability accuracy better than 1μm; it uses a high-rigidity crossed roller guide, with a P-grade accuracy and straightness better than 1μm. The supporting adsorption and leveling unit includes a base plate 25, a suction cup 26, and a precision threaded pair 24. Three sets of ejector pins are designed under the base plate 25 as a rigid support structure, which can accommodate various uneven test surfaces. A vacuum ring is fixed around the ejector pins, and an annular air channel is designed inside. Vacuum suction cups 26 are evenly distributed under the air channel. An air extraction port is opened at a certain point of the annular air channel and a quick-change connector is installed. After connecting the air pipe and vacuum pump, negative pressure is generated, which can be adsorbed on horizontal, inclined and vertical surfaces. Three sets of precision threaded pairs 24 are fixed to the top of the high-precision motion stage 22 with copper sleeves. The inner ring is a precision thread. Deep groove ball bearings are installed on the base plate 25. After the bottom of the adjusting screw passes through the bearing, it is locked by the scale and nut. The adjustment is better than 15 mrad per revolution of the threaded pair.

[0031] like Figure 2As shown, the sample detection module also includes three sets of precision threaded pairs 24. The high-precision motion stage 22 is fixed to the base plate 25 by the three sets of precision threaded pairs 24. The three sets of precision threaded pairs 24 are distributed at the three apex corners of the high-precision motion stage 22. The shape formed by the connection of the three sets of precision threaded pairs 24 is a right-angled triangle. The precision threaded pair 24 located at the right angle point serves as a fixed point, and the remaining precision threaded pairs 24 serve as adjustment points. The pitch angle and deflection angle of the high-precision motion stage 22 are adjusted to adjust the parallelism between the three-wavelength objective lens 15 and the surface of the alloy 30 under test. At the same time, the high-precision motion stage 22 adjusts the Z-axis position of the three-wavelength objective lens 15, so that the distance between the surface of the alloy 30 under test and the three-wavelength objective lens 15 is constant, and the distance error between the surface of the alloy 30 under test and the three-wavelength objective lens 15 is less than 2μm. The sample detection module also includes multiple suction cups 26, which are set on the side of the base plate 25 opposite to the high-precision motion stage 22.

[0032] Furthermore, the power transmission fiber 9 is used to transmit the output of the nanosecond pulse laser 1 to the probe section, the second fiber collimator 10 is used to collimate the laser output from the power transmission fiber 9, and the reflector 11 is used to fold the optical path by 90°, making the probe structure more compact. The first lens 12 and the second lens 13 form a Galilean beam expander group 2, which is used to expand the laser beam multiple times, so that the laser beam diameter matches the entrance pupil of the objective lens and obtains a smaller focused spot. The long-pass dichroic mirror 14 is used to separate the high-energy excitation pulse and the LIBS signal. The cutoff wavelength is selected at 420nm. The LIBS signal with a wavelength below 420nm is reflected, and the high-energy excitation pulse with a wavelength above 500nm is transmitted. The three-wavelength objective lens 15 is used to focus the 532nm high-energy excitation pulse, and at the same time collect the light of the 280-400nm laser-induced breakdown spectral component into the probe at the rear end. A reflective fiber collimator 16 is used to couple the 280-400nm signal light from the laser-induced breakdown spectrum into the LIBS signal fiber 17. Due to its achromatic properties, it can achieve high-efficiency coupling across a wide wavelength range. The LIBS signal fiber 17 is used to transmit the LIBS signal to the miniature fiber optic spectrometer 6 inside the chassis. A laser rangefinder 18 is used to measure the distance between the probe and the surface of the test area. The ranging fiber 19 is used to transmit the ranging signal to the control system 7. The sensing unit 20 is used to measure the temperature, humidity, and air pressure near the three-wavelength objective lens 15. A USB cable 21 is used to transmit the sensor measurement information to the control system 7. A high-precision motion stage 22 is used to drive the probe in planar motion to achieve uniform laser-induced breakdown spectrum scanning test. It can also be adjusted along the Z-axis to ensure that the laser is accurately focused on the sample surface. A power and communication cable 23 powers the high-precision motion stage 22, transmits the motion trajectory given by the control system 7, and sends back the current status information. The precision threaded pair 24 is used to adjust the X-axis pitch angle α and Y-axis deflection angle β of the high-precision motion stage 22, thereby adjusting the parallelism between the objective lens plane and the surface to be measured. The base plate 25 connects the high-precision motion stage 22, the precision threaded pair 24, and the suction cup 26. Three sets of ejector pins are designed under the base plate 25 to achieve initial Z-axis positioning of the probe. The suction cup 26 is used to attach the probe to the metal to be measured, enabling the device to measure aluminum alloys at any angle, including horizontal, inclined, and vertical, and also allowing the device to measure the sensitization of aluminum alloys with irregular surface morphology.

