CN111850563A - Rapid detection method for surface structure of nickel-based superalloy forging and high-power structure corrosion liquid - Google Patents
Rapid detection method for surface structure of nickel-based superalloy forging and high-power structure corrosion liquid Download PDFInfo
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Abstract
The invention provides a rapid detection method for surface structure of a nickel-based superalloy forging and a high-power structure corrosive liquid, which comprises the following steps: performing macroscopic structure corrosion and inspection on the surface of the machined forging: if the surface structure is uniform, judging that the surface quality of the forging is qualified; if a suspected coarse crystal or bright-dark uneven structure part exists on the surface, performing high-power structure corrosion on the part and performing metallographic structure inspection by using an in-situ metallographic instrument: if the coarse grain structure is not found at the part or the grain size of the part does not exceed the product rating requirement, judging that the surface quality of the forging is qualified; otherwise, judging that the surface quality of the forging is unqualified. The invention can carry out high-power structure inspection on coarse grains and light and dark uneven structures on the premise of not damaging the integrity of the forge piece to obtain clear corrosion surfaces and grain structures, thereby achieving the purposes of comprehensively screening unqualified products and avoiding judging qualified forge pieces due to false coarse grains.
Description
Technical Field
The invention relates to the technical field of preparation of high-temperature alloy forgings, in particular to a rapid detection method for surface structures of nickel-based high-temperature alloy forgings and a high-power structure corrosive liquid.
Background
With the increase of thrust-weight ratio of the aircraft engine, the nickel-based high-temperature alloy which is difficult to deform, such as GH4720Li nickel-based high-temperature alloy, gradually becomes the first material of a high-performance turbine disk. The high service temperature and harsh service environment require that the disc forging has extremely uniform grain structure, and the strength, creep deformation and fatigue performance of service materials are seriously influenced by the coarse crystal or mixed crystal structure on the surface and inside of the disc forging. If abnormal grain structures are not detected in time in the production process of the disc forging, the safe use and the service life of the engine are seriously threatened.
Compared with other materials, particularly the nickel-based high-temperature alloy which is difficult to deform, the nickel-based high-temperature alloy for the aircraft engine is high in raw material cost, low in yield and extremely high in processing difficulty, and the disc forging piece is mainly applied to military and civil aircraft engines, so that the safety and the reliability of the disc forging piece are important. Therefore, how to reduce the material loss, improve the yield and ensure the safety and reliability of the disc forging becomes the key point of defect detection in the preparation process of the disc forging.
In the production process of the disc forging, defects such as inclusions, cracks, coarse crystals and the like in the disc forging are usually detected and judged by adopting water immersion ultrasonic flaw detection, but a dead zone of 3-5mm exists on the surface of the disc forging, so that the surface defect cannot be detected. The detection of the corrosion of the macrostructure on the surface of the disc forging is an important process for detecting the surface quality, the defect structure and the abnormal grains of the forging because of simplicity, practicability, low cost and complete detection. However, since the macroscopic structure corrosion inspection is performed by a visual inspection method, the abnormal grain structure is often missed due to the insufficient inspection. And is often judged as coarse grains by eyes, but the grain structure is actually a pseudo coarse grain phenomenon which meets the standard requirement.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a rapid detection method for the surface structure of a nickel-based superalloy forging and a high-power structure corrosion solution so as to alleviate at least one of the technical problems.
In order to achieve the above purpose of the present invention, the following technical solutions are adopted:
in a first aspect, the invention provides a method for rapidly detecting surface structure of a nickel-based superalloy forging, which comprises the following steps:
performing macroscopic structure corrosion and inspection on the surface of the machined forging:
if macroscopic coarse crystals and light and shade uneven structures are not found on the surface, judging that the surface structure of the forging is qualified;
if a part with suspected coarse crystals or uneven bright and dark tissues exists on the surface, performing high-power tissue corrosion and inspection on the part: if the coarse grain structure is not found at the part, or the grain size of the part does not exceed the product rating requirement (technical document requirement), judging that the surface structure of the forging is qualified; otherwise, judging that the surface structure of the forging is unqualified;
wherein, the high-power tissue corrosive liquid used for the high-power tissue corrosion can dissolve impurity elements in the alloy, and the clear grain boundary morphology is displayed under a metallographic microscope.
