A multi-sound-field-based stress regulation method for a laser cladding layer

Abstract

The application discloses a laser cladding layer stress regulation method based on multiple sound fields, establishes an ultrasonic signal amplitude and ultrasonic amplitude quantitative relationship formula, gradually loads multiple laser layer static load tensile samples under multiple different ultrasonic amplitudes, establishes a propagation time difference and loading load corresponding relationship formula and multiple calibrated ultrasonic wave acoustic elastic coefficients and multiple different ultrasonic amplitude quantitative expressions; the ultrasonic wave signal amplitude of the laser cladding layer to be regulated is collected, the ultrasonic amplitude and the ultrasonic wave acoustic elastic coefficient are obtained, the multiple calibrated ultrasonic wave acoustic elastic coefficients are compared, the optimal ultrasonic amplitude corresponding to the ultrasonic wave acoustic elastic coefficient with the minimum error absolute value is obtained, the critical refracted longitudinal wave signal of the optimal ultrasonic amplitude and when not loaded is taken as a reference signal, the time difference between the ultrasonic wave signal and the reference signal is calculated, and a stress value is obtained; the application realizes the mapping correlation among the ultrasonic amplitude, the ultrasonic wave acoustic elastic coefficient and the stress, and realizes the elimination of the laser cladding layer stress by controlling the ultrasonic vibration energy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ultrasonic application, and particularly relates to an ultrasonic technology capable of quickly and non-destructively realizing coating stress regulation. BACKGROUND

[0002] Laser cladding technology has attracted wide attention in the field of mechanical equipment remanufacturing. Relevant research shows that stress is one of the key factors affecting the quality of remanufactured laser cladding layer and even laser cladding remanufactured products. Therefore, it is extremely important to explore and develop a technical method capable of realizing stress regulation of the laser cladding layer. At present, the technical methods for regulating the stress of the laser cladding layer mainly focus on the following three aspects: ① optimization of the laser cladding process; ② research and development of new laser cladding equipment and methods; and ③ research and development of new laser cladding materials. Although the above methods have achieved a certain degree of control of the stress of the laser cladding layer, there are still obvious problems: one of the characteristics of laser cladding is fast cooling speed, which causes directional solidification of the structure and stress induced thereby, and the above regulation methods not only need to repeat a large number of experiments, but also are affected by random factors in the laser cladding process, so it is difficult to achieve the expected control of the stress of the laser cladding layer.

[0003] Ultrasonic vibration is a kind of power ultrasound, which is a technical method for changing the state of some properties through ultrasonic energy. It has the advantages of convenience, controllability and easy application. Ultrasonic stress evaluation technology is a stress evaluation technology based on the ultrasonic acoustic elasticity effect in solid medium, which has the advantages of non-destructive, fast, convenient and harmless, and is applied in the field of stress evaluation. For example, the method disclosed in the document with the Chinese patent application publication number CN111504530A and the name of "a method for quickly and non-destructively regulating the stress of a cladding layer based on ultrasonic technology" is based on the ultrasonic acoustic elasticity theory, combines with the static load tensile calibration method, establishes the ultrasonic acoustic elasticity formula of the cladding layer in the tensile and compression states, and prepares cladding layer samples in different compression stress states through ultrasonic impact technology. The method takes the ultrasonic time delay caused by stress as an "intermediate variable", establishes the corresponding correlation between the stress and the ultrasonic impact coverage, and then realizes the non-destructive and rapid regulation of the stress of the cladding layer. However, the method has the following defects: it is based on sampling under a single ultrasonic amplitude, and the ultrasonic signals of the cladding layer before / after impact are collected, and the variables in the cladding process are not detected. In the cladding process, the cooling speed is fast, the directional solidification of the structure causes large stress changes, and there are random factors. Therefore, the accuracy of the stress control of the cladding layer in the cladding process is not high. SUMMARY

[0004] In view of the problem of low accuracy in the current stress control of the laser cladding layer, the application provides a laser cladding layer stress control method based on multiple sound fields, which can accurately, quickly and non-destructively control the stress of the laser cladding layer.