[0033] The long-pass dichroic mirror 14 has high transmittance in the wavelength range of 420 nm or higher and high reflectance in the wavelength range of less than 420 nm. The reflectance of the long-pass dichroic mirror 14 in the wavelength range of less than 420 nm is higher than 90%, and the transmittance of the long-pass dichroic mirror 14 in the wavelength range of 420 nm to 1100 nm is higher than 95%. The three-wavelength objective lens 15 has high transmittance in the second harmonic band, the third harmonic band, and the fourth harmonic band of YAG.

[0034] The energy transmission fiber 9, LIBS signal fiber 17, ranging fiber 19, USB cable 21, and power and communication cable 23 are all housed within the corrugated tube 8. The pulse generation module and the sample detection module are connected via the corrugated tube 8. The probe housing 27 is fixed to the side wall of the base plate 25, and the suction cup 26 is fixed along the edge of the base plate 25. The probe housing 27 has a sealed design. When the suction cup 26 is adsorbed onto the sample to be tested, the entire probe portion and the sample form a sealed space, effectively reducing the influence of external air pressure fluctuations on the plasma and improving detection accuracy and spectral signal stability.

[0035] Inside the housing 28, a combination of a nanosecond pulse laser 1, a beam expander group 2, a first fiber collimator 3, and a power transmission fiber 9 transmits nanosecond pulses to the probe. The second fiber collimator 10, a reflector 11, a first lens 12, and a second lens 13 within the probe then collimate and expand the output beam from the power transmission fiber 9. This "dual-end beam expander-collimator" design improves coupling efficiency and alignment tolerance at the input end, reducing the risk of fiber end-face damage, while adjusting the spot size and divergence angle at the output end, significantly improving transmission robustness. When the three-wavelength objective lens 15 and the laser rangefinder 18 are assembled, the horizontal distance between their optical axes is 21 mm. Figure 3 As shown, the sampling area size is set to With a dot spacing of 0.4mm, 26 rows and 51 columns are collected, for a total of 1326 sampling points.

[0036] Please see Figure 4 The horizontal axis represents wavelength (270–410 nm), and the vertical axis represents intensity (au). Figure 4 The mid-baseline is almost zero, indicating minimal background white light interference. A pair of small peaks (MgI element lines) appear in the 279–281 nm range; the highest peak (intensity close to 100 au, possibly characteristic lines of Al or other metal elements) appears at 309–311 nm; the intensity drops to near zero in the 330–370 nm range; and there are two medium-intensity peaks (values ​​between 40–60 au) in the 380–390 nm range, which are also emission lines of common metal elements. This curve reflects the characteristic ultraviolet-visible spectral lines emitted by the atoms / ions of each element during the cooling process in the high-temperature plasma generated by nanosecond laser excitation of the aluminum alloy sample.

[0037] Please see Figure 5 , Figure 5A scatter plot comparing the system-detected values ​​(vertical axis, mg / cm²) and the values ​​detected by the nitric acid mass loss method (horizontal axis, mg / cm²) is shown, overlaid with a linearly fitted line. The horizontal axis ranges from approximately 5 to 35 mg / cm², and the vertical axis ranges from approximately 5 to 34 mg / cm². The black squares on the scatter plot almost entirely lie on a straight line, indicating a high degree of consistency in sensitization measured by the two methods. Only a few points near the fitted line show slight deviations (e.g., at 10–15 mg / cm²), while the remaining points almost perfectly match the line. The R² value of 0.9930, as indicated in the figure, shows that the regression model explains 99.3% of the data variation, demonstrating excellent linear correlation. Overall, the system-detected results show a near 1:1 linear relationship with the traditional nitric acid mass loss method values, validating the accuracy and feasibility of sensitization detection in aluminum alloys.

