A method of analyzing 304 stainless steel and its parts for maximum temperature experienced

Abstract

This invention provides a method for analyzing the highest temperature experienced by 304 stainless steel and its components. When 304 stainless steel and its components operate in an air atmosphere and high-temperature environment, their surface undergoes high-temperature oxidation, producing an extremely thin and dense colorless and transparent oxide film that exhibits interference colors. The color of these interference colors is related to the thickness of the oxide film. After a certain period of high-temperature oxidation, the thickness of the oxide film produced by the 304 stainless steel and its components is related to the highest temperature experienced. The L* and a* values ​​of the surface color of the 304 stainless steel and its components are measured using a spectrophotometer. These values ​​are then substituted into the formula provided in this invention to calculate the highest temperature experienced by the 304 stainless steel and its components. The advantages of this method are: no prior test preparation is required; no observation is needed while the 304 stainless steel and its components are in operation; and it is non-contact, thus not damaging the surface of the test object.

Description

Technical Field

[0001] This invention relates to the field of metal material testing and analysis technology, specifically to a method for analyzing the highest temperature experienced by 304 stainless steel and its components. Background Technology

[0002] 304 stainless steel is a widely used chromium-nickel stainless steel with good corrosion resistance, heat resistance, low-temperature strength and mechanical properties. It also has good high-temperature performance and can usually be used in the temperature range below 650℃.

[0003] When 304 stainless steel and its components are subjected to high temperatures in air, their surfaces exhibit a certain color. The reason for this high-temperature discoloration is the formation of a colorless, transparent oxide film through surface oxidation. Changes in the thickness of this oxide film cause interference colors. The surface oxidation color of 304 stainless steel is mainly related to its chemical composition, the highest temperature experienced during oxidation, and the duration of oxidation. Therefore, the highest temperature experienced during high-temperature operation can be inferred by analyzing the surface oxidation color of 304 stainless steel. Currently, in engineering, the operating temperature experienced by 304 stainless steel parts can be obtained using methods such as thermocouples, infrared thermometry, and temperature-indicating paint. However, the temperature measurement process is complex, costly, and requires pre-arrangement of test conditions. These methods are not applicable to parts where it is inconvenient to place thermocouples or temperature-indicating paint, or where direct observation is not possible during operation. Summary of the Invention

[0004] One of the objectives of this 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] The second objective of this 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, which are inconvenient to place thermocouples, temperature-indicating paint, or cannot be directly observed during operation.

[0006] The third objective of this 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 304 stainless steel and its components through the oxidation color on the surface.

[0007] The object of this invention is achieved by relating to a method for analyzing the highest temperature experienced by 304 stainless steel and its components, characterized by comprising the following process:

[0008] (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;

[0009] (2) White parallel light is irradiated onto the surface of the oxide film. The parallel light includes incident light A and incident light B.

[0010] (3) Part of the incident light is mirror-reflected on the surface of the oxide film, and part of the incident light is refracted through the oxide film. The refracted light is reflected back at the boundary of the stainless steel substrate to produce reflected light.

[0011] (4) The incident light A has the same optical path as the incident light B on the oxide film of 304 stainless steel. The incident light B and the incident light A have a certain distance between them. The distance causes the reflected light to interfere with the incident light B on the oxide film.

[0012] (5) Interference light forms interference fringes on the oxide film. After interference, which color of white parallel light is strengthened depends on the thickness of the oxide film. When white parallel light passes through an oxide film of a certain thickness, the vibration of a certain wavelength of light is strengthened, and the oxide film will show the color of the light corresponding to that wavelength.

[0013] The surface color of 304 stainless steel and its parts subjected to high-temperature oxidation treatment was tested using a spectrophotometer; the highest temperature experienced by the 304 stainless steel and its parts was obtained.

[0014] Step 5) is implemented in the following way:

[0015] The colorimetric properties of 304 stainless steel and its parts treated with high-temperature oxidation were measured using a spectrophotometer to obtain L* and a* values. The L* value decreased with increasing high-temperature oxidation time, and the higher the oxidation temperature, the lower the L* value. The a* value increased with increasing high-temperature oxidation time, and the higher the oxidation temperature, the higher the a* value.