[0005] To achieve the above object, the technical scheme of the stress control method for laser cladding layer based on multiple sound fields is as follows:

[0006] Step 1): multiple ultrasonic vibrators are used to apply multiple different ultrasonic amplitudes during the preparation of laser cladding layers Multiple laser cladding layer samples are prepared, and the ultrasonic signal amplitudes of the multiple laser cladding layer samples are extracted The quantitative relationship between the ultrasonic signal amplitude and the ultrasonic amplitude is established The quantitative expression of the multiple calibrated ultrasonic acoustic elastic coefficients k and the multiple different ultrasonic amplitudes is established

[0007] Step 2): multiple laser layer static load tensile samples under the multiple different ultrasonic amplitudes are processed, the multiple laser layer static load tensile samples are respectively loaded step by step, the propagation time difference Δt of the ultrasonic wave signal is collected in sequence, the corresponding relationship between the propagation time difference Δt and the loading load σ is established, the multiple calibrated ultrasonic acoustic elastic coefficients k in the corresponding relationship are extracted, and the quantitative expression of the multiple calibrated ultrasonic acoustic elastic coefficients k and the multiple different ultrasonic amplitudes is established

[0008] Step 3): the ultrasonic signal amplitude A' of the laser cladding layer to be controlled is collected, the ultrasonic amplitude z' is obtained by using the quantitative relationship between the ultrasonic signal amplitude and the ultrasonic amplitude in step 1), and the ultrasonic acoustic elastic coefficient k' of the laser cladding layer to be controlled is obtained by using the quantitative expression of the multiple calibrated ultrasonic acoustic elastic coefficients k and the multiple different ultrasonic amplitudes in step 2) based on the ultrasonic amplitude z';

[0009] Step 4): the ultrasonic acoustic elastic coefficient k' is compared with the multiple calibrated ultrasonic acoustic elastic coefficients k, the optimal ultrasonic amplitude corresponding to the ultrasonic acoustic elastic coefficient k with the minimum error absolute value is obtained, and the critical refracted longitudinal wave signal of the laser cladding layer to be controlled under the optimal ultrasonic amplitude and without loading is used as a reference signal

[0010] Step 5): the time difference between the ultrasonic signal applied on the laser cladding layer to be controlled and the reference signal is calculated, and the stress value on the laser cladding layer to be controlled is obtained according to the corresponding relationship between the propagation time difference Δt and the loading load σ in step 2).

[0011] The above technical scheme has the following advantages:

[0012] ​​​​​​1. The application prepares a plurality of coating samples with different ultrasonic amplitudes, first, the ultrasonic vibration amplitude (energy) is controlled to change the coating organization and stress state, and the ultrasonic acoustic elasticity coefficient calibration experiment is used, based on the ultrasonic acoustic elasticity theory, combined with the static load tensile calibration method, and then the corresponding correlation between the ultrasonic acoustic elasticity coefficient and the ultrasonic amplitude is obtained, and finally the ultrasonic regulation and control of the coating stress are realized, which not only provides a non-destructive method for the evaluation of the coating stress, but also provides a convenient and effective method for the control of the coating stress, with the advantages of rapidity, convenience, safety and online.

[0013] 2. Compared with the method disclosed in the document with the patent publication number CN111504530A, the main innovation of the application is:

[0014] (1) The method disclosed in the document with the patent publication number CN111504530A is based on sampling under a single ultrasonic amplitude. The application is based on sampling under multiple different ultrasonic amplitudes during the cladding process stage.

[0015] (2) The method disclosed in the document with the patent publication number CN111504530A collects ultrasonic signals of the cladding layer under different stresses in the elastic deformation range, calculates the time delay between the ultrasonic signals, fits the time delay and the stress, and obtains the ultrasonic acoustic elasticity formula of the cladding layer sample under tensile / compressive stress state. The application establishes the corresponding relationship formula of the propagation time difference and the loading load, extracts multiple calibrated ultrasonic acoustic elasticity coefficients in the corresponding relationship formula, and establishes a quantitative expression of multiple calibrated ultrasonic acoustic elasticity coefficients and multiple different ultrasonic amplitudes.