[0038] Implementation Principle: The nanosecond pulsed laser 1 can be configured with parameters via the integrated processing motherboard 4. The signal delay generator 5 generates a flash signal and a Q-switching signal to trigger the light output control. The laser output from the laser is guided to the probe section through the energy transmission fiber 9, and output as collimated light with a diameter of about 4mm by the second fiber collimator 10. The beam diameter remains approximately constant as it propagates over a certain distance. Then, the beam passes through the reflector 11 and enters the Galilean beam expander group 2 composed of the first lens 12 and the second lens 13. After passing through the beam expander, the beam diameter is about 8mm, which is approximately the entrance pupil diameter of the three-wavelength objective lens 15. After that, the laser passes through a long-pass dichroic mirror 14. This dichroic mirror is used to separate the laser from the laser-induced breakdown spectrum of the 280-400nm wavelength component. The light beams are combined into a coaxial path to separate the signal light from the excitation light, enabling subsequent monitoring of the signal light. Furthermore, after passing through a long-pass dichroic mirror 14, the laser beam is focused onto the sample surface by a three-wavelength objective lens 15. High-energy laser irradiation of the sample surface causes ablation and generates plasma. During plasma cooling, characteristic spectra related to elements are emitted outward. The signal light within the 280-400 nm wavelength range is separated by the long-pass dichroic mirror 14, reflected, and then enters a reflective fiber collimator 16. It is then coupled into the LIBS signal fiber 17 and fed into a miniature fiber optic spectrometer 6 to obtain LIBS spectral data, which is then sent to the integrated processing motherboard 4. Combined with the deployed artificial intelligence neural network processing algorithm, the sensitization of the aluminum alloy is monitored.

[0039] In this embodiment, the high-energy excitation pulse and the LIBS signal optical path are precisely separated by a long-pass dichroic mirror 14, ensuring high transmittance of the excitation light and avoiding interference in the signal path, thus improving the signal-to-noise ratio. The second fiber collimator 10, reflector 11, dual lenses, three-wavelength objective lens 15, and reflective fiber collimator 16 are integrated on an optical path adjustment frame. Combined with a high-precision motion stage 22, the vertical distance between the objective lens plane and the sample plane can be precisely adjusted, ensuring the focusing accuracy of the excitation light and the signal collection efficiency, achieving reproducible optical path alignment. Using a specially designed LIBS signal fiber 17 and a reflective collimator, the device effectively receives the weak spectral signal generated after the alloy under test 30 is excited, and transmits it stably back to the pulse generation module for real-time analysis. Furthermore, the overall optical path and mechanical structure of the device are optimized for the microstructure and sensitization characteristics of aluminum alloys, enabling high-sensitivity detection of trace element precipitation and phase transition states, thus improving the accuracy and reliability of aluminum alloy sensitization assessment. Through the electrical separation of the pulse generation module and the sample detection module, the entire device is small in size and light in weight, making it easy to carry and deploy quickly on site.

[0040] Based on the above system, this application also provides a split-type LIBS aluminum alloy sensitization field detection method, the method including steps S1~S5. S1, configure and preheat the nanosecond pulse laser 1 in the pulse generation module.

[0041] S2, attach the sample detection module to the surface of the metal to be tested. The high-precision motion stage 22 in the sample detection module, together with the laser rangefinder 18, detects the parallelism between the test area of ​​the metal to be tested and the three-wavelength objective lens 15, and adjusts the X-axis and Y-axis pitch of the high-precision motion stage 22 according to the decoupling algorithm.

