Laser cladding layer stress regulation and control method based on multiple sound fields

Abstract

The invention discloses a laser cladding layer stress regulation and control method based on multiple sound fields, which comprises the following steps of: establishing a quantitative relational expression between an ultrasonic signal amplitude and an ultrasonic amplitude, and loading a plurality of laser layer static load tensile samples under different ultrasonic amplitudes step by step; establishing a corresponding relational expression between the propagation time difference and the loading load and quantitative expressions of a plurality of calibrated ultrasonic acoustic elastic coefficients and a plurality of different ultrasonic amplitudes; the ultrasonic signal amplitude of the laser cladding layer to be regulated and controlled is collected to obtain the ultrasonic amplitude and the ultrasonic acoustic elastic coefficient, the ultrasonic amplitude and the ultrasonic acoustic elastic coefficient are compared with a plurality of calibrated ultrasonic acoustic elastic coefficients, and the optimal ultrasonic amplitude corresponding to the ultrasonic acoustic elastic coefficient with the minimum error absolute value is obtained. Taking the critical refraction longitudinal wave signal which has the optimal ultrasonic amplitude and is not loaded as a reference signal, calculating a time difference between the ultrasonic signal and the reference signal, and obtaining a stress value; according to the method, mapping correlation among ultrasonic amplitude, ultrasonic acoustic elastic coefficient and stress is realized, and the stress of the laser cladding layer is eliminated by controlling ultrasonic vibration energy.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrasonic application, and specifically relates to an ultrasonic technology that can quickly and non-destructively achieve coating stress regulation. Background Art

[0002] Laser cladding technology has attracted widespread attention in the field of mechanical equipment remanufacturing. Relevant studies have shown that stress is one of the key factors affecting the quality of remanufactured laser cladding layers and even laser cladding remanufactured products. Therefore, it is extremely important to explore and develop technical methods that can achieve stress regulation of laser cladding layers. At present, the technical methods for stress regulation of laser cladding layers are mainly concentrated in the following three aspects: ① Optimization of laser cladding process; ② Research and development of new equipment and methods for laser cladding; ③ Research and development of new materials for laser cladding. Although the above methods have achieved the control of laser cladding layer stress to a certain extent, there are still obvious problems: One of the characteristics of laser cladding is the fast cooling rate, which causes the directional solidification of the organization and the induced stress is difficult to eliminate. At the same time, the above control method not only requires repeated experiments, but also is affected by random factors in the laser cladding process, making it difficult to achieve the expected control of laser cladding layer stress.

[0003] Ultrasonic vibration is a type of power ultrasound, which is a technical method that changes certain states of physical properties through ultrasonic energy. It has the advantages of convenience, controllability and easy application. Ultrasonic stress evaluation technology is a stress evaluation technology proposed based on the ultrasonic acoustic elastic effect in solid media. It has the advantages of non-destructive, rapid, convenient and harmless, and is used 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 "A method for quickly and non-destructively achieving stress regulation of cladding layer based on ultrasonic technology" is based on ultrasonic acoustic elasticity theory. Combined with the static load tensile calibration method, the ultrasonic acoustic elastic formula of the cladding layer under tension and compression is established, and the cladding layer samples with different compressive stress states are prepared by ultrasonic impact technology. The ultrasonic time delay caused by stress is used as the "intermediate parameter" to establish the corresponding relationship between stress and ultrasonic impact coverage, thereby realizing non-destructive and rapid regulation of cladding layer stress. However, this method has the following defects: since it is based on sampling under a single ultrasonic amplitude and the ultrasonic signals of the cladding layer samples before / after impact are collected, the variables in the cladding process are not detected. In the cladding process, the cooling rate is fast, the stress changes induced by the directional solidification of the structure are large, and there are also random factors. Therefore, the method is not accurate in controlling the stress of the cladding layer during the cladding process. Summary of the invention

[0004] In view of the problem of low precision in the current stress control of laser cladding layers, the present invention proposes a stress control method for laser cladding layers based on multi-sound fields, which can accurately, quickly and non-destructively control the stress of laser cladding layers.