[0016] (3) The method disclosed in the document with the patent publication number CN111504530A sequentially collects ultrasonic signals of the cladding layer before and after impact and under different coverages, compares the ultrasonic signals of the cladding layer after impact with the ultrasonic signals of the cladding layer before impact to obtain the time delay. The application sequentially collects ultrasonic signals during the ultrasonic process to obtain the propagation time difference.

[0017] (4) The method disclosed in the document with the patent publication number CN111504530A fits the coverage and the time delay of the cladding layer before and after impact to establish the relationship between the ultrasonic impact coverage and the stress. The application obtains the stress value according to the corresponding relationship formula of the propagation time difference and the loading load.

[0018] Therefore, the application realizes the mapping correlation between the ultrasonic amplitude, the ultrasonic acoustic-elastic coefficient and the stress by correlating the energy attenuation of the ultrasonic signal induced by the laser cladding layer structure and the ultrasonic wave propagation speed induced by the stress of the laser cladding layer, establishes the corresponding relationship between the ultrasonic wave evaluation laser cladding layer stress and the characteristic parameters of the laser cladding layer stress changed by the ultrasonic vibration, realizes the elimination of the laser cladding layer stress by controlling the ultrasonic vibration energy, and is integrated with the ultrasonic wave evaluation laser cladding layer stress evaluation technology, thereby forming a stress closed-loop control, which is different from the open-loop control method disclosed in the document with the patent publication number CN111504530A, so that the control of the structure in the laser cladding process is realized, and the nondestructive evaluation of the laser cladding layer stress is realized.

[0019] 3、The application combines the ultrasonic vibration and the ultrasonic wave evaluation stress technology, that is, firstly, the stress state in the laser cladding process is changed by controlling the ultrasonic vibration energy, secondly, the actual stress is evaluated by the ultrasonic wave, and finally, the actual stress of the laser cladding layer subjected to the ultrasonic vibration provides the basis and foundation for the later stress regulation, provides the technical support and theoretical basis for realizing the control of the laser cladding layer stress, provides the technical support for the quality and reliability evaluation of the laser cladding layer, reduces or even avoids the service safety hidden danger of the remanufactured product. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the relationship curve diagram between the ultrasonic wave amplitude and the critical refraction longitudinal wave receiving signal amplitude in the embodiment of the application.

[0021] Figure 2 It is the relationship curve diagram between the ultrasonic wave signal acoustic-elastic coefficient and the ultrasonic amplitude in the embodiment of the application. DETAILED DESCRIPTION

[0022] This invention discloses a multi-field laser cladding layer stress control method. A coating of a certain thickness is prepared on the surface of a test substrate using laser cladding. The coating is a metallic coating, including metallurgically bonded and non-metallurgically bonded coatings. The coating thickness is between 0.5 and 6 mm, with the coating thickness error of the test substrate not exceeding ±5%, and the error with the ultrasonic detection depth not exceeding ±5%. The coating roughness is not greater than Ra1.6. At least three sets of ultrasonic vibrators are used. Based on the thickness of the substrate, the auxiliary devices of the multiple sets of ultrasonic vibrators are adjusted to ensure good contact between all ultrasonic vibrators and the substrate, ensuring the effectiveness of ultrasonic vibration and ensuring that the propagation of ultrasonic waves in the coating is not less than its near-field. The amplitude range is optimized by adjusting the ultrasonic signal excitation parameter M based on the maximum and minimum attenuation values ​​of the ultrasonic energy signal (i.e., the amplitude of the received ultrasonic signal), ensuring that the minimum ultrasonic signal amplitude is not less than 20% of the maximum amplitude. Then, the ultrasonic signal excitation parameter M is kept constant to ensure good and stable coupling between the ultrasonic probe and the coating surface.