Further, the high power tissue etching solution used for high power tissue etching comprises CuCl2HCl and absolute ethanol;
preferably, CuCl2The ratio of HCl to absolute ethyl alcohol is CuCl2: HCl: absolute ethanol 3 g: (15-25) mL: (25-35) mL, preferably 3 g: 20mL of: 30 mL;
preferably, the mass concentration of HCl is 36-38%.
Further, the corrosion time of the high-power tissue corrosion is 20 to 40s, preferably 35 s.
In a second aspect, the present invention provides a high power tissue etching solution for achieving high power tissue etching in the method of the first aspect, comprising CuCl2HCl and absolute ethanol.
Further, CuCl2The ratio of HCl to absolute ethyl alcohol is CuCl2: HCl: absolute ethanol 3 g: (15-25) mL: (25-35) mL, preferably 3 g: 20mL of: 30 mL;
preferably, the mass concentration of HCl is 36-38%.
The invention has the following beneficial effects:
the method of the invention carries out high-power tissue corrosion and inspection on the suspected coarse grain or bright and dark uneven tissue after low-power tissue corrosion and inspection, can carry out high-power tissue inspection on the coarse grain and bright and dark uneven tissue on the premise of not cutting a test piece and ensuring the integrity of the forged piece, obtains clear corrosion surface and grain size tissue, achieves the purposes of comprehensively screening unqualified products and avoiding judging qualified forged pieces due to false coarse grains, improves the inspection accuracy, reduces the material loss, ensures the safety and reliability of the forged piece, has short process flow, and is easy to realize in batch production.
The high-power tissue corrosion solution provided by the invention has uniform corrosion effect, a corrosion surface is clear and visible, the removal amount is small in the local polishing process of high-power tissue inspection, and the defect characteristics are basically reserved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a photograph of a macrostructured corrosion surface of a GH4720Li nickel-base superalloy disk forging provided in example 1 of the present invention;
FIG. 2 is a photograph of a macrostructured corrosion surface of a GH4720Li nickel-base superalloy disk forging provided in example 2 of the present invention;
FIG. 3 is a photograph of high microstructure corrosion of a GH4720Li nickel-base superalloy disc forging provided in example 2 of the present invention;
FIG. 4 is a photograph of high microstructure corrosion of a GH4720Li nickel-base superalloy disk forging provided in example 3 of the present invention;
FIG. 5 is a photograph of high microstructure corrosion of a GH4720Li nickel-base superalloy disk forging provided in example 6 of the present invention;
FIG. 6 is a photograph of high microstructure corrosion of a GH4710 nickel-base superalloy disc forging provided in example 7 of the present invention;
FIG. 7 is a photograph of high microstructure corrosion of a GH4730 nickel-base superalloy disc forging provided in example 8 of the present invention;
FIG. 8 is a photograph of high microstructure corrosion of a GH4720Li nickel-base superalloy disk forging according to a comparative example of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The macroscopic structure corrosion process in the prior art often has the phenomenon of missing coarse grains or pseudo coarse grains. This phenomenon is caused by the high degree of high-temperature alloying of the nickel base of GH4720Li, the tendency of composition segregation to occur and the appearance of uneven bright and dark structure after corrosion of the macrostructure. The pseudo-macrocrystalline phenomenon is usually found by high power tissue examination after cutting a high power sample. However, the integrity of the forge piece is damaged in the mode, and the subsequent preparation process cannot be carried out.
For suspected coarse grains and light and shade uneven structures, high-power structure corrosion is carried out on the basis of low-power structure corrosion, and a sample does not need to be cut, so that the purpose of accurately and efficiently screening unqualified products is achieved on the basis of the integrity of the forge piece.
