A test method for coating residual stress testing

Abstract

The application provides a test method for coating residual stress test, aiming at the particularity of the coating and the problems existing in the actual detection, studies the component composition and phase analysis of the coating, and establishes a test method for testing the residual stress of the coating by using different X-ray diffraction emission sources. Therefore, in the residual stress test of the coating, in addition to the basic preparation work including the component analysis and the phase analysis, the 2theta angle conversion between different ray sources is carried out according to the Bragg law, that is, the diffraction characteristics of different ray sources, and then the X-ray stress constant is further calculated, the residual stress calculation formula is introduced, and the residual stress database is established. The application has the advantages that: aiming at the component composition and phase analysis of the coating, the physical characteristics of different emission ray sources are used to calculate the residual stress value, the test demand of the X-ray diffractometer can be flexibly met, the residual stress test of the coating with different components can be met, and the practical value is great.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metallurgy, in particular to a test method for coating residual stress testing. BACKGROUND

[0002] The coating and the metal material are quite different in composition, organization and performance, and have special internal structural characteristics such as special holes, oxides, unmelted particles, microcracks and layered anisotropy, rough surface, and complex chemical composition with non-metallic chemical elements. Therefore, the test method for coating residual stress testing is more complex. The residual stress of the metal material can be detected by the X-ray diffraction method of the standard method, while the residual stress of the coating first needs to know the composition and phase analysis, and then select the best test method combined with the characteristics of the emission source, or solve the calculation through the emission source conversion, and then obtain the measured value. SUMMARY

[0003] The purpose of the present application is to solve the detection problem of coating residual stress testing, establish a new test method, fill the detection blank in this aspect, meet the detection needs of scientific research and production, and particularly provide a test method for coating residual stress testing.

[0004] The present application provides a test method for coating residual stress testing. In view of the particularity of the coating and the problems existing in the actual detection, the composition and phase analysis of the coating are researched according to the GJB10056 standard, and the test method for testing the residual stress of the coating by using different X-ray diffraction emission sources is established. Therefore, in the residual stress testing of the coating, in addition to the basic preparation work including composition analysis and phase analysis, the 2θ angle conversion between different radiation sources according to the Bragg law, that is, the diffraction characteristics of different radiation sources, and the further calculation of the X-ray stress constant, the introduction of the residual stress calculation formula, and the establishment of the residual stress database are also needed, which are the key technologies for testing the residual stress of the coating.

[0005] Detailed description of the technical scheme:

[0006] a. Coating composition determination

[0007] The coating composition determination is determined by energy spectrum method, and the composition proportion of each element in the composition is determined.

[0008] b. Coating phase analysis

[0009] The coating phase analysis is determined by X-ray diffractometer, and the phase composition existing in the coating and the proportion are determined. The diffraction signal with strong signal is selected as the first phase analysis.

[0010] c. Coating residual stress determination

[0011] The X-ray diffraction method is used, the relationship between diffraction angle 2θ of different target sources and micro-crystal spacing d is converted based on Bragg's law: 2d Sinθ=nλ, and then according to Bragg's law and elastic theory, the stress value σ is proportional to the slope M of 2θ changing with Sin2ψ, and the macro stress, i.e. residual stress, can be derived from the lattice strain measured by the X-ray method.

[0012] σ=K·M;

[0013]

[0014] d, application of Mn, Cr, Ti emission target source, conversion of residual stress value

[0015] According to Bragg's law: 2d Sinθ=nλ, the Sinθ values of different target sources including Mn target, Cr target and Ti target are converted according to d and λ obtained by phase analysis, and then the corresponding 2θ is obtained, the X-ray stress constant is calculated, the residual stress formula is introduced, the database is established, and the residual stress value of the test is obtained.

[0016] Coating residual stress test process:

[0017] The substrate test piece (GH4169 material) is prepared, the specification is 15*1.5*70mm, the substrate test piece is sandblasted, the atmospheric plasma spraying coating is carried out on the substrate test piece, the thickness is 1.5mm, the coating test piece is cut and prepared, the coating composition is determined, the coating phase analysis is carried out, the K value is calculated, the M value is calculated, the Sinθ values of different emission sources are calculated, the 2θ is calculated, and the stress value σ is calculated by using Bragg's law and elastic theory.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] The test method for coating residual stress test provided by the present application is used for the composition and phase analysis of the coating, and the physical characteristics of different emission ray sources are used to calculate the residual stress value, so that the test demand of the X-ray diffractometer can be flexibly met, the residual stress test of the coating with different compositions can be met, and the practical value is great. DETAILED DESCRIPTION

[0020] The present application will be further explained in combination with specific implementation schemes, but is not limited to the present application.