[0023] During the laser cladding process, multiple different ultrasonic amplitudes were applied to the test base plate. Change the ultrasonic amplitude sequentially Different ultrasonic amplitudes were prepared Multiple laser cladding layer samples were tested under different ultrasonic amplitudes. Simultaneously, the ultrasonic mode used for detection was selected as critical refraction longitudinal wave, the ultrasonic excitation energy parameters and propagation distance were kept constant, and ultrasonic amplitudes of different applications were collected and extracted. Multiple ultrasonic signal amplitudes corresponding to multiple laser cladding layer samples For multiple ultrasonic amplitudes and multiple ultrasonic signal amplitudes Fitting is performed to establish the amplitude of the ultrasonic signal. With ultrasonic amplitude The corresponding fitting relationship is obtained as follows: (1) Ultrasonic signal amplitude With ultrasonic amplitude Quantitative relationship:

[0024]

[0025] In the formula: represents the fitting coefficient.

[0026] Based on the static tensile test standard for metallic materials at room temperature, materials were processed under different ultrasonic amplitudes. Multiple laser-layer static tensile specimens were subjected to stress relief treatment using heat treatment. The stress was then measured at different ultrasonic amplitudes. the yield strength of the laser layer static load tensile sample. The maximum load is set as the yield strength of the laser layer static load tensile sample, the ultrasonic signal of the laser layer static load tensile sample when no load is defined as the reference signal, the number of loads is ensured to be not less than 5 groups, and based on this, the multiple laser layer static load tensile samples are loaded step by step. After the load is stable, the propagation time difference Δt of the ultrasonic signal of the multiple laser layer static load tensile samples under the load is collected in turn, and the corresponding relationship between the propagation time difference Δt and the load σ is established by using the following formula (2). The corresponding relationship formula has a calibrated ultrasonic acoustic elastic coefficient k:

[0027] Δt = kσ + c (2)

[0028] σ is the load (MPa), c is the fitting coefficient, and k is the calibrated ultrasonic acoustic elastic coefficient. One calibrated ultrasonic acoustic elastic coefficient k corresponds to one laser layer static load tensile sample, so multiple calibrated ultrasonic acoustic elastic coefficients k are obtained.

[0029] Based on the corresponding relationship between the propagation time difference Δt and the load σ in formula (2), the calibrated ultrasonic acoustic elastic coefficient k is extracted, the corresponding relationship between the calibrated ultrasonic acoustic elastic coefficient k and different ultrasonic amplitudes is established, and the numerical values conforming to the monotonic change rule are fitted by using the following formula (3) polynomial to obtain a quantitative expression.

[0030]

[0031] In the formula, d, e, and f are fitting coefficients, is the ultrasonic amplitude.

[0032] For the laser cladding layer to be controlled, the same ultrasonic signal excitation parameter M is applied, the ultrasonic signal of the laser cladding layer to be controlled is collected, the ultrasonic signal amplitude A' of the laser cladding layer to be controlled is proposed, and the ultrasonic signal amplitude A' is substituted into formula (1) to replace to obtain the ultrasonic amplitude z' corresponding to the ultrasonic signal amplitude A'.

[0033] The ultrasonic amplitude z' is substituted into the corresponding relationship formula (3) between the calibrated ultrasonic acoustic elastic coefficient k and different ultrasonic amplitudes , and different ultrasonic amplitudes z' are substituted into formula (3) to obtain the corresponding ultrasonic acoustic elastic coefficient k' of the laser cladding layer to be controlled.

[0034] The ultrasonic acoustic elastic coefficient k' of the laser cladding layer to be regulated is compared with a plurality of calibrated ultrasonic acoustic elastic coefficients k, and the ultrasonic acoustic elastic coefficient k with the minimum absolute error of the two is selected as the optimal ultrasonic acoustic elastic coefficient, the optimal ultrasonic amplitude corresponding to the optimal ultrasonic acoustic elastic coefficient is obtained, the optimal ultrasonic amplitude corresponding to the optimal ultrasonic acoustic elastic coefficient is used as the ultrasonic amplitude applied to the laser cladding layer to be regulated, and the critical refracted longitudinal wave signal of the optimal ultrasonic amplitude corresponding to the optimal ultrasonic acoustic elastic coefficient and not loaded is used as the reference signal A0.

