Method for analyzing highest temperature experienced by 304 stainless steel and workpiece thereof

Abstract

The invention provides a method for analyzing the highest temperature experienced by 304 stainless steel and a workpiece thereof. 304 stainless steel and a workpiece thereof work in an air atmosphere and a high-temperature environment, a layer of extremely thin and compact colorless transparent oxide film is generated on the surface through high-temperature oxidation, an interference color is displayed, and the color of the interference color is related to the thickness of the oxide film. After 304 stainless steel and a workpiece thereof are subjected to high-temperature oxidation for a certain period of time, the thickness of an oxidation film is related to the highest temperature. The L * value and the a * value of the surface color of the 304 stainless steel and the workpiece thereof are measured by a spectrophotometer and substituted into the formula provided by the invention, and the highest temperature experienced by the 304 stainless steel and the workpiece thereof can be calculated. The method has the advantages that test preparation in the early stage is not needed; observation is not needed when 304 stainless steel and workpieces thereof work; a non-contact mode is adopted, and the surface of a tested object is not damaged.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material testing and analysis, and particularly relates to a method for analyzing the highest temperature experienced by 304 stainless steel and its components. Background Art

[0002] 304 stainless steel is a very commonly used chromium-nickel stainless steel, which has good corrosion resistance, heat resistance, low-temperature strength and mechanical properties. Its high-temperature performance is also relatively good, and it can usually be applied in the range of temperatures below 650°C.

[0003] After 304 stainless steel and its components are subjected to high-temperature action in an air atmosphere, their surfaces show a certain color. The reason for the high-temperature discoloration of 304 stainless steel is that oxidation occurs on the surface to form a colorless and transparent oxide film, and the change in the thickness of the oxide film causes interference colors. The oxidation color on the surface of 304 stainless steel is mainly related to its chemical composition, the highest temperature of high-temperature oxidation experienced, and time. Therefore, the highest temperature experienced during its operation in a high-temperature environment can be inferred by analyzing the oxidation color on the surface of 304 stainless steel. At present, in engineering, the working temperature experienced by 304 stainless steel parts can be obtained by methods such as thermocouples, infrared temperature measurement, and temperature indicating paint. However, the temperature measurement process is relatively complex, the cost is high, and it is necessary to arrange test conditions in advance. For some parts where it is inconvenient to place thermocouples and temperature indicating paint and cannot be directly observed during work, these methods are not applicable. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a method for analyzing the highest temperature experienced by 304 stainless steel and its components, so as to provide a method for analyzing the highest temperature experienced by 304 stainless steel and its components in an air atmosphere.

[0005] Another purpose of the present invention is to provide a method for analyzing the highest temperature experienced by 304 stainless steel and its components, so as to provide a method for analyzing the highest temperature experienced by 304 stainless steel and its components that are inconvenient to place thermocouples and temperature indicating paint and cannot be directly observed during work.

[0006] The third purpose of the present invention is to provide a method for analyzing the highest temperature experienced by 304 stainless steel and its components, which can analyze the highest temperature experienced by them through the oxidation color on the surface of 304 stainless steel and its components.

[0007] The purpose of the present invention is achieved as follows. It relates to a method for analyzing the highest temperature experienced by 304 stainless steel and its components, and is characterized by including the following processes: 1) Select that the oxide film on the surface of 304 stainless steel is a colorless and transparent film, which can produce the interference effect of visible light; 2) Irradiate the surface of the oxide film with white light parallel light, and the parallel light includes incident light A and incident light B; 3) Part of the incident light undergoes specular reflection on the upper surface of the oxide film, and part of it generates refracted light through the oxide film. The refracted light is reflected back at the boundary surface of the stainless steel substrate to generate reflected light; 4) The optical path of incident light A in the 304 stainless steel oxide film is the same as that of incident light B. There is a certain interval between incident light B and incident light A, and this interval causes the reflected light and incident light B to form interference light in the oxide film; 5) The interference light forms an interference fringe film at the oxide film. After interference, which color of the white light parallel light waves is strengthened depends on the thickness of the oxide film. When the white light parallel light passes through an oxide film of a certain thickness, the vibration of the light waves of a certain wavelength is strengthened, and the oxide film presents the color of the light corresponding to that wavelength; Use a spectro-tester to perform chromaticity tests on the surface of the 304 stainless steel and its parts after high-temperature oxidation treatment; Obtain the highest temperature experienced by the 304 stainless steel and its parts.