[0021] The embodiment provides a test method for coating residual stress test, aiming at the particularity of the coating and the problems existing in actual detection, referring to the GJB10056 standard, researching the component composition and phase analysis of the coating, and establishing a test method for testing the residual stress of the coating by using different X-ray diffraction emission sources. Therefore, in the residual stress test of the coating, in addition to the basic preparation work including the component analysis and the phase analysis, the 2θ angle conversion between different ray sources is also carried out according to the Bragg law, that is, the diffraction characteristics of different ray sources, and then the X-ray stress constant is further calculated, the residual stress calculation formula is introduced, the residual stress database is established, which is a key technology for testing the residual stress of the coating.

[0022] Technical scheme detailed description:

[0023] a. Coating component determination

[0024] The coating component determination is determined by using the energy spectrum method, and the component proportion of each element in the component is determined.

[0025] b. Coating phase analysis

[0026] The coating phase analysis is determined by using the X-ray diffractometer, and the phase composition existing in the coating and the proportion are determined, and the diffraction signal strong is selected as the first phase analysis.

[0027] c. Coating residual stress determination

[0028] The X-ray diffraction method is adopted, the relationship between the diffraction angle 2θ of different target sources and the micro-crystal face spacing d is established based on the Bragg law: 2d Sinθ = nλ, and then the stress value σ is proportional to the slope M of 2θ changing with Sin2ψ according to the Bragg law and the elastic theory, and the macro stress, that is, the residual stress, can be derived from the lattice strain measured by the X-ray method.

[0029] σ = K·M

[0030]

[0031] d. Application of Mn, Cr and Ti emission target source to convert residual stress value

[0032] According to the Bragg law: 2d Sinθ = nλ, the Sinθ values of different target sources including the Mn target, the Cr target and the Ti target are converted according to d and λ obtained from the phase analysis, and then the corresponding 2θ is obtained, the X-ray stress constant is calculated, the residual stress formula is introduced, the database is established, and the residual stress value of the test is obtained.

[0033] Coating residual stress test process:

[0034] A base test piece (GH4169 material) with a specification of 15*1.5*70mm is prepared, the base test piece is sandblasted, an atmospheric plasma spraying coating with a thickness of 1.5mm is formed on the base test piece, a coated test piece is cut and prepared, a coating composition is determined, a coating phase analysis is performed, a K value is calculated, an M value is calculated, different emission source Sinθ values are calculated, 2θ values are calculated, a stress value σ is calculated by using Bragg's law and elastic theory.

[0035] The details of the application are as follows.

[0036] Although embodiments of the present application have been shown and described, it would be appreciated by those of ordinary skill in the art that various changes, modifications, alternatives, and variations can be made thereto without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A test method for testing residual stress in coatings, characterized in that: The process is as follows: a. Coating composition determination; The composition of the coating was determined by energy dispersive spectroscopy (EDS) to determine the proportion of each element in the composition. b. Coating phase analysis; X-ray diffraction was used for phase analysis of the coating to determine which phases were present in the coating and what their proportions were. The phases with the strongest diffraction signals were selected as the primary phases for analysis. c. Measurement of residual stress in the coating; Using X-ray diffraction, based on Bragg's law: 2d Sinθ=n λ, the relationship between the diffraction angle 2θ and the microscopic interplanar spacing d for different target sources is established. Then, according to Bragg's law and elasticity theory, it can be derived that the stress value σ is proportional to the slope of 2θ as a function of Sin2φ. M The macroscopic stress, i.e. the residual stress, can be deduced from the lattice strain measured by X-ray diffraction. Where: σ=K· M ; d. Using Mn, Cr, and Ti emission targets, calculate the residual stress values; Based on Bragg's law: 2d Sinθ=nλ, the sinθ values ​​of different target sources, including Mn target, Cr target, and Ti target, are converted according to the d and λ obtained from the phase analysis. Then, the corresponding 2θ is obtained, the X-ray stress constant is calculated, the residual stress formula is imported, a database is established, and the test residual stress values ​​are obtained.

2. The test method for testing residual stress in coatings according to claim 1, characterized in that: The process for testing the residual stress value is as follows: a substrate specimen is prepared, made of GH4169 material, with dimensions of 15*1.5*70mm. The substrate specimen is sandblasted, and an atmospheric plasma spray coating with a thickness of 1.5mm is applied to the substrate specimen. The coated specimen is then cut and prepared. The coating composition is determined, the coating phase is analyzed, the K value is calculated, the M value is calculated, the Sinθ value for different emission sources is calculated, 2θ is calculated, and the stress value σ is calculated using Bragg's law and elasticity theory.

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