[0035] The time difference At' of the ultrasonic signal with the amplitude A' applied to the laser cladding layer to be regulated and the reference signal A0 is calculated, the time difference At' is substituted into the formula At=kσ+c, At' replaces At therein, the stress value σ' on the laser cladding layer to be regulated is obtained according to the corresponding relationship between the propagation time difference and the loaded load, and thus the regulation of the stress of the laser cladding layer is realized.

[0036] An embodiment of the present application is provided below:

[0037] Embodiment

[0038] Q235 steel is selected as the base material of the test bottom plate, a laser cladding method is a coating preparation technology, and the present application is described by taking the preparation of a laser cladding layer on the surface of the Q235 steel as an example, and the specific process is as follows:

[0039] In step one, Q235 steel with a thickness of 20 mm is selected as the base material of the test bottom plate, a laser cladding method is a coating preparation technology, a cladding powder is Fe314 alloy powder, and the main process parameters for preparing the laser cladding layer are as follows: a laser power is 1.7 kW, a laser cladding rate is 3 mm / s, a protective gas is argon, and powder is fed laterally.

[0040] An ultrasonic vibration mode in the form of a longitudinal wave is selected, an ultrasonic vibrator is placed horizontally and in close contact with the side (thickness direction) of the Q235 steel plate. Ultrasonic amplitudes of 0% (not applied), 10%, 50%, and 90% of the maximum amplitude ratio are used Four Fe314 alloy laser cladding layer samples with a thickness of (1.2±0.15) mm are prepared by applying different ultrasonic amplitudes of 0%, 10%, 50%, and 90% of the maximum amplitude ratio respectively during the preparation of the laser cladding layer

[0041] Step two: Select the critical refraction longitudinal wave ultrasonic mode for detection, with a center frequency of 2.5MHz for the ultrasonic probe, and adopt a one-transmitter-one-receiver mode. The ultrasonic propagation distance between the two ultrasonic probes is 30mm (greater than their near-field distance). Fix the ultrasonic signal excitation parameters and coupling state, and sequentially collect four sets of data with different ultrasonic amplitudes. The critical refractive longitudinal wave signals of the laser cladding layer were received, with amplitudes of 32%, 51%, 73%, and 76% of the full screen, respectively.

[0042] Step 3: Extract 4 groups of ultrasound waves with different amplitudes. The critical refractive longitudinal wave received signal amplitude of the laser cladding layer The values ​​were 32mV, 51mV, 73mV, and 76mV, respectively, and their correlation with ultrasonic amplitude was established. The correspondence between them can be found in Figure 1 The critical refracted longitudinal wave signal amplitude is obtained by fitting it with equation (1). With ultrasonic amplitude The quantitative relationship (4):

[0043]

[0044] Step four: According to the standard GB / T2002-228 Metallic Materials - Tensile Testing at Room Temperature, prepare materials subjected to four different ultrasonic amplitudes. Four laser-clad layer static tensile specimens with an overall thickness (laser cladding layer + Q235 steel) of 3.0 mm were subjected to stress-relief annealing using a vacuum stress-relief annealing method. Based on this, the yield strengths of the four laser-clad layer static tensile specimens were measured to be 608 MPa, 652 MPa, 686 MPa, and 635 MPa, respectively, and these were defined as the maximum loading stress.

[0045] Four laser-coated static tensile specimens were subjected to progressively increasing stresses of 0 MPa, 100 MPa, 200 MPa, 300 MPa, 400 MPa, 500 MPa, 600 MPa, and the maximum stress, with the initial stress not exceeding 5% of the yield strength. The critical refractive longitudinal wave signals of the laser cladding layer were collected for each of the four laser-coated static tensile specimens during progressive loading. The time difference between the received signals was taken as the propagation time difference Δt, and a relationship between the propagation time difference Δt and the loading load σ (i.e., stress) was established, as shown in equation (5):

[0046]

[0047] In the formula, Δt is the time difference between ultrasonic signals (ns), and σ is the stress (MPa). Thus, four different calibrated ultrasonic acoustic elastic k formulas are obtained. From equation (5), the four different calibrated ultrasonic acoustic elastic k values ​​are 0.108, 0.163, 0.196, and 0.203, all in ns / MPa.