[0005] To achieve the above object, the technical solution adopted by the laser cladding layer stress control method based on multi-sound field of the present invention comprises the following steps:

[0006] Step 1): Multiple groups of ultrasonic vibrators are used to apply multiple different ultrasonic amplitudes during the laser cladding layer preparation process. Prepare a plurality of corresponding laser cladding layer samples, and extract the ultrasonic signal amplitudes of the plurality of laser cladding layer samples Establishing the ultrasonic signal amplitude With ultrasonic amplitude Quantitative relationship of

[0007] Step 2): Processing the multiple different ultrasonic amplitudes The method comprises the following steps: loading the plurality of laser layer static load tensile specimens step by step, collecting the propagation time difference Δt of the ultrasonic signals in turn, establishing a corresponding relationship between the propagation time difference Δt and the loading load σ; extracting a plurality of calibrated ultrasonic acoustoelastic coefficients k from the corresponding relationship, establishing a relationship between the plurality of calibrated ultrasonic acoustoelastic coefficients k and a plurality of different ultrasonic amplitudes; Quantitative expression of

[0008] Step 3): Collect the ultrasonic signal amplitude A' of the laser cladding layer to be regulated, first use the ultrasonic signal amplitude described in step 1) With ultrasonic amplitude The ultrasonic amplitude z′ is obtained by using the quantitative relationship of the ultrasonic amplitude z′; and then based on the ultrasonic amplitude z′, the multiple calibrated ultrasonic acoustic elastic coefficients k described in step 2) and multiple different ultrasonic amplitudes are used. The quantitative expression of the ultrasonic acoustoelastic coefficient k′ of the laser cladding layer to be controlled is obtained;

[0009] Step 4): Compare the ultrasonic acoustoelastic coefficient k′ with the multiple calibrated ultrasonic acoustoelastic coefficients k to obtain the optimal ultrasonic amplitude corresponding to the ultrasonic acoustoelastic coefficient k with the smallest absolute error between the two, and use the critical refracted longitudinal wave signal of the laser cladding layer to be regulated when the optimal ultrasonic amplitude is used and not loaded as a reference signal;

[0010] Step 5): Calculate the time difference between the ultrasonic signal applied to the laser cladding layer to be regulated and the reference signal, and obtain 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 described in step 2).

[0011] The advantages of the present invention after adopting the above technical solution are:

[0012] 1. The present invention prepares multiple groups of coating samples with different ultrasonic amplitudes. First, the coating structure and stress state are changed by controlling the ultrasonic vibration amplitude (energy). The ultrasonic acoustoelastic coefficient calibration experiment is carried out based on the ultrasonic acoustoelasticity theory and combined with the static load tensile calibration method to obtain the corresponding relationship between the ultrasonic acoustoelastic coefficient and the ultrasonic amplitude. Finally, ultrasonic regulation of coating stress is achieved. This not only provides a non-destructive method for evaluating coating stress, but also provides a convenient and effective method for controlling coating stress. It has the advantages of being fast, convenient, safe and online.

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

[0014] (1) The method disclosed in the patent publication number CN111504530A is based on sampling under a single ultrasonic amplitude, while the present invention is based on sampling under multiple different ultrasonic amplitudes and during the cladding process.

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

[0016] (3) The method disclosed in the patent publication number CN111504530A is to sequentially collect ultrasonic signals of the cladding layer before impact and at different coverages, take the ultrasonic signal of the cladding layer sample before impact as the reference signal, and compare the ultrasonic signals of the cladding layer with different coverages after impact with the ultrasonic signal of the cladding layer before impact to obtain the time delay. The present invention sequentially collects ultrasonic signals during the ultrasonic process to obtain the propagation time difference.

[0017] (4) The method disclosed in the patent publication number CN111504530A is to fit the coverage and the time delay before and after the impact of the cladding layer to establish the relationship between the ultrasonic impact coverage and stress. The present invention obtains the stress value based on the corresponding relationship between the propagation time difference and the loading load.

[0018] It can be seen that the present invention uses the energy attenuation of ultrasonic signals induced by the laser cladding layer tissue and the ultrasonic propagation speed induced by the laser cladding layer stress as correlations to realize the mapping correlation between ultrasonic amplitude, ultrasonic acoustoelastic coefficient and stress, establishes a corresponding relationship between the ultrasonic evaluation of the laser cladding layer stress and the characteristic parameters of the ultrasonic vibration changing the laser cladding layer stress, realizes the elimination of the laser cladding layer stress by controlling the ultrasonic vibration energy, and integrates it with the ultrasonic evaluation of the laser cladding layer stress evaluation technology to form a stress closed-loop control, which is different from the open-loop control method disclosed in the patent publication number CN111504530A, thereby realizing the control of its tissue during the laser cladding process and realizing the non-destructive evaluation of the laser cladding layer stress.