[0042] In this step, the pitch adjustment mechanism is implemented using three sets of precision threaded pairs 24, which are distributed at three corner points with the center of the objective lens as the center of the hypotenuse of a right triangle. The right-angle point is used as a fixed point, and the other two points are used as adjustment points. They correspond to the pitch angle α and deflection angle β of the two right-angled sides, respectively. By adjusting the height of the two corner points, the pitch angle α and deflection angle β are changed, thereby achieving the parallelism adjustment between the objective lens plane and the surface to be measured.

[0043] S3, the high-precision motion stage 22 is used in conjunction with the laser rangefinder 18 to perform surface shape fitting on the area to be measured. Based on the surface shape fitting result, the high-precision motion stage 22 is adjusted to adjust the Z-axis position of the three-wavelength objective lens 15. When the distance between the three-wavelength objective lens 15 and the metal to be measured is less than or equal to the preset distance, the nanosecond pulse laser 1 is triggered to generate a high-energy excitation pulse, and the LIBS signal, temperature, humidity and air pressure of the metal to be measured after excitation are collected.

[0044] In this step, a rangefinder method is used, with the ranging optical axis parallel to the objective lens optical axis and their positions fixed by mechanical clamps to ensure ranging accuracy. During the detection process, the motion stage drives the rangefinder to scan the area to be measured point by point, acquiring the height data of each detection point in real time. Subsequently, the system performs statistical analysis on all acquired data to calculate the median height. Choosing the median as the benchmark effectively suppresses the impact of outliers on the overall height estimation and minimizes the subsequent Z-axis adjustment range, improving the system's response speed and stability. Based on the difference between the median and the original focal length of the objective lens, the system makes an initial adjustment to the Z-axis to make the median position coincide with the objective lens focal height position, thereby minimizing the focal length deviation of most detection points. Subsequently, in the actual LIBS detection process, whenever the displacement stage moves the objective lens to a new detection point, the system fine-tunes the current point based on the pre-acquired height information, ensuring precise alignment of the objective lens focal point with the point to be measured through real-time Z-axis adjustment, before triggering laser excitation to acquire the spectral signal. This dynamic focusing mechanism can compensate for the unevenness of the sample surface in real time throughout the detection process, ensuring the consistency of laser focusing and the accuracy of LIBS signal acquisition.

[0045] S4, move the high-precision motion stage 22 to the next test area according to the preset path, trigger the nanosecond pulse laser 1 again to generate a high-energy excitation pulse, and collect the LIBS signal of the corresponding area. Repeat the measurement process until the collected LIBS signal meets the spectral quantity threshold.

[0046] S5. Based on the spectral data, temperature, humidity and air pressure in each LIBS signal, construct a quantitative model of aluminum alloy sensitization. Input the real-time LIBS signal into the quantitative model of aluminum alloy sensitization to obtain the alloy sensitization.

[0047] In this step, the analysis of spectral data includes preprocessing algorithms and quantitative analysis algorithms. Preprocessing algorithms include spectral cropping, outlier filtering, and spectral line normalization. The quantitative analysis algorithm preferably uses an artificial neural network model. During the data input process, additional temperature, humidity, and air pressure information are added to the model; that is, data from three additional channels are added to the original spectral data and then input into the model for training.

[0048] When aluminum alloys undergo sensitization, magnesium (Mg) precipitates along grain boundaries, altering the alloy's physicochemical properties. Higher sensitization levels result in greater Mg precipitation, which is reflected in the intensity of the Mg peak in the spectrum. The sensitization level of the alloy can be mapped from the intensity of the Mg peak.

[0049] This method utilizes a deep learning model to extract spectral features and improves detection accuracy by fusing environmental parameters. To optimize the feature extraction and information fusion process, a two-stage modeling strategy is adopted: first, a feature extraction network is trained based on spectral data, and its parameters are frozen; then, environmental parameters are fused with spectral features, and a fully connected layer is used for final prediction.