[0048] Step 5: Extract the equation (5) by applying different ultrasonic amplitudes. The calibrated ultrasonic acoustoelastic coefficient k of the laser cladding layer is established, and its relationship with the ultrasonic amplitude is determined. The correspondence is shown in the following figure. Figure 2 The ultrasonic acoustic elastic coefficient and ultrasonic amplitude used for fitting need to satisfy a monotonic change. Equation (3) is used to fit the values ​​that conform to the monotonic change law, and then its quantitative expression is obtained, as shown in Equation (6):

[0049]

[0050] d, e, and f are the fitting coefficients.

[0051] Step 6: Apply the same ultrasonic parameters as in step (2) to the laser cladding layer to be controlled, collect the critical refractive longitudinal wave signal of the laser cladding layer to be controlled, and extract its ultrasonic signal amplitude A′ as 75.2mV. Substitute 75.2mV into equation (4): Right now The corresponding ultrasonic amplitude z′ was calculated, and the ultrasonic amplitude z′ is approximately 71% of the maximum amplitude. Then, the ultrasonic amplitude z′ is substituted into equation (6) to replace... That is, equation (6) becomes: k′=de·f z′ Thus, the ultrasonic acoustic elastic coefficient k′=0.201 of the corresponding laser cladding layer to be controlled can be calculated. Therefore, for the laser cladding layer to be controlled, equation (2) is as follows:

[0052] △t=0.201·σ (7)

[0053] Step 7: Compare the ultrasonic acoustic elastic coefficient k′=0.201 of the laser cladding layer to be controlled with the four different calibrated ultrasonic acoustic elastic coefficients k=0.108, 0.163, 0.196, and 0.203 obtained from the calibration test in equation (5). Calculate the absolute value of the difference between the two. The smallest absolute value of the difference is 0.002=0.203-0.201. Select the ultrasonic acoustic elastic coefficient k with the smallest absolute value of the error as the optimal ultrasonic acoustic elastic coefficient k=0.203. As can be seen from steps 1 and 4, this optimal ultrasonic acoustic elastic coefficient k=0.203 corresponds to the ultrasonic amplitude of 90% of the maximum amplitude in step 1. That is, with ultrasonic amplitude The ultrasonic acoustic-elasticity coefficient of the laser cladding layer sample at 90% of the maximum amplitude is equal to or closest to the ultrasonic acoustic-elasticity coefficient of the laser cladding layer sample at 90% of the maximum amplitude and no load, and then the laser cladding layer sample at 90% of the maximum amplitude is selected as the reference signal A0. The critical refraction longitudinal wave signal of the laser cladding layer sample at 90% of the maximum amplitude and no load is the reference signal A0.

[0054] In step eight, the time difference Δt' between the critical refraction longitudinal wave signal (amplitude A' is 75.2 mv) of the laser cladding layer to be regulated in step six and the reference signal A0 of the laser cladding layer to be regulated selected in step seven is calculated, which is about 66 ns. Substituted into formula (7), Δt=0.201·σ, the stress value σ' of the laser cladding layer to be regulated is calculated to be about 326 Mpa, and the regulation of the stress of the laser cladding layer is realized.