[0019] 3. The present invention combines ultrasonic vibration and ultrasonic stress evaluation technology, that is, firstly, the stress state of the laser cladding process is changed by controlling the ultrasonic vibration energy; secondly, the actual stress is evaluated by ultrasonic waves; finally, the actual stress of the laser cladding layer to which ultrasonic vibration is applied is used to provide a basis and foundation for subsequent stress regulation, and provides technical support and theoretical basis for achieving stress control of the laser cladding layer. It can provide technical support for the quality and reliability evaluation of the laser cladding layer, and reduce or even avoid the hidden safety hazards of the remanufactured products in service. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a curve diagram showing the relationship between the ultrasonic wave amplitude and the critical refracted longitudinal wave receiving signal amplitude in an embodiment of the present invention;

[0021] Figure 2 4 is a curve diagram showing the relationship between the acoustoelastic coefficient of an ultrasonic signal and the ultrasonic amplitude in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention discloses a stress control method for a laser cladding layer based on multiple sound fields. A laser cladding method is used on a test bottom plate to prepare a coating of a certain thickness on its surface. The coating is a metal coating, including a metallurgical bonding coating and a non-metallurgical bonding coating. The coating thickness is between 0.5 and 6 mm, and the coating thickness error of the sample bottom plate is not greater than ±5%, and the ultrasonic detection depth error is also not greater than ±5%, and the coating roughness is not greater than Ra1.6. Multiple groups of ultrasonic vibrators of no less than 3 groups are used. According to the thickness of the bottom plate, the auxiliary devices of the multiple groups of ultrasonic vibrators are adjusted. By adjusting the auxiliary devices, all ultrasonic vibrators are ensured to have good contact with the bottom plate, the effect of ultrasonic vibration is ensured, and the ultrasonic waves of all ultrasonic vibrators are propagated in the coating no less than their near sound field. The amplitude range is optimized, and the ultrasonic signal excitation parameter M is adjusted based on the maximum and minimum values ​​of the ultrasonic energy signal (i.e., the ultrasonic signal amplitude of the received signal) attenuation, so as to ensure that the lowest amplitude of the ultrasonic signal is not less than 20% of the highest amplitude. Then, the ultrasonic signal excitation parameter M is fixed to be constant to ensure good and stable coupling between the ultrasonic probe and the coating surface.

[0023] During the laser cladding layer preparation process, multiple different ultrasonic amplitudes were applied to the test base plate. Changing the ultrasound amplitude Prepare different ultrasonic amplitudes Multiple laser cladding layer samples. At the same time, the ultrasonic mode for detection is selected as critical refracted longitudinal wave, the ultrasonic excitation energy parameters and propagation distance are fixed, and different ultrasonic amplitudes are applied to collect and extract Multiple ultrasonic signal amplitudes corresponding to multiple laser cladding layer samples For multiple ultrasound amplitudes and multiple ultrasonic signal amplitudes Perform fitting to establish the ultrasonic signal amplitude With ultrasonic amplitude The corresponding fitting relationship is obtained as follows: (1) The ultrasonic signal amplitude With ultrasonic amplitude The quantitative relationship of:

[0024]

[0025] Where: is the fitting coefficient.

[0026] According to the static tensile standard of metal materials at room temperature, processing at different ultrasonic amplitudes The laser layer static load tensile specimens were subjected to stress relief treatment by heat treatment method, and the stresses were measured at different ultrasonic amplitudes. The yield strength of the laser layer static load tensile specimen under the condition of . The highest loading load is set as the yield strength of the laser layer static load tensile specimen, and the ultrasonic signal of the laser layer static load tensile specimen when not loaded is defined as the reference signal, ensuring that the number of loaded loads is not less than 5 groups. Based on this, multiple laser layer static load tensile specimens are loaded step by step. After the load is stable, the propagation time difference Δt of the ultrasonic signals of multiple laser layer static load tensile specimens under the loads loaded step by step is collected in turn. The corresponding relationship between the propagation time difference Δt and the loading load σ is established using the following formula (2), which contains the calibrated ultrasonic acoustic elastic coefficient k:

[0027] △t=kσ+c (2)

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

[0029] Based on the corresponding relationship between the propagation time difference Δt and the loading load σ in formula (2), the calibrated ultrasonic acoustoelastic coefficient k is extracted, and the calibrated ultrasonic acoustoelastic coefficient k and different ultrasonic amplitudes are established. The corresponding relationship is obtained by fitting the values ​​that conform to the monotonic change law using the polynomial of the following formula (3), and then obtaining its quantitative expression;

[0030]

[0031] Where: d, e, f are fitting coefficients, is the ultrasonic amplitude.

[0032] For the laser cladding layer to be regulated, the same ultrasonic signal excitation parameter M is applied, the ultrasonic signal of the laser cladding layer to be regulated is collected, and its ultrasonic signal amplitude A′ is proposed and substituted into formula (1): Replaced by the ultrasonic signal amplitude A′ The ultrasonic amplitude z' corresponding to the ultrasonic signal amplitude A' is obtained.

[0033] Substituting the ultrasonic amplitude z′ into the calibrated ultrasonic acoustoelastic coefficient k and different ultrasonic amplitudes In the corresponding relationship (3), the different ultrasonic amplitudes z′ are replaced by The corresponding ultrasonic acoustoelastic coefficient k′ of the laser cladding layer to be regulated is obtained.

[0034] The ultrasonic acoustoelastic coefficient k′ of the laser cladding layer to be regulated is compared with multiple calibrated ultrasonic acoustoelastic coefficients k, and the ultrasonic acoustoelastic coefficient k with the smallest absolute value of error between the two is selected as the optimal ultrasonic acoustoelastic coefficient, and the optimal ultrasonic amplitude corresponding to the optimal ultrasonic acoustoelastic coefficient is obtained. The optimal ultrasonic amplitude corresponding to the optimal ultrasonic acoustoelastic coefficient is used as the ultrasonic amplitude applied to the laser cladding layer to be regulated, and then the critical refracted longitudinal wave signal of the optimal ultrasonic amplitude corresponding to the optimal ultrasonic acoustoelastic coefficient adopted by the laser cladding layer to be regulated and without loading is used as the reference signal A0.

[0035] The time difference △t′ between the ultrasonic signal with an amplitude of A′ applied to the laser cladding layer to be regulated and the reference signal A0 is calculated, and the time difference △t′ is substituted into the formula △t=kσ+c, where △t′ replaces △t. According to the corresponding relationship between the propagation time difference and the loading load, the stress value σ′ on the laser cladding layer to be regulated is obtained, thereby realizing the regulation of the stress of the laser cladding layer.

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

[0037] Example

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

[0039] Step 1: Select Q235 steel with a thickness of 20 mm as the base material of the test base plate, select laser cladding method as the coating preparation technology, and the cladding powder is Fe314 alloy powder. The main process parameters for preparing the laser cladding layer are: laser power of 1.7 kW, laser cladding rate of 3 mm / s, protective gas of argon, and lateral powder feeding.

[0040] Select the ultrasonic vibration mode in the form of longitudinal wave, place the ultrasonic vibrator horizontally, and make close contact with the side surface (thickness direction) of the Q235 steel plate. Use ultrasonic amplitudes of 0% (not applied), 10%, 50%, and 90% of the maximum amplitude ratio. Four Fe314 alloy laser cladding layer samples with a thickness of (1.2±0.15) mm were prepared by applying four different ultrasonic amplitudes of 0%, 10%, 50% and 90% of the maximum amplitude ratio respectively.

[0041] Step 2: Select the critical refracted longitudinal wave as the ultrasonic mode for detection, the center frequency of the ultrasonic probe is 2.5MHz, and the one-transmit-one-receive mode is adopted. The ultrasonic propagation distance between the two ultrasonic probes is 30mm (greater than the near-sound field distance). Fix the ultrasonic signal excitation parameters and coupling state, and collect 4 groups of different ultrasonic amplitudes in turn. The critical refracted longitudinal wave signals of the laser cladding layer have received signal amplitudes of 32%, 51%, 73% and 76% of the full screen respectively.