[0050] In the first stage, spectral data, after preprocessing, is input into a convolutional neural network for feature extraction. Spectral data typically contains multiple channels, each corresponding to light intensity information at different wavelengths. To capture high-dimensional spectral features, particular attention is paid to the intensity information of the Mg peaks (383nm and 280nm). A weighting mechanism is introduced after the input layer in the network structure to highlight the intensity information of the Mg peaks (383nm and 280nm). During feature extraction, multi-layer one-dimensional convolutional operations are used to extract local spectral features. Simultaneously, a Batch Normalization layer is introduced to ensure the stability of features across different training batches, preventing gradient vanishing or exploding problems. Finally, a fully connected layer performs a nonlinear mapping of the spectral features to form a high-dimensional feature vector, which is then trained using a mean squared error loss function and the Adam optimizer. After model training is complete, the parameters of this part are frozen, serving as a stable pre-trained model for the subsequent feature fusion stage.

[0051] Weighting mechanism: , For spectral data, For the weighted spectral data, To initialize the weight matrix, high values ​​are assigned to the wavelength positions corresponding to the Mg peak, and low values ​​are assigned to the other positions.

[0052] Multi-layer one-dimensional convolution: , The features output by the k-th convolutional kernel For activation function, For convolution kernel weights, For bias.

[0053] Batch Normalization layer: , This is the output feature map of the convolutional layer. This is the average value of the current batch. This represents the variance of the current batch. To prevent small constants from being divided by zero, (scaling factor) and The offset is used to preserve the network's ability to recover the original feature distribution.

[0054] Mean squared error loss function: , Let i be the true value of the i-th sample. Let be the predicted value for the i-th sample.

[0055] In the second stage, environmental parameters (temperature, humidity, and air pressure) are input into the fully connected layer for feature encoding. Since environmental factors affect the LIBS plasma state and spectral signals, especially the intensity of the Mg peak which may change under different air pressures, this invention introduces an independent feature transformation layer during environmental parameter modeling. This layer maps the environmental parameters to a high-dimensional space identical to the spectral features, ensuring they have the same feature dimension during fusion. To achieve efficient fusion of spectral data and environmental parameters, the `torch.cat()` function is used to concatenate along the feature dimension. The fused high-dimensional feature vector is then input into the fully connected layer for sensitization prediction, thereby constructing a complete sensitization detection model.

[0056] During training and optimization, a learning rate decay strategy was adopted, reducing the learning rate by a factor of 0.92 after every 10 training epochs to improve the model's convergence performance and prevent overfitting. Furthermore, cross-validation was used to evaluate the model's generalization ability, and TensorBoard was used to visualize the training process to optimize hyperparameter tuning. In the testing phase, the mean squared error (MSE) and coefficient of determination (R²) were calculated using an independent test set to evaluate model performance and optimize the network structure. Simultaneously, the variation trend of Mg peak intensity under different environmental conditions was further analyzed to verify the model's stability and adaptability under various operating conditions.

[0057] A single spectral data point acquired by the spectrometer is a one-dimensional data point with a length of 2100. However, the spectral amplitude in the 0-500 range is almost zero, increasing redundant information in the algorithm's learning process. To reduce interference from irrelevant information, only data points from 501 to 2100 are retained. Due to factors such as the spectrometer's acquisition environment, human error, and differences in metal surfaces, some waveform data may exhibit anomalies within the same time period. To reduce the impact of abnormal spectral data on training accuracy, all acquired spectral data is filtered, removing abnormal spectral data that are 130% above the mean and 60% below the mean, thus enhancing the model's effectiveness. To eliminate differences in experimental conditions and signal intensity, accelerate model convergence, and improve the comparability of spectral data and model stability, maximum value normalization is employed, mapping the spectral intensity to the range [0,1].