[0008] The step 5) is achieved in the following way: Use a spectro-tester to perform chromaticity tests on the surface of the 304 stainless steel and its parts after high-temperature oxidation treatment, and obtain L* and a*. The L* value decreases as the high-temperature oxidation time increases, and the higher the oxidation temperature, the lower the L* value; The a* value increases as the high-temperature oxidation time increases, and the higher the oxidation temperature, the higher the a* value; The obtained L* values are successively: the curve of the L* value of the 304 stainless steel surface changing with time at 300 °C, the curve of the L* value of the 304 stainless steel surface changing with time at 400 °C, the curve of the L* value of the 304 stainless steel surface changing with time at 500 °C, the curve of the L* value of the 304 stainless steel surface changing with time at 600 °C, the curve of the L* value of the 304 stainless steel surface changing with time at 700 °C; The obtained a* values are successively the curve of the a* value of the 304 stainless steel surface changing with time at 300 °C, the curve of the a* value of the 304 stainless steel surface changing with time at 400 °C, the curve of the a* value of the 304 stainless steel surface changing with time at 500 °C, the curve of the a* value of the 304 stainless steel surface changing with time at 600 °C, the curve of the a* value of the 304 stainless steel surface changing with time at 700 °C; Derive the relationship between temperature and L*, a* values based on the L* and a* values. The relationship between the highest temperature T and the L* value is as follows in mathematical expression: T = k1(L*)³ + k2(L*) 2 + k3L* + k4 ……(1) In the formula, T is the highest temperature experienced by the 304 stainless steel and its parts; L* is the L* value measured by the spectro-tester on the surface of the 304 stainless steel and its parts; k1, k2, k3, k4 are coefficients; The relationship between the highest temperature T and the a* value. The mathematical expression of the relationship between the highest temperature T and the a* value is as follows: T = k1(a*) 3 + k2(a*) 2 + k3(a*) + k4……(2) Substituting the L* value into Equation 1 can obtain the highest temperature experienced by the 304 stainless steel and its parts; substituting the a* value into Equation 2 can obtain the highest temperature experienced by the 304 stainless steel and its parts.

[0009] The advantages of the present invention are as follows: 1. The method disclosed in the present invention analyzes the highest temperature experienced by the surface state of 304 stainless steel and its parts that have experienced high temperature, and does not require test preparation before experiencing high temperature; 2. The method disclosed in the present invention analyzes the highest temperature experienced by the surface state of 304 stainless steel and its parts that have experienced high temperature, and does not require observation during its operation, with a wide range of applications; 3. The method disclosed in the present invention analyzes the highest temperature experienced by the surface state of 304 stainless steel and its parts that have experienced high temperature. The analysis process is non-contact and does not damage its surface. Description of the Drawings

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present invention or the existing design methods, the following will briefly introduce the drawings required in the description of the embodiments or the existing design methods: Figure 1 It is a schematic diagram of the principle of interference color of the oxide film; Figure 2 It is the change of the color L* value during the high-temperature oxidation of 304 stainless steel; Figure 3 It is the change of the color L* value during the high-temperature oxidation of 304 stainless steel; Figure 4 It is the relationship between the highest temperature T experienced by 304 stainless steel and its parts and the L* value: Figure 5 It is the highest temperature corresponding to the color a* value after the high-temperature oxidation of 304 stainless steel.

[0011] In the figure, 101 is incident light A; 102 is incident light B; 103 is refracted light; 104 is reflected light; 105 is interference light; 106 is incident normal; 107 is oxide film; 108 is stainless steel substrate; 201 is the curve of the L* value of the 304 stainless steel surface changing with time at 300 °C; 202 is the curve of the L* value of the 304 stainless steel surface changing with time at 400 °C; 203 is the curve of the L* value of the 304 stainless steel surface changing with time at 500 °C; 204 is the curve of the L* value of the 304 stainless steel surface changing with time at 600 °C; 205 is the curve of the L* value of the 304 stainless steel surface changing with time at 700 °C; 301 is the curve of the a* value of the 304 stainless steel surface changing with time at 300 °C; 302 is the curve of the a* value of the 304 stainless steel surface changing with time at 400 °C; 303 is the curve of the a* value of the 304 stainless steel surface changing with time at 500 °C; 304 is the curve of the a* value of the 304 stainless steel surface changing with time at 600 °C; 305 is the curve of the a* value of the 304 stainless steel surface changing with time at 700 °C; 401 is the curve of the highest heating temperature corresponding to the L* value of the 304 stainless steel surface after high-temperature oxidation for a certain time; 501 is the curve of the highest heating temperature corresponding to the a* value of the 304 stainless steel surface after high-temperature oxidation for a certain time. Detailed implementation manners