According to one aspect of the invention, a method for rapidly detecting the surface structure of a nickel-based superalloy forging is provided, which comprises the following steps:
performing macroscopic structure corrosion and inspection on the surface of the machined forging:
if macroscopic coarse crystals and light and shade uneven structures are not found on the surface, judging that the surface structure of the forging is qualified;
if a part with suspected coarse crystals or uneven bright and dark tissues exists on the surface, performing high-power tissue corrosion and inspection on the part: the high-power tissue corrosion solution used for high-power tissue corrosion can dissolve impurity elements in the alloy, and the clear grain boundary morphology is displayed under a metallographic microscope. Under a metallographic microscope or an in-situ metallographic microscope, clear grain structures, microstructures with equal precipitation and distribution states of the microstructures can be observed.
If the coarse grain structure is not found at the part, or the grain size of the part does not exceed the product rating requirement, judging that the surface structure of the forging is qualified;
otherwise, judging that the surface structure of the forging is unqualified.
"Nickel-base superalloys" include, but are not limited to, GH4720Li nickel-base superalloys; "Nickel base superalloy forgings" include, but are not limited to, GH4720Li nickel base superalloy disk forgings.
"macroscopic corrosion" and "macroscopic corrosion" are relative meanings.
Macrostructure corrosion is a process of obtaining a macroscopic structure appearance by using macrostructure corrosion liquid corrosion, and shrinkage porosity, segregation and various macroscopic defects capable of being exposed under macroscopical conditions can be corroded.
The high-power tissue corrosion is a process of obtaining microstructure morphology by utilizing high-power tissue corrosion liquid corrosion, and microstructures with equal grain size and precipitation can be observed by utilizing a metallographic microscope.
"macroscopic tissue examination" is a part of a tissue examination, with macroscopic versus macroscopic.
Macrostructural examination, also called macroscopic examination, is a method for examining macroscopic defects and tissue inhomogeneity of a material by naked eyes or under a magnifying glass of which the magnification is not more than ten times.
The high power tissue inspection, namely microscopic tissue inspection, is an inspection method for observing and analyzing the interior of a metal material by using a microscope with magnification of 100-2000 times. The present invention relates generally to the examination of grain size distribution in superalloys.
The "part suspected of coarse grains or uneven bright and dark structure" means that the high-temperature alloying degree of GH4720Li nickel base is high, so that the composition segregation is easy to occur and the macroscopic structure is corroded and then shows uneven bright and dark structure.
The method can obtain clear corrosion surface and grain size organization by performing high-power organization corrosion and inspection on the suspected coarse grain or the light and shade uneven organization, achieves the purposes of comprehensively screening unqualified products and avoiding the occurrence of false coarse grain phenomenon, and improves the inspection accuracy. The method does not damage the integrity of the forge piece, can continue the subsequent preparation process, has short process flow and is easy to realize in batch production.
The invention utilizes in-situ metallographic examination to inspect the high power structure on the premise of not cutting the high power sample, and can overcome the problem of uncertain detection of the forging structure in the current production flow.
In some preferred embodiments, the high power tissue etching solution used for high power tissue etching comprises CuCl2HCl and absolute ethanol.
Preferably, CuCl2The addition ratio of HCl to absolute ethyl alcohol is CuCl2: HCl: absolute ethanol 3 g: (15-25) mL: (25-35) mL, more preferably 3 g: 20mL of: 30 mL.
CuCl2Typical but not limiting examples of the amount of (b) are 3 g; typical but non-limiting examples of HCl added are 15, 16, 18, 20, 22, 24 or 25 mL; the amount of absolute ethanol added is typically, but not limited to, 25, 26, 28, 30, 32, 34, or 35mL, for example.
Preferably, the mass concentration of HCl is 36-38%, for example 36%, 37% or 38%.