[0058] By combining a laser rangefinder 18, a high-precision motion stage 22, and three sets of precision threaded pairs 24, automatic adjustment of the X / Y pitch and Z axis is achieved, ensuring that the three-wavelength objective lens 15 is parallel to the sample surface throughout the entire test area and is always at the optimal focal length. Surface shape fitting further compensates for the slight curvature or warping of the sample, reduces focusing errors, improves spot consistency, stabilizes signal intensity, and presets path movement and triggering logic, which can automatically cycle and collect LIBS signals in multiple areas, avoiding manual handling and repeated focusing, significantly improving detection throughput and consistency. Simultaneously, environmental information such as temperature, humidity, and air pressure is collected and used as input for subsequent quantitative model calculations, effectively eliminating the influence of external condition fluctuations on spectral signals and enhancing measurement accuracy. The split modular design combined with the automated measurement process makes deployment rapid and operation simple, greatly shortening the detection cycle, and is suitable for the inspection of aluminum alloy components with large-area structures or multi-point layouts.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A split type LIBS aluminum alloy sensitization degree on-site detection device, characterized in that, The sample detection module comprises a transmission optical fiber (9), a second optical fiber collimator (10), a reflector (11), a first lens (12), a second lens (13), a long-wave-pass dichroic mirror (14), a three-wavelength objective lens (15), a reflective optical fiber collimator (16), a LIBS signal optical fiber (17), a high-precision motion stage (22), a power supply and communication line (23), a precision threaded pair (24), and a bottom plate (25). The transmission optical fiber (9), the LIBS signal optical fiber (17), and the power supply and communication line (23) are all connected with the pulse generation module, the high-energy excitation pulse is transmitted by the transmission optical fiber (9) through the second optical fiber collimator (10), the reflector (11), the first lens (12), and the second lens (13) to the long-wave-pass dichroic mirror (14) in sequence, the high-energy excitation pulse is focused to the alloy to be measured (30) through the long-wave-pass dichroic mirror (14) and the three-wavelength objective lens (15) in sequence, the LIBS signal generated by the alloy to be measured (30) excited by the high-energy excitation pulse is reflected to the reflective optical fiber collimator (16) through the long-wave-pass dichroic mirror (14), and is transmitted to the pulse generation module through the LIBS signal optical fiber (17). The second optical fiber collimator (10), the reflector (11), the first lens (12), the second lens (13), the long-wave-pass dichroic mirror (14), the three-wavelength objective lens (15), and the reflective optical fiber collimator (16) are all arranged on an optical path debugging rack, the optical path debugging rack and the high-precision motion stage (22) are both mounted on the bottom plate (25), the high-precision motion stage (22) transmits information with the pulse generation module through the power supply and communication line (23), and the high-precision motion stage (22) is used for adjusting the vertical distance between the objective lens plane and the alloy surface to be measured. The sample detection module further comprises a laser range finder (18), a ranging optical fiber (19), a sensing unit (20), and a USB line (21), the laser range finder (18) and the sensing unit (20) are both arranged on the optical path debugging rack, the laser range finder (18) is connected with the pulse generation module through the ranging optical fiber (19), the laser range finder (18) is used for measuring the distance between the three-wavelength objective lens (15) and the surface of the alloy to be measured (30), the sensing unit (20) is connected with the pulse generation module through the USB line (21), and the sensing unit (20) is used for measuring the temperature, humidity, and air pressure around the three-wavelength objective lens (15).

2. The split LIBS aluminum alloy sensitivity on-site detection device according to claim 1, wherein, ​ 3. The split LIBS aluminum alloy sensitivity on-site detection device according to claim 2, wherein, The pulse generation module comprises a nanosecond pulse laser (1), an expander lens group (2) and a first fiber collimator (3) arranged on the light path of the nanosecond pulse laser (1), a comprehensive processing mainboard (4), a signal delay generator (5), a miniature fiber spectrometer (6) and a control system (7), wherein, The first fiber collimator (3) is connected with the sample detection module through the energy transmission fiber (9), the comprehensive processing mainboard (4) is connected with the nanosecond pulse laser (1), the signal delay generator (5), the miniature fiber spectrometer (6) and the control system (7) respectively, the signal delay generator (5) is connected with the nanosecond pulse laser (1) and the miniature fiber spectrometer (6) respectively, the miniature fiber spectrometer (6) is connected with the sample detection module through the LIBS signal fiber (17) electrically, the control system (7) is connected with the signal delay generator (5), and the control system (7) is connected with the sample detection module through the distance measuring fiber (19), the USB line (21) and the power supply and communication line (23) respectively.