[0016] The L* values ​​obtained are as follows: L* value of 304 stainless steel surface at 300℃ versus time, L* value of 304 stainless steel surface at 400℃ versus time, L* value of 304 stainless steel surface at 500℃ versus time, L* value of 304 stainless steel surface at 600℃ versus time, and L* value of 304 stainless steel surface at 700℃ versus time.

[0017] The obtained a* values ​​are, in order, the a* value of 304 stainless steel surface at 300℃ and time, the a* value of 304 stainless steel surface at 400℃ and time, the a* value of 304 stainless steel surface at 500℃ and time, the a* value of 304 stainless steel surface at 600℃ and time, and the a* value of 304 stainless steel surface at 700℃ and time.

[0018] Based on the L* and a* values, the relationships between temperature and L* and a* values, and the relationship between the highest temperature T and L* value, are derived. The mathematical expression of these relationships is as follows:

[0019] T = k1(L*)³ + k2(L*) 2 +k3L*+k4 ……(1)

[0020] 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 spectrophotometer; k1, k2, k3, and k4 are coefficients.

[0021] The relationship between the maximum temperature T and the a* value is mathematically expressed as follows:

[0022] T=j1(a*) 3 +j2(a*) 2 +j3(a*)+j4……(2)

[0023] 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 spectrophotometer; j1, j2, j3, and j4 are coefficients.

[0024] Substituting the L* value into equation (1) yields the highest temperature experienced by the 304 stainless steel and its components; substituting the a* value into equation (2) yields the highest temperature experienced by the 304 stainless steel and its components.

[0025] The advantages of this invention are:

[0026] 1. The method disclosed in this invention is to analyze the highest temperature experienced by the surface condition of 304 stainless steel and its parts that have undergone high temperature, without the need to do test preparation before experiencing high temperature.

[0027] 2. The method disclosed in this invention analyzes the highest temperature experienced by the surface condition of 304 stainless steel and its parts that have undergone high temperatures, without requiring observation during operation, and has a wide range of applications.

[0028] 3. The method disclosed in this invention is to analyze the highest temperature experienced by the surface condition of 304 stainless steel and its parts that have undergone high temperature. The analysis process is non-contact and does not damage the surface. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention or the existing design methods, the accompanying drawings required in the description of the embodiments or the existing design methods will be briefly introduced below:

[0030] Figure 1 This is a schematic diagram illustrating the principle of interference colors in oxide films;

[0031] Figure 2 This refers to the change in the L* value of the color during the high-temperature oxidation process of 304 stainless steel.

[0032] Figure 3 This refers to the change in the L* value of the color during the high-temperature oxidation process of 304 stainless steel.

[0033] Figure 4 This relates to the highest temperature T experienced by 304 stainless steel and its components, and the value of L*.

[0034] Figure 5 The a* value represents the color of 304 stainless steel after high-temperature oxidation, corresponding to the highest temperature it has experienced.

[0035] In the figure, 101, incident light A; 102, incident light B; 103, refracted light; 104, reflected light; 105, interference light; 106, incident normal; 107, oxide film; 108, stainless steel substrate; 201, L* value of 304 stainless steel surface changing with time at 300℃; 202, L* value of 304 stainless steel surface changing with time at 400℃; 203, L* value of 304 stainless steel surface changing with time at 500℃; 204, L* value of 304 stainless steel surface changing with time at 600℃; 205, L* value of 304 stainless steel surface changing with time at 700℃. Curves showing the variation of a* value of 304 stainless steel surface with time at 300℃ (301); 302, 400℃; 303, 500℃; 304, 600℃; 305, 700℃; 401, the curve showing the maximum heating temperature corresponding to the L* value of 304 stainless steel surface after high-temperature oxidation for a certain time; 501, the curve showing the maximum heating temperature corresponding to the a* value of 304 stainless steel surface after high-temperature oxidation for a certain time. Detailed Implementation

[0036] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, thereby providing a full understanding of how the present invention uses technical means to solve technical problems and achieve technical effects, and enabling its implementation. It should be noted that, as long as there is no conflict, the various embodiments and features in each embodiment of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0037] Furthermore, numerous specific details are set forth in the following description for purposes of explanation, in order to provide a thorough understanding of the embodiments of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without the specific details herein or the particular methods described.