The adopted high power tissue corrosive liquid passes through CuCl2The HCl and the absolute ethyl alcohol are matched with each other, so that impurity elements in the alloy can be dissolved, and the clear grain boundary morphology is displayed under a metallographic microscope. Under a metallographic microscope or an in-situ metallographic microscope, clear grain structures, microstructures with equal precipitation and distribution states of the microstructures can be observed.
In some preferred embodiments, the high-power tissue corrosion liquid is brushed, so that the forge piece does not need to be completely immersed in the corrosion liquid, and waste and pollution are avoided.
When the high-power tissue corrosive liquid is used for corroding the local part of the forging, the forging is placed in a corrosion groove of a fume hood, and the outer surface of the forging is uniformly brushed by using a brush. The high-power tissue corrosion has a corrosion time of 20 to 40s, for example, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39s, preferably 35 s.
The corrosion time is too short, the grain boundary corrosion effect is not obvious in brightness or can not be displayed, and the metallographic structure is difficult to distinguish; the crystal boundary is corroded by the long corrosion time, and the grain structure is difficult to distinguish.
In some preferred embodiments, the macrostructural etching solution used for macrostructural etching includes copper sulfate pentahydrate, concentrated H2SO4And HCl.
Preferably, CuSO4·5H2O, concentrated H2SO4And HCl is added in a ratio of CuSO4·5H2O: concentrated H2SO4: HCl 50g: (10-15) mL: (160-180) mL, preferably 50g:12mL of: 170 mL.
CuSO4·5H2The amount of O added is typically, but not limited to, for example, 50 g; concentrated H2SO4Is typically, but not limited to, for example, 10, 11, 12, 13, 14, or 15 mL; typical but non-limiting amounts of HCl added are, for example, 160, 162, 165, 170, 173, 175, or 178 mL.
Preferably, the concentrated H2SO4Is 95-98%, for example 95%, 96%, 97% or 98%, and the mass concentration of HCl is 36-38%, for example 36%, 37% or 38%.
The macroscopic texture corrosion liquid adopting the formula can be used for observing the uniformity of the surface texture of the forge piece and the distribution of coarse crystal and mixed crystal textures by naked eyes or under a magnifying glass of which the magnification is not more than ten times.
In some preferred embodiments, the macrostructure corrosion solution is used for treating the surface of the forging piece in a brush coating mode, so that waste and pollution are avoided.
When the macrostructure corrosion liquid is used for carrying out corrosion treatment on the forged piece, the forged piece is placed in a corrosion groove of a fume hood, the outer surface of the forged piece is uniformly brushed by using a brush, and the corrosion condition is detected in the corrosion process. The corrosion time is prolonged or shortened according to the change of the surface state, and the corrosion time of the macrostructure corrosion is 30-60min, such as 31, 35, 38, 40, 45, 46, 48, 50, 55, 58min, preferably 45 min.
In some preferred embodiments, the method for preparing the macrostructural etching solution comprises: adding copper sulfate pentahydrate and concentrated H2SO4And sequentially adding HCl, and uniformly mixing for later use.
In some embodiments, the components in the preparation of the macrostructure corrosion solution are sequentially added into copper sulfate pentahydrate, concentrated sulfuric acid and hydrochloric acid, and are uniformly stirred to obtain the macrostructure corrosion solution.
Adding copper sulfate into concentrated sulfuric acid, stirring thoroughly, dissolving copper sulfate completely with concentrated sulfuric acid, and adding hydrochloric acid. If hydrochloric acid is added to the copper sulfate first, the copper sulfate is not sufficiently dissolved.
In some preferred embodiments, the forging to be detected is obtained by heat treatment, water immersion ultrasonic flaw detection and machining, and the machined forging meets the following requirements: the roughness Ra of the surface of the forging is less than or equal to 3.2 μm, for example, 3.0, 2.5, 2.0, 1.5 or 1.0 μm, preferably 1.6 μm.