[0042] Step 3: Extract 4 groups of samples with different ultrasonic amplitudes Critical refracted longitudinal wave received signal amplitude of laser cladding layer They are 32mV, 51mV, 73mV and 76mV respectively, and their relationship with the ultrasonic amplitude is established. For the corresponding relationship between Figure 1 , use formula (1) to fit it and get the critical refracted longitudinal wave signal amplitude With ultrasonic amplitude The quantitative relationship (4):

[0043]

[0044] Step 4: According to the standard GB / T2002-228 metal material room temperature tensile test method, prepare and apply 4 different ultrasonic amplitudes Four laser layer static tensile specimens with an overall thickness (laser cladding layer + Q235 steel) of 3.0 mm were subjected to stress relief annealing by vacuum stress relief annealing. Based on this, the yield strengths of the four laser layer static tensile specimens were measured, which were 608 MPa, 652 MPa, 686 MPa and 635 MPa, respectively, and defined as the maximum loading stress.

[0045] The four laser layer static load tensile specimens were loaded step by step with 0MPa, 100MPa, 200MPa, 300MPa, 400MPa, 500MPa, 600MPa and the maximum loading stress, and the initial loading stress was not greater than 5% of its yield strength. The critical refraction longitudinal wave signals of the laser cladding layer of the four laser layer static load tensile specimens were collected during the step-by-step loading, and the time difference between the received signals was taken as the propagation time difference Δt, and then the corresponding relationship between the propagation time difference Δt and the loading load σ, i.e., stress, was established, as shown in formula (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 acoustoelastic k formulas are obtained. From formula (5), four different calibrated ultrasonic acoustoelastic k are obtained: 0.108, 0.163, 0.196, and 0.203, all in ns / MPa.

[0048] Step 5: Extract formula (5) by applying different ultrasonic amplitudes The ultrasonic acoustoelastic coefficient k of the laser cladding layer is calibrated and its relationship with the ultrasonic amplitude is established. For the corresponding relationship, see Figure 2 , the ultrasonic acoustoelastic coefficient and the ultrasonic amplitude used for fitting must satisfy monotonic change. Formula (3) is used to fit the values ​​that meet the monotonic change law, and then its quantitative expression is obtained, as shown in formula (6):

[0049]

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

[0051] Step 6: Apply the same ultrasonic parameters as those in step (2) to the laser cladding layer to be regulated, collect the critical refraction longitudinal wave signal of the laser cladding layer to be regulated, extract the ultrasonic signal amplitude A′ as 75.2 mv, and substitute 75.2 mv into formula (4): Right now The corresponding ultrasonic amplitude z' is calculated, and the ultrasonic amplitude z' is about 71% of the maximum amplitude ratio. Then, the ultrasonic amplitude z' is substituted into formula (6) to replace That is, equation (6) becomes: k′ = de·f z′ , so that the ultrasonic acoustoelastic coefficient k′ of the laser cladding layer to be regulated can be calculated, which is 0.201. Then, for the laser cladding layer to be regulated, formula (2) is specifically:

[0052] △t=0.201·σ (7)

[0053] Step 7, the ultrasonic acoustoelastic coefficient k′=0.201 of the laser cladding layer to be regulated is compared with the four different calibrated ultrasonic acoustoelastic coefficients k=0.108, 0.163, 0.196, and 0.203 obtained by the calibration test in formula (5), and the absolute value of the difference between the two is calculated. The minimum absolute value of the difference is 0.002=0.203-0.201, and the ultrasonic acoustoelastic coefficient k with the smallest absolute value of the error between the two is selected as the optimal ultrasonic acoustoelastic coefficient k=0.203. It can be seen from steps 1 and 4 that the optimal ultrasonic acoustoelastic coefficient k=0.203 corresponds to the ultrasonic amplitude of 90% of the maximum amplitude in step 1. Ultrasonic amplitude The ultrasonic acoustoelastic coefficient of the laser cladding layer sample is equal to or closest to the maximum amplitude of 90%, and then the ultrasonic amplitude is selected. The critical refracted longitudinal wave signal when the maximum amplitude is 90% and no load is applied is the reference signal A0.

[0054] Step eight, calculate the time difference △t' between the critical refracted longitudinal wave signal (amplitude A' is 75.2mv) 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, which is about 66ns. Substituting into formula (7), △t = 0.201·σ, the stress value σ' of the laser cladding layer to be regulated is calculated to be about 326Mpa, realizing the regulation of the stress of the laser cladding layer.