[0038] like Figure 1As shown, this invention relates to a method for analyzing the highest temperature experienced by 304 stainless steel and its components, characterized in that: the oxide film on the surface of the 304 stainless steel is selected to be a colorless and transparent film, which can produce an interference effect of visible light; the principle of its light interference is as follows. Figure 1 As shown, when parallel white light irradiates the surface of oxide film 107, the parallel light includes incident light A101 and incident light B102. Part of incident light A101 undergoes specular reflection on the upper surface of oxide film 107, and part of it is refracted at the incident normal 106 via oxide film 107 to produce refracted light 103. Refracted light 103 is reflected back at the boundary of stainless steel substrate 108 to produce reflected light 104.

[0039] The incident light B102 follows the same optical path as the incident light A101 on the oxide film 107 of 304 stainless steel. There is a certain distance between the incident light B102 and the incident light A101. This distance causes the reflected light 104 to undergo specular reflection at the oxide film 107, forming interference light 105. The interference light 105 forms interference fringes on the oxide film 107. After interference, the color of the parallel white light depends on the thickness of the oxide film. When the parallel white light passes through an oxide film of a certain thickness, the vibration of a certain wavelength is strengthened, and the oxide film displays the color corresponding to that wavelength. A spectrophotometer was used to perform colorimetric tests on the surface of the 304 stainless steel and its components after high-temperature oxidation. Color changes are described in [reference needed]. Figure 2 and Figure 3 ,

[0040] The L* value decreases with increasing high-temperature oxidation time, then the rate of decrease slows down and stabilizes after a certain period of time. The higher the oxidation temperature, the lower the L* value.

[0041] The a* value increases with increasing high-temperature oxidation time, then the rate of increase slows down and stabilizes after a certain period of time. The higher the oxidation temperature, the higher the a* value.

[0042] Figure 2 In the figures, the L* values ​​are as follows: Curve 201 for the L* value of 304 stainless steel surface at 300℃ over time; Curve 202 for the L* value of 304 stainless steel surface at 400℃ over time; Curve 203 for the L* value of 304 stainless steel surface at 500℃ over time; Curve 204 for the L* value of 304 stainless steel surface at 600℃ over time; and Curve 205 for the L* value of 304 stainless steel surface at 700℃ over time. The lower the L* value, the higher the maximum temperature experienced by the 304 stainless steel and its components.

[0043] Figure 3In the diagram, the bottommost a* value is curve 301, showing the change of a* value of 304 stainless steel surface over time at 300℃. Moving upwards, the curves show: curve 302, curve 303, curve 304, curve 305, and curve 305, respectively. A higher a* value indicates a higher maximum temperature experienced by the 304 stainless steel and its components; a lower a* value indicates a lower maximum temperature experienced by the 304 stainless steel and its components.

[0044] The different high-temperature oxidation temperatures experienced by 304 stainless steel and its components result in varying oxide film thicknesses on their surfaces, leading to different interference colors. This, in turn, results in different L* and a* values ​​measured using a spectrophotometer. Based on this pattern, a method can be provided to analyze the highest temperature experienced during the high-temperature oxidation of 304 stainless steel and its components. The specific steps are as follows:

[0045] according to Figure 2 , Figure 3 The surface color L* and a* values ​​of stainless steel after high-temperature oxidation at different temperatures for a certain period of time were obtained. Based on the L* and a* values, the relationship between temperature and the L* and a* values ​​was derived. Figure 4 , Figure 5 As shown:

[0046] Figure 4 The curve in the middle is the maximum heating temperature curve corresponding to the L* value of the 304 stainless steel surface after high-temperature oxidation for a certain period of time. The lower the L* value, the higher the maximum temperature experienced by the 304 stainless steel and its parts.