The purpose of heat treatment is to adjust the structure and mechanical property of the material and ensure that the forged piece has good use conditions. The purpose of water immersion ultrasonic flaw detection is to screen forgings with defects such as inclusions, slag inclusions, cracks and the like. The machining after flaw detection aims at removing a flaw detection layer and ensuring the roughness of the disc before corrosion of the macrostructure, and the macrostructure corrosion liquid can be directly coated on the surface for corrosion.
In some preferred embodiments, the method further comprises: firstly, grinding and polishing the surface of the machined forging, and then, carrying out macroscopic structure corrosion.
Preferably, the method further comprises: after macroscopic structure corrosion, carrying out first cleaning and drying on a corrosion surface, and then carrying out inspection;
preferably, the first cleaning comprises sequentially cleaning with persulfate solution, clean water and absolute ethanol;
persulfates include, but are not limited to, ammonium persulfate.
After completing the corrosion of the macrostructure of the forge piece, cleaning the corrosion surface of the forge piece by adopting a persulfate solution, then cleaning by using clear water, and finally cleaning by using absolute ethyl alcohol; and then drying: and (4) placing the forged piece cleaned by the absolute ethyl alcohol in a fume hood, and drying the forged piece by using a fan.
The purpose of persulfate cleaning is to remove corrosion products from the surface after corrosion.
Preferably, the persulfate solution has a concentration of 5-30% by mass, for example 5, 6, 7, 8, 10, 15, 20, 25, 28 or 29%, preferably 10%.
And (4) placing the corroded forged piece in a place with sufficient illumination, carrying out surface texture corrosion inspection, photographing and recording, and entering the next process if no coarse crystal is displayed.
In some preferred embodiments, the method further comprises: and grinding and polishing the part, and then carrying out high-power tissue corrosion.
Sanding is performed by using sand paper, and polishing is performed by using diamond polishing solution.
Preferably, the method further comprises: after high-power tissue corrosion, carrying out second cleaning and drying on the corrosion surface, and then carrying out inspection;
preferably, the second cleaning comprises sequentially cleaning with clear water and absolute ethanol.
After the high power tissue is corroded, cleaning the corroded surface with clear water and absolute ethyl alcohol, drying the forged piece if a fan is used for blowing the forged piece, then carrying out high power tissue inspection on suspected coarse grains or uneven parts, and grading the grain size.
In some preferred embodiments, the high power tissue examination is performed using a handheld metallographic microscope.
Suspected coarse grains or uneven crystal grains which are generated on the surface in the high-power tissue corrosion process and are difficult to judge are inspected by a handheld metallographic microscope, and the site meticulous and accurate judgment can be carried out.
The inspection times of the handheld microscope are 50 times (overall appearance), 100 times (grain size), 200 times (auxiliary inspection grain) and 500 times (microcosmic phase and precipitated phase), the microscope can adjust the inspection part at any time, and the software can be installed on electronic equipment such as a computer, a tablet personal computer or a mobile phone.
In a specific embodiment, the rapid detection of the surface structure of the GH4720Li nickel-base superalloy disc forging provided by the invention is performed after the disc forging is subjected to heat treatment, water immersion ultrasonic flaw detection and machining. The method comprises the following specific steps:
1) after carrying out standard solid solution and aging heat treatment on the metallographic phase of the disc forging, judging that metallurgical defects influencing the service performance of the material do not exist inside the disc forging through water immersion ultrasonic flaw detection;
preferably, in step 1), the surface has a roughness Ra of 3.2 μm or less, preferably 1.6 μm.
2) For the disk forging subjected to water immersion and ultrasonic flaw detection, after a surface flaw detection layer is machined, firstly, clean water and then absolute ethyl alcohol are used for cleaning oil stains on the surface, and then, the cleaned disk forging is placed in a fume hood and is dried by a fan.
3) And (3) grinding the surface of the machined disc forging by using sand paper, and then polishing and cleaning the surface: firstly, cleaning oil stains on the surface of the disc forging piece with clean water and then absolute ethyl alcohol, then placing the cleaned disc forging piece in a fume hood, and drying the disc forging piece by using a fan.