[0012] The following will describe in detail the implementation manners of the present invention in conjunction with the accompanying drawings and embodiments, so as to fully understand how the present invention uses technical means to solve technical problems and achieve the implementation process of technical effects and implement accordingly. It should be noted that as long as there is no conflict, the various embodiments in the present invention and the various features in each embodiment can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

[0013] At the same time, in the following description, many specific details are set forth for the purpose of explanation to provide a thorough understanding of the embodiments of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without these specific details or in the specific manners described herein.

[0014] As Figure 1 shown, the present invention relates to a method for analyzing the highest temperature experienced by 304 stainless steel and its components, which is characterized in that: the oxide film selected on the 304 stainless steel surface is a colorless and transparent film that can produce visible light interference effects; its optical interference principle is as Figure 1 shown, when white light parallel light irradiates the surface of the oxide film 107, the parallel light includes incident light A 101 and incident light B 102. A part of incident light A 101 undergoes specular reflection on the upper surface of the oxide film 107, and a part generates refracted light 103 at the incident normal 106 through the oxide film 107. The refracted light 103 is reflected back at the boundary surface of the stainless steel substrate 108 to generate reflected light 104; The incident light B102 has the same optical path as the incident light A101 on the 304 stainless steel oxide film 107. There is a certain interval between the incident light B102 and the incident light A101. This interval causes the reflected light 104 and the reflected light 104 of the incident light B102 undergoing specular reflection on the oxide film 107 to form an interference light 105. The interference light 105 forms an interference fringe film at the oxide film 107. After interference, which color of light wave in the white parallel light is enhanced depends on the thickness of the oxide film. When the white parallel light passes through an oxide film of a certain thickness, the light wave of a certain wavelength vibrates strongly, and the oxide film presents the color of the light corresponding to that wavelength. Use a spectro-tester to conduct chromaticity tests on the surface of 304 stainless steel and its parts after high-temperature oxidation treatment. For the color change, refer to Figure 2 and Figure 3 , The L* value decreases as the high-temperature oxidation time increases, and then the decreasing amplitude slows down and remains stable after a certain time. The higher the oxidation temperature, the lower the L* value; The a* value increases as the high-temperature oxidation time increases, and then the increasing amplitude slows down and remains stable after a certain time. The higher the oxidation temperature, the higher the a* value; Figure 2 In

[0015] Figure 3 the L* values are as follows: the curve 201 of the L* value change with time on the surface of 304 stainless steel at 300 °C, the curve 202 of the L* value change with time on the surface of 304 stainless steel at 400 °C, the curve 203 of the L* value change with time on the surface of 304 stainless steel at 500 °C, the curve 204 of the L* value change with time on the surface of 304 stainless steel at 600 °C, and the curve 205 of the L* value change with time on the surface of 304 stainless steel at 700 °C. The lower the L* value, the higher the maximum temperature experienced by 304 stainless steel and its parts. The different high-temperature oxidation temperatures experienced by 304 stainless steel and its parts result in different thicknesses of the surface oxide film and different interference colors. The L* value and a* value measured by a spectro-tester are also different. According to this rule, a method for analyzing the maximum temperature experienced by applying the high-temperature oxidation color of 304 stainless steel and its parts can be given. The specific steps are as follows: According to Figure 2 、Figure 3 Obtain the L* value and a* value of the surface color of stainless steel after high-temperature oxidation at different temperatures for a certain time. Based on the L* value and a* value, deduce the relationship between temperature and L* value, a* value, as follows Figure 4 、 Figure 5 shown Figure 4 In [reference], curve 401 shows the L* value of the surface of 304 stainless steel after high-temperature oxidation for a certain time corresponding to the highest heating temperature. The lower the L* value, the higher the highest temperature experienced by 304 stainless steel and its parts Figure 5 In [reference], curve 501 shows the a* value of the surface of 304 stainless steel after high-temperature oxidation for a certain time corresponding to the highest heating temperature. The higher the a* value, the higher the highest temperature experienced by 304 stainless steel and its parts