Claims

1. A multi-acoustic field based laser cladding layer stress regulation method, characterized by the following steps: Step 1) : applying multiple different ultrasonic amplitudes using multiple ultrasonic transducers during the laser cladding layer preparation process corresponding multiple laser cladding layer samples are prepared, and the ultrasonic signal amplitudes of the multiple laser cladding layer samples are extracted a quantitative relationship between the ultrasonic signal amplitude and the ultrasonic amplitude is established; Step 2): processing the plurality of laser layer static tensile specimens under different ultrasonic amplitudes respectively, sequentially collecting the propagation time difference Δt of the ultrasonic wave signals, and establishing a corresponding relationship between the propagation time difference Δt and the loading load σ; extracting a plurality of calibrated ultrasonic acoustic elastic coefficients k in the corresponding relationship, and establishing a quantitative expression of the plurality of calibrated ultrasonic acoustic elastic coefficients k and the plurality of different ultrasonic amplitudes ​ Step 3): Collecting the amplitude A' of the ultrasonic signal of the laser cladding layer to be controlled, obtaining the ultrasonic amplitude z' by using the quantitative relationship between the amplitude A' of the ultrasonic signal and the ultrasonic amplitude z' described in step 1); and obtaining the ultrasonic acoustic-elastic coefficient k' of the laser cladding layer to be controlled by using the quantitative expression of the plurality of calibrated ultrasonic acoustic-elastic coefficients k and the plurality of different ultrasonic amplitudes z' described in step 2) based on the ultrasonic amplitude z'. and the quantitative relationship between the amplitude A' of the ultrasonic signal and the ultrasonic amplitude z' ; and obtaining the ultrasonic acoustic-elastic coefficient k' of the laser cladding layer to be controlled by using the quantitative expression of the plurality of calibrated ultrasonic acoustic-elastic coefficients k and the plurality of different ultrasonic amplitudes z' described in step 2) based on the ultrasonic amplitude z'. ​ Step 4): Comparing the ultrasonic acoustic coefficient k' with the plurality of calibrated ultrasonic acoustic coefficients k, obtaining the optimal ultrasonic amplitude corresponding to the ultrasonic acoustic coefficient k with the minimum absolute error value, and taking the critical refracted longitudinal wave signal of the laser cladding layer to be regulated without loading as the reference signal; Step 5): Calculating the time difference between the ultrasonic signal applied to the laser cladding layer to be regulated and the reference signal, and obtaining the stress value on the laser cladding layer to be regulated according to the corresponding relationship between the propagation time difference Δt and the loading load σ in step 2).

2. The multi-acoustic field based laser cladding layer stress regulation method according to claim 1, characterized in that: In step 1), the ultrasonic signal amplitude with the ultrasonic amplitude The quantitative relationship is: is a fitting coefficient.

3. The multi-acoustic field based laser cladding layer stress regulation method according to claim 1, characterized in that: In step 2), the corresponding relationship between the propagation time difference Δt and the loading load σ is: Δt=kσ+c, c is the fitting coefficient.

4. The multi-acoustic-field based laser cladding layer stress regulation method according to claim 3, characterized in that: In step 2), the calibrated ultrasonic acoustic-elasticity coefficient k is correlated with different ultrasonic amplitudes The quantitative expression is: d, e, f are fitting coefficients.

5. The multi-acoustic-field based stress regulation method for laser cladding layers according to any one of claims 1-4, characterized in that: Applying multiple different ultrasound amplitudes The fixed ultrasound signal excitation parameters are constant.

6. The multi-acoustic-field based laser cladding layer stress regulation method according to claim 5, characterized in that: The propagation of ultrasonic waves in the ultrasonic vibrator in the cladding layer is not less than its near sound field.

7. The multi-acoustic-field based laser cladding layer stress regulation method according to claim 5, characterized in that: The minimum amplitude of the collected ultrasonic signal is not less than 20% of the maximum amplitude.

8. The multi-acoustic-field based laser cladding layer stress regulation method according to claim 5, characterized in that: using a plurality of ultrasonic vibrators, a plurality of different ultrasonic amplitudes are 0%, 10%, 50%, and 90% of the maximum amplitude.

9. The multi-acoustic-field based laser cladding layer stress regulation method of claim 5, wherein: The thickness of the laser cladding layer is between 0.5-6mm.

10. The multi-acoustic-field based laser cladding layer stress regulation method of claim 5, wherein: In step 2), the initial loading force is not greater than 5% of the yield strength of the laser layer static tensile specimen.

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