4) Carrying out macroscopic structure corrosion on the outer surface of the disc forging: the disc forging piece is erected in a corrosion groove of a fume hood, the outer surface of the disc forging piece is uniformly brushed by using a brush to carry out macroscopic structure corrosion, and the corrosion condition is inspected in an intentional manner in the corrosion process;
as a preferred scheme, in the step 4), the macrostructure corrosion solution is prepared in advance, and the specific components are as follows: CuSO4·5H2O + concentrated H2SO4+ HCl. The preferable formula of the macrostructure corrosion solution is as follows: CuSO4·5H2O: concentrated H2SO4HCl 50g, 12mL, 170 mL. Concentrated H2SO4The mass concentration of (A) is 95-98%, and the mass concentration of HCl is 36-38%. The etching time is 30-60min, preferably 45 min.
5) Cleaning corrosion products: placing the disc forging into a water tank after the disc forging is corroded, and using ammonium persulfate (NH)4)2S2O8Cleaning the corrosion surface of the disc forging by using a solution, then cleaning by using clear water, and finally cleaning by using absolute ethyl alcohol;
preferably, (NH) in step 5)4)2S2O8The mass concentration of the solution is 5-30%, preferably 10%.
6) And (4) placing the disc forging cleaned by the absolute ethyl alcohol in a fume hood, and drying the disc forging by using a fan.
7) And (4) the corroded disc forging is placed at a place with sufficient illumination, the corrosion condition of the surface structure is checked, and the picture is taken for recording.
8) And if the macroscopic structure on the surface of the disc forging piece is corroded uniformly, and no obvious coarse crystal and light and shade nonuniform structure exists, judging that the disc forging piece is qualified.
9) If a part which is difficult to judge coarse crystals or has uneven tissues exists, polishing and high-power tissue corrosion are carried out on the part again, and after the corrosion surface is cleaned by clean water and absolute ethyl alcohol, the disc forging is dried by a fan;
preferably, in the step 9), after the local polishing is performed by using sand paper and diamond polishing solution, the local polishing is dried by using a fan. CuCl is adopted as high power tissue corrosive liquid2+ HCl + absolute ethanol. Preferably CuCl2: HCl: absolute ethanol 3 g: 20mL of: 30 mL. The HCl mass concentration is also 36-38%.
The etching time is 20-40s, and the preferable time is 35 s.
10) And (3) carrying out high-power tissue inspection on the suspected coarse-grained or bright-dark uneven tissue by adopting a handheld metallographic microscope, and grading the grain size.
11) If the coarse grain structure is not found, or the grain size of the pseudo coarse grain part does not exceed the product rating requirement, the disc forging is qualified.
Enough ventilation and lighting equipment is needed in the corrosion workshop, and a flushing facility is needed in the corrosion site so that the corrosion liquid can be flushed in time when splashed to the body of an operator; before and after corrosion, the packaging must be complete so as to prevent collision, scratch and pollution on the inspection surface in the transportation process.
In a second aspect, the invention provides a high power tissue etching solution for achieving high power tissue etching in the above method, comprising CuCl2HCl and absolute ethanol.
Preferably, CuCl2The ratio of HCl to absolute ethyl alcohol is CuCl2: HCl: absolute ethanol 3 g: (15-25) mL: (25-35) mL, preferably 3 g: 20mL of: 30 mL;
preferably, the mass concentration of HCl is 36-38%.
It should be noted that the meanings of the above components are the same as the meanings of the corresponding terms in the first aspect, and are not repeated herein.
The high-power tissue corrosive liquid provided by the invention can dissolve impurity elements in the alloy, and the clear grain boundary morphology is displayed under a metallographic microscope. Under a metallographic microscope or an in-situ metallographic microscope, clear grain structures, microstructures with equal precipitation and distribution states of the microstructures can be observed. The corrosion effect is uniform, the corrosion surface is clear and visible, the removal amount is small in the local polishing process of high-power tissue inspection, and the defect characteristics are basically reserved.