[0016] The specific steps are as follows From Figure 4 The relationship between the highest temperature T experienced by 304 stainless steel and its parts and the L* value can be summarized. The mathematical expression of the relationship is as follows T = k1(L*)³ + k2(L*) 2 + k3L* + k4 ……(1) In the formula, T is the highest temperature experienced by 304 stainless steel and its parts; L* is the L* value of the surface of 304 stainless steel and its parts measured by a spectro-testing instrument; k1, k2, k3, k4 are coefficients

[0017] From Figure 5 The relationship between the highest temperature T experienced by 304 stainless steel and its parts and the a* value can be summarized. The mathematical expression of the relationship between the highest temperature T and the a* value is as follows T = k1(a*) 3 + k2(a*) 2 + k3(a*) + k4……(2) In the formula, T is the highest temperature experienced by 304 stainless steel and its parts; a* is the a* value of the surface of 304 stainless steel and its parts measured by a spectro-testing instrument; k1, k2, k3, k4 are coefficients

[0018] When the 304 stainless steel and its parts to be analyzed are subjected to high-temperature oxidation in an air atmosphere for a certain time, use a spectro-testing instrument to perform colorimetric testing on its surface, and record the L*, a* values measured by SCI Substitute the L* value into formula 1 to obtain the highest temperature experienced by the 304 stainless steel and its parts; substitute the a* value into formula 2 to obtain the highest temperature experienced by the 304 stainless steel and its parts

[0019] Applying the above principle, two embodiments are given below to illustrate the analysis method of the present invention Example 1

[0020] This example discloses a method for analyzing the highest temperature experienced by 304 stainless steel and its parts, and its principle and law are as follows Figure 4 , that is, the lower the L* value, the higher the highest temperature experienced by 304 stainless steel and its parts. Summarize its law as follows T = k1(L*)³ + k2(L*) 2 + k3L* + k4 ……(1) In the formula T is the highest temperature experienced by 304 stainless steel and its parts L* is the L* value measured on the surface of 304 stainless steel and its parts by a spectrophotometer k1, k2, k3, k4 are coefficients For the 304 stainless steel and its parts to be analyzed after high-temperature oxidation in an air atmosphere for a certain period of time, use a spectrophotometer to perform colorimetric tests on its surface, measure the L* value, and apply formula (1) to obtain the highest temperature experienced by the 304 stainless steel and its parts as T = k1(L*)³ + k2(L*) 2 + k3L* + k4

[0021] The preferred numerical values of the coefficients in the formula are as follows k1 = -1.6585×10 -2 ; k2 = 2.3855 k3 = -117.6304 k4 = 2619.8094 Example 2

[0022] This example discloses a method for analyzing the highest temperature experienced by 304 stainless steel and its parts, and its principle and law are as follows Figure 5 , that is, the higher the a* value, the higher the highest temperature experienced by 304 stainless steel and its parts. Summarize its law as follows T = k1(a*) 3 + k2(a*) 2 + k3(a*) + k4……(2) In the formula T is the highest temperature experienced by 304 stainless steel and its parts a* is the a* value measured on the surface of 304 stainless steel and its parts by a spectrophotometer k1, k2, k3, k4 are coefficients For the 304 stainless steel and its fabricated parts to be analyzed after high-temperature oxidation in an air atmosphere for a certain period of time, use a spectro-testing instrument to conduct chromaticity testing on its surface, measure the a* value, and apply Equation 2 to obtain the maximum temperature experienced by the 304 stainless steel and its fabricated parts as follows: T = k1(a*) 3 + k2(a*) 2 + k3(a*) + k4.

[0023] The preferred numerical values of the coefficients in the formula are as follows: k1 = 6.1406×10 -2 ; k2 = -2.7541; k3 = 55.0889; k4 = 267.4303.