4. The split LIBS aluminum alloy sensitivity on-site detection device of claim 2, wherein, The sample detection module further comprises three sets of precision threaded pairs (24), the high-precision motion table (22) is fixed on the bottom plate (25) by the three sets of precision threaded pairs (24), the three sets of precision threaded pairs (24) are distributed at the three top corners of the high-precision motion table (22), the three sets of precision threaded pairs (24) connected form a right triangle, the precision threaded pair (24) at the right angle point is used as a fixed point, and the remaining precision threaded pairs (24) are used as adjustment points, the pitch angle and the deflection angle of the high-precision motion table (22) are adjusted, the parallelism between the three-wavelength objective lens (15) and the surface of the alloy to be measured (30) is adjusted, and the Z-axis position of the three-wavelength objective lens (15) is adjusted by the high-precision motion table (22), so that the distance between the surface of the alloy to be measured (30) and the three-wavelength objective lens (15) is constant.

5. The split LIBS aluminum alloy sensitization degree on-site detection device according to claim 2, wherein, The sample detection module further comprises a plurality of suction cups (26), and the suction cups (26) are arranged on the side of the bottom plate (25) away from the high-precision motion table (22).

6. The split LIBS aluminum alloy sensitization degree on-site detection device according to claim 1, wherein, The long-wave pass dichroic mirror (14) has high transmittance in a wavelength band greater than or equal to 420 nm and high reflectivity in a wavelength band less than 420 nm, the reflectivity of the long-wave pass dichroic mirror (14) in the wavelength band less than 420 nm is higher than 90%, and the transmittance of the long-wave pass dichroic mirror (14) in the wavelength band of 420 nm to 1100 nm is higher than 95%.

7. The split LIBS aluminum alloy sensitization degree on-site detection device according to claim 1, wherein, The three-wavelength objective lens (15) has high transmittance in the 2nd harmonic wave band of YAG, the 3rd harmonic wave band of YAG and the 4th harmonic wave band.

8. The split LIBS aluminum alloy sensitivity on-site detection device of claim 3, wherein, The nanosecond pulse laser (1) has an output wavelength of 532 nm, a pulse width of less than 10 ns, and a repetition frequency of 1-100 Hz; the micro fiber spectrometer (6) has a wavelength range of 270 nm-410 nm and a spectral resolution of higher than 0.1 nm.

9. The split LIBS aluminum alloy sensitivity on-site detection device of claim 2, wherein, The energy transmission fiber (9), the LIBS signal fiber (17), the distance measuring fiber (19), the USB line (21), and the power supply and communication line (23) are arranged in the bellows (8), and the pulse generation module and the sample detection module are connected through the bellows (8).

10. A split-body LIBS aluminum alloy sensitization degree on-site detection method, characterized in that, The method comprises: The nanosecond pulse laser (1) in the pulse generation module is configured and preheated; The sample detection module is attached to the surface of the metal to be measured, the high-precision motion stage (22) in the sample detection module cooperates with the laser distance meter (18) to detect the parallelism between the to-be-measured region of the metal to be measured and the three-wavelength objective lens (15), and adjusts the X-axis and Y-axis tilting of the high-precision motion stage (22) according to the decoupling algorithm; The high-precision motion stage (22) cooperates with the laser distance meter (18) to perform surface fitting on the to-be-measured region, and adjusts the Z-axis position of the three-wavelength objective lens (15) according to the surface fitting result, so that when the distance between the three-wavelength objective lens (15) and the metal to be measured is less than or equal to a preset distance, the nanosecond pulse laser (1) is triggered to generate a high-energy excitation pulse, and the LIBS signal, temperature, humidity, and air pressure of the metal to be measured after excitation are collected; The high-precision motion stage (22) moves to the next to-be-measured region according to a preset path, the nanosecond pulse laser (1) is triggered again to generate a high-energy excitation pulse, and the LIBS signal of the corresponding region is collected, and the measurement process is repeated until the number of collected LIBS signals meets a spectral quantity threshold; According to the spectral data, temperature, humidity, and air pressure in each LIBS signal, an aluminum alloy sensitization degree quantitative model is constructed, and a real-time LIBS signal is input into the aluminum alloy sensitization degree quantitative model to obtain the alloy sensitization degree.

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