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Example 1
A method for rapidly detecting the surface structure of a GH4720Li nickel-based superalloy disc forging comprises the following steps:
the method comprises the steps of subjecting a disc forging to standard solid solution and aging heat treatment, judging that no metallurgical defect influencing the service performance of a material exists in the disc forging through ultrasonic flaw detection, machining a surface flaw detection layer, cleaning oil stains on the surface of the disc forging by using clean water and absolute ethyl alcohol, placing the disc forging in a fume hood, and drying the disc forging by using a fan. And then carrying out macroscopic structure corrosion on the outer surface of the disc forging.
Wherein the macrostructure corrosion inspection is directed to the inspection of the entire outer surface of the disc forging.
The specific steps of the macroscopic tissue corrosion inspection are as follows:
(1) macroscopic corrosion of tissue
The disc forging piece is erected in a corrosion groove of a fume hood, the outer surface of the disc forging piece is uniformly brushed by a brush for macroscopic structure corrosion, the corrosion time is 40min, and the formula of a corrosion solution is CuSO4·5H2O: concentrated H2SO4: 50g of HCl, 12mL of HCl and 170mL of HCl, and the corrosion condition is inspected by attention in the corrosion process;
(2) cleaning of
Cleaning the corrosion surface of the disc forging by using an ammonium persulfate solution (the mass concentration is 5-30%), then cleaning by using clear water, and finally cleaning by using absolute ethyl alcohol;
(3) drying
And (4) placing the disc forging cleaned by the absolute ethyl alcohol in a fume hood, and drying the disc forging by using a fan.
(4) Checking and shooting
And (3) placing the corroded disc forging at a place with sufficient illumination, carrying out surface texture corrosion inspection, and taking a picture for recording, as shown in figure 1.
The structure corrosion and the inspection are carried out according to the method, the surface corrosion is uniform after the inspection, coarse grains and a bright and dark uneven structure are not displayed, so that the high-power structure inspection is not required to be carried out continuously, and the product is qualified.
In this example, the concentration H is set to be high2SO4The mass concentration of (2) was 98% and the mass concentration of HCl was 37%.
Example 2
A method for rapidly detecting the surface structure of a GH4720Li nickel-based superalloy disc forging is different from that of embodiment 1 in that when a macroscopic structure is inspected in the step (4), the surface structure is observed to be uneven, a suspected coarse-grain structure part is inspected as shown in figure 2, and the disc forging cannot be judged to be a qualified product in the step, so that the high-magnification structure inspection is carried out.
The specific steps of the high power tissue examination are as follows:
(1) polishing treatment
And (3) after the macroscopic structure is corroded, the area which cannot be judged to be coarse grains or uneven structure is polished by using sand paper and diamond polishing solution, and then the area is dried by using a fan.
(2) High power tissue corrosion
Placing the disc forging in a corrosion groove of a fume hood, coating a corrosion solution on a local polishing area, wherein the corrosion time is 35s, and the formula of the corrosion solution is CuCl2: HCl: absolute ethanol 3 g: 20mL of: 30 mL.
(3) Cleaning and drying
And (4) after the corrosion surface is cleaned by clear water and absolute ethyl alcohol, drying the disc forging by using a fan.
(4) High power tissue examination
And (3) performing high-power tissue examination on the non-uniform tissue part by using a handheld metallographic microscope, and observing the obvious grain distribution and grain size of the part, grading the grain size, and photographing and recording the grain size as shown in figure 3.
The high power structure corrosion and the inspection are carried out according to the method, after the inspection, the average grain size of the part can reach ASTM 8 grade, the grain size acceptance requirement of the GH4720Li nickel-based superalloy disc forging is met, and the product is qualified as the pseudo coarse grains detected by the low power structure corrosion inspection.
In the present example, the HCl mass concentration was 37%.
Example 3
The method for rapidly detecting the surface structure of the GH4720Li nickel-based superalloy disc forging is different from that of the embodiment 2 in that the disc forging is judged to be unqualified by high-power structure inspection in the step (4), and the coarse-grain structure is shown in figure 4.