[0047] Figure 5 The curve in the middle is the maximum heating temperature curve corresponding to the a* value of the 304 stainless steel surface after high-temperature oxidation for a certain period of time. The higher the a* value, the higher the maximum temperature experienced by the 304 stainless steel and its parts.

[0048] The specific steps are as follows:

[0049] Depend on Figure 4 The relationship between the highest temperature T experienced by 304 stainless steel and its components and the L* value can be summarized as follows:

[0050] T = k1(L*)³ + k2(L*) 2 +k3L*+k4 ……(1)

[0051] 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 spectrophotometer; k1, k2, k3, and k4 are coefficients.

[0052] Depend on Figure 5 The relationship between the highest temperature T experienced by 304 stainless steel and its components and the a* value can be summarized as follows:

[0053] T=j1(a*) 3 +j2(a*) 2 +j3(a*)+j4……(2)

[0054] 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 spectrophotometer; j1, j2, j3, and j4 are coefficients.

[0055] After the 304 stainless steel and its parts to be analyzed have undergone high-temperature oxidation in air for a certain period of time, the surface is subjected to colorimetric testing using a spectrophotometer, and the L* and a* values ​​measured by SCI are recorded.

[0056] Substituting the L* value into Equation 1 yields the highest temperature experienced by the 304 stainless steel and its components; substituting the a* value into Equation 2 yields the highest temperature experienced by the 304 stainless steel and its components.

[0057] Based on the above principles, two embodiments are given below to illustrate the analysis method of the present invention. Example 1

[0058] This embodiment discloses a method for analyzing the highest temperature experienced by 304 stainless steel and its components, the principle of which is as follows: Figure 4 In other words, the lower the L* value, the higher the maximum temperature that 304 stainless steel and its parts can withstand. The general rule is as follows:

[0059] T = k1(L*)³ + k2(L*) 2 +k3L*+k4 ……(1)

[0060] In the formula,

[0061] T represents the highest temperature experienced by 304 stainless steel and its components.

[0062] L* is the L* value of the surface of 304 stainless steel and its parts measured by a spectrophotometer.

[0063] k1, k2, k3, and k4 are coefficients;

[0064] For the 304 stainless steel and its components subjected to high-temperature oxidation in air for a certain period of time, the surface colorimetric value was measured using a spectrophotometer. Applying Equation 1, the highest temperature experienced by the 304 stainless steel and its components can be obtained as follows:

[0065] T = k1(L*)³ + k2(L*)2 +k3L*+k4.

[0066] The preferred values ​​for the coefficients in the formula are as follows:

[0067] k1 = -1.6585 × 10 -2 ;

[0068] k2 = 2.3855;

[0069] k3 = -117.6304;

[0070] k4 = 2619.8094. Example 2

[0071] This embodiment discloses a method for analyzing the highest temperature experienced by 304 stainless steel and its components. The principle and law are as follows: Figure 5 In other words, the higher the a* value, the higher the maximum temperature that 304 stainless steel and its parts can withstand. The general rule is as follows:

[0072] T=j1(a*) 3 +j2(a*) 2 +j3(a*)+j4……(2)

[0073] In the formula,

[0074] T represents the highest temperature experienced by 304 stainless steel and its components.

[0075] a* is the a* value of the surface of 304 stainless steel and its parts measured by a spectrophotometer;

[0076] j1, j2, j3, and j4 are coefficients;

[0077] For the 304 stainless steel and its components subjected to high-temperature oxidation in air for a certain period of time, the surface colorimetric value was measured using a spectrophotometer. Applying Equation 2, the highest temperature experienced by the 304 stainless steel and its components can be obtained as follows:

[0078] T = j1(a*) 3 +j2(a*) 2 +j3(a*)+j4.