[0024] The principle of the present invention is: in an air atmosphere, a very thin and dense oxide film will form on the surface of 304 stainless steel and its fabricated parts in a high-temperature environment. The higher the temperature, the faster the oxidation rate, and the thicker the oxide film formed. Under the condition of unchanged environmental conditions, when the thickness of the oxide film reaches a certain level, metal elements cannot penetrate this thick oxide film, and the oxidation reaction rate tends to stagnate, and the film layer no longer thickens; therefore, after the oxidation process reaches a certain period of time, the thickness of the oxide film on the surface of 304 stainless steel and its fabricated parts is related to the temperature of its environment.

[0025] The above is only a schematic specific implementation manner of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principle of the present invention, as well as applications to fields not mentioned in the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A method for analyzing the highest temperature experienced by 304 stainless steel and its components, characterized in that: It includes the following processes: 1) The oxide film on the surface of 304 stainless steel is a colorless and transparent film, which can produce the interference effect of visible light; 2) Irradiate the surface of the oxide film (107) with white parallel light, and the parallel light includes incident light A (101) and incident light B (102): 3) Part of incident light A (101) undergoes specular reflection on the upper surface of the oxide film (107), and part of it generates refracted light (103) through the oxide film (107). The refracted light (103) reflects back at the boundary with the stainless steel substrate (108) to generate reflected light (104); 4) The optical path of incident light B (102) in the 304 stainless steel oxide film (107) is the same as that of incident light A (101). There is a certain interval between incident light B (102) and incident light A (101), and the interval is such that the reflected light (104) and incident light B (102) form interference light (105) in the oxide film (107); 5) The interference light (105) forms an interference fringe film at the oxide film (107). After interference, which color of light wave in the white parallel light is enhanced depends on the thickness of the oxide film. When the white parallel light passes through an oxide film of a certain thickness, the light wave of a certain wavelength vibrates strongly, and the oxide film presents the color of the light corresponding to that wavelength; Use a spectro-tester to perform chromaticity tests on the surface of 304 stainless steel and its parts after high-temperature oxidation treatment; Obtain the highest temperature experienced by the 304 stainless steel and its parts.

2. A method for analyzing the highest temperature experienced by 304 stainless steel and its components according to claim 1, characterized in that: The step 5) is achieved in the following way Use a spectro-tester to perform chromaticity tests on the surface of 304 stainless steel and its parts after high-temperature oxidation treatment, and obtain L* and a*. The L* value decreases as the high-temperature oxidation time increases, and the higher the oxidation temperature, the lower the L* value; The a* value increases as the high-temperature oxidation time increases, and the higher the oxidation temperature, the higher the a* value; The obtained L* values are successively: the curve of the L* value of the 304 stainless steel surface changing with time at 300 °C (201), the curve of the L* value of the 304 stainless steel surface changing with time at 400 °C (202), the curve of the L* value of the 304 stainless steel surface changing with time at 500 °C (203), the curve of the L* value of the 304 stainless steel surface changing with time at 600 °C (204), the curve of the L* value of the 304 stainless steel surface changing with time at 700 °C (205); The obtained a* values are successively the curve of the a* value of the 304 stainless steel surface changing with time at 300 °C (301), the curve of the a* value of the 304 stainless steel surface changing with time at 400 °C (302), the curve of the a* value of the 304 stainless steel surface changing with time at 500 °C (303); the curve of the a* value of the 304 stainless steel surface changing with time at 600 °C (304), the curve of the a* value of the 304 stainless steel surface changing with time at 700 °C (305); Derive the relationship between temperature and L*, a* values based on the L* value and a* value. The relationship between the highest temperature T and the L* value is as follows in mathematical expression: T = k1(L*)³ + k2(L*) 2 + k3L* + k4 ……(1) Wherein, T is the highest temperature experienced by 304 stainless steel and its components; L* is the L* value measured on the surface of 304 stainless steel and its components by a spectro-testing instrument; k1, k2, k3, and k4 are coefficients; The relationship between the highest temperature T and the a* value, and the mathematical expression of the relationship between the highest temperature T and the a* value is as follows: T = k1(a*) 3 + k2(a*) 2 + k3(a*) + k4……(2) Substituting the L* value into Equation 1 can obtain the highest temperature experienced by the 304 stainless steel and its components; substituting the a* value into Equation 2 can obtain the highest temperature experienced by the 304 stainless steel and its components.

Images