Claims

1. A method for regulating stress of a laser cladding layer based on multiple sound fields, characterized by comprising the following steps: Step 1): Multiple groups of ultrasonic vibrators are used to apply multiple different ultrasonic amplitudes during the laser cladding layer preparation process. Prepare a plurality of corresponding laser cladding layer samples, and extract the ultrasonic signal amplitudes of the plurality of laser cladding layer samples Establishing the ultrasonic signal amplitude With ultrasonic amplitude Quantitative relationship of Step 2): Processing the multiple different ultrasonic amplitudes The method comprises the following steps: loading the plurality of laser layer static load tensile specimens step by step, collecting the propagation time difference Δt of the ultrasonic signals in turn, establishing a corresponding relationship between the propagation time difference Δt and the loading load σ; extracting a plurality of calibrated ultrasonic acoustoelastic coefficients k from the corresponding relationship, establishing a relationship between the plurality of calibrated ultrasonic acoustoelastic coefficients k and a plurality of different ultrasonic amplitudes; Quantitative expression of ; Step 3): Collect the ultrasonic signal amplitude A' of the laser cladding layer to be regulated, first use the ultrasonic signal amplitude described in step 1) With ultrasonic amplitude The ultrasonic amplitude z′ is obtained by using the quantitative relationship of the ultrasonic amplitude z′; and then based on the ultrasonic amplitude z′, the multiple calibrated ultrasonic acoustic elastic coefficients k described in step 2) and multiple different ultrasonic amplitudes are used. The quantitative expression of the ultrasonic acoustoelastic coefficient k′ of the laser cladding layer to be controlled is obtained; Step 4): Compare the ultrasonic acoustoelastic coefficient k′ with the multiple calibrated ultrasonic acoustoelastic coefficients k to obtain the optimal ultrasonic amplitude corresponding to the ultrasonic acoustoelastic coefficient k with the smallest absolute error between the two, and use the critical refracted longitudinal wave signal of the laser cladding layer to be regulated when the optimal ultrasonic amplitude is used and not loaded as a reference signal; Step 5): Calculate the time difference between the ultrasonic signal applied to the laser cladding layer to be regulated and the reference signal, and obtain 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 described in step 2).

2. According to the method for controlling stress of laser cladding layer based on multi-sound field in claim 1, Its characteristics are: In step 1), the ultrasonic signal amplitude With ultrasonic amplitude The quantitative relationship is: is the fitting coefficient.

3. The method for controlling stress of laser cladding layer based on multi-sound fields according to claim 1, Its characteristics are: In step 2), the corresponding relationship between the propagation time difference Δt and the loading load σ is: Δt=kσ+c, where c is the fitting coefficient.

4. The method for controlling stress of laser cladding layer based on multi-sound fields according to claim 3, Its characteristics are: In step 2), the calibrated ultrasonic acoustoelastic coefficient k and different ultrasonic amplitudes The quantitative expression of is: d, e, and f are fitting coefficients.

5. The method for controlling stress of laser cladding layer based on multi-sound fields according to any one of claims 1 to 4, Its characteristics are: Apply multiple different ultrasound amplitudes When the ultrasonic signal excitation parameters are fixed, they remain constant.

6. The method for controlling stress of laser cladding layer based on multi-sound fields according to claim 5, Its characteristics are: The propagation of the ultrasonic wave of the ultrasonic vibrator in the cladding layer is not less than its near sound field.

7. The method for controlling stress of laser cladding layer based on multi-sound fields according to claim 5, Its characteristics are: The lowest amplitude of the collected ultrasonic signal shall not be less than 20% of the highest amplitude.

8. The method for controlling stress of laser cladding layer based on multi-sound fields according to claim 5, Its characteristics are: Use no less than 3 groups of ultrasonic vibrators with different ultrasonic amplitudes 0%, 10%, 50% and 90% of the maximum amplitude.

9. The method for controlling stress of laser cladding layer based on multi-sound fields according to claim 5, Its characteristics are: The thickness of the laser cladding layer is between 0.5 and 6 mm.

10. The method for controlling stress of laser cladding layer based on multi-sound fields according to claim 5, Its characteristics are: When loading step by step in step 2), the initial loading force is not greater than 5% of the yield strength of the static load tensile specimen of the laser layer.

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