[0079] The preferred values ​​for the coefficients in the formula are as follows:

[0080] j1 = 6.1406 × 10 -2 ;

[0081] j2 = -2.7541;

[0082] j3 = 55.0889;

[0083] j4=267.4303.

[0084] The principle of this invention is as follows: In an air atmosphere and high temperature environment, a very thin and dense oxide film will form on the surface of 304 stainless steel and its parts. The higher the temperature, the faster the oxidation rate and the thicker the oxide film. Under constant environmental conditions, when the oxide film thickness reaches a certain level, the metal elements cannot penetrate this thick oxide film, the oxidation reaction rate tends to stagnate, and the film layer no longer grows thicker. Therefore, after a certain period of oxidation, the thickness of the oxide film on the surface of 304 stainless steel and its parts is related to the temperature of the environment.

[0085] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention, as well as applications to fields not mentioned in the present invention, should 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: The process includes the following steps: (1) Selecting a colorless and transparent oxide film on the surface of 304 stainless steel, which can produce an interference effect of visible light; (2) Irradiating the oxide film (107) surface with parallel white light, the parallel light including incident light A (101) and incident light B (102); (3) Part of incident light A (101) undergoes specular reflection on the surface of the oxide film (107), and part of it is refracted (103) through the oxide film (107). The refracted light (103) is reflected back at the boundary between the stainless steel substrate (108) and the oxide film (104) to produce reflected light (104); (4) Incident light B (102) is irradiated on the surface of 304 stainless steel.

4. The stainless steel oxide film (107) has the same optical path as the incident light A (101). The incident light B (102) and the incident light A (101) are spaced apart. The space is formed by the reflected light (104) and the incident light B (102) forming interference light (105) on the oxide film (107); (5) The interference light (105) forms an interference fringe film on the oxide film (107). After interference, the color of the white parallel light is strengthened depending on the thickness of the oxide film. When the white parallel light passes through an oxide film of a certain thickness, the vibration of a certain wavelength of light is strengthened, and the oxide film presents the color of the light corresponding to that wavelength. The surface color of 304 stainless steel and its components subjected to high-temperature oxidation treatment was measured using a spectrophotometer; the highest temperature experienced by the 304 stainless steel and its components was obtained. Step 5) is implemented in the following way: The colorimetric properties of 304 stainless steel and its parts treated with high-temperature oxidation were measured using a spectrophotometer to obtain L* and a* values. The L* value decreased with increasing high-temperature oxidation time, and the higher the oxidation temperature, the lower the L* value. The a* value increased with increasing high-temperature oxidation time, and the higher the oxidation temperature, the higher the a* value. The L* values ​​obtained are as follows: L* value of 304 stainless steel surface at 300℃ versus time (201), L* value of 304 stainless steel surface at 400℃ versus time (202), L* value of 304 stainless steel surface at 500℃ versus time (203), L* value of 304 stainless steel surface at 600℃ versus time (204), and L* value of 304 stainless steel surface at 700℃ versus time (205). The obtained a* values ​​are as follows: a* value of 304 stainless steel surface at 300℃ versus time (301), a* value of 304 stainless steel surface at 400℃ versus time (302), a* value of 304 stainless steel surface at 500℃ versus time (303), a* value of 304 stainless steel surface at 600℃ versus time (304), and a* value of 304 stainless steel surface at 700℃ versus time (305). Based on the L* and a* values, the relationships between the maximum temperature and the L* and a* values, and the relationship between the maximum temperature T and the L* value, are derived. The mathematical expression of these relationships 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 spectrophotometer; k1, k2, k3, and k4 are coefficients. The relationship between the maximum temperature T and the a* value is mathematically expressed as follows: T=j1(a*) 3 +j2(a*) 2 +j3(a*)+j4……(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 spectrophotometer; j1, j2, j3, and j4 are coefficients. Substituting the L* value into equation (1) yields the highest temperature experienced by the 304 stainless steel and its components; substituting the a* value into equation (2) yields the highest temperature experienced by the 304 stainless steel and its components.

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