Fig. 4 shows that an obvious coarse-grained structure exists at the part, the average grain size does not reach the requirement of ASTM 8 grade, the grain size grade difference is greater than 2 grade, the grain size acceptance requirement of GH4720Li nickel-based superalloy disc forgings is not met, and the bright and dark uneven structure detected by macroscopic structure corrosion is proved to be the coarse-grained structure, so that the product is unqualified.
Example 4
This example differs from example 2 in that the etchant used in step (2) is CuCl2: HCl: absolute ethanol 3 g: 15mL of: 35 mL.
Example 5
This example differs from example 2 in that the etchant used in step (2) is CuCl2: HCl: absolute ethanol 3 g: 25mL of: 25 mL.
Example 6
This example differs from example 2 in that the etchant used in step (2) is CuCl2: HCl: distilled water 3 g: 20 ml: 30 ml.
The microstructure was etched in the etching solution in a high magnification manner, and the photograph of the microstructure was shown in FIG. 5. It can be observed that partial grain boundary corrosion is not obvious, and obvious watermark exists, so that the observation effect and the grain size rating are influenced.
Example 7
A rapid detection method for a high-power structure of the surface of a GH4710 nickel-based superalloy disc forging comprises the following steps: the disc forging was subjected to standard solid solution + aging heat treatment, and the surface texture was examined for high magnification after low magnification texture examination as in example 2.
The specific steps of the high power tissue examination are as follows:
(1) polishing treatment
And (3) polishing the surface area of the disc forging needing high-power tissue inspection by using sand paper and diamond polishing solution, and drying by using a fan.
(2) High power tissue corrosion
Placing the disc forging in a corrosion groove of a fume hood, coating a corrosion solution on a polishing area, wherein the corrosion time is 35s, and the formula of the corrosion solution is CuCl2: HCl: absolute ethanol 3 g: 20mL of: 30 mL.
(3) Cleaning and drying
And (4) after the corrosion surface is cleaned by clear water and absolute ethyl alcohol, drying the disc forging by using a fan.
(4) High power tissue examination
And (3) performing high-power tissue examination on the non-uniform tissue part by using a handheld metallographic microscope, and observing the obvious grain distribution and grain size of the part as shown in FIG. 6, grading the grain size, and photographing and recording.
In the present example, the HCl mass concentration was 37%.
Example 8
A rapid detection method for a high-power structure of the surface of a GH4730 nickel-based superalloy disc forging comprises the following steps: the disc forging was subjected to standard solid solution + aging heat treatment, and the surface texture was examined for high magnification after low magnification texture examination as in example 2.
The specific steps of the high power tissue examination are as follows:
(1) polishing treatment
And (3) polishing the surface area of the disc forging needing high-power tissue inspection by using sand paper and diamond polishing solution, and drying by using a fan.
(2) High power tissue corrosion
Placing the disc forging in a corrosion groove of a fume hood, coating a corrosion solution on a polishing area, wherein the corrosion time is 35s, and the formula of the corrosion solution is CuCl2: HCl: absolute ethanol 3 g: 20mL of: 30 mL.
(3) Cleaning and drying
And (4) after the corrosion surface is cleaned by clear water and absolute ethyl alcohol, drying the disc forging by using a fan.
(4) High power tissue examination
And (3) performing high-power tissue examination on the non-uniform tissue part by using a handheld metallographic microscope, and observing the obvious grain distribution and grain size of the part as shown in FIG. 7, grading the grain size, and photographing and recording.
In the present example, the HCl mass concentration was 37%.
Comparative example
A method for detecting the surface structure of a GH4720Li nickel-based superalloy disc forging only performs macroscopic structure corrosion inspection. The coarse grains were judged by visual inspection.
However, the phenomenon of pseudo-coarse grains was observed after cutting out a sample and performing a high magnification tissue examination. The specific checking steps are as follows:
cutting sample of macroscopic tissue corrosion (1)
The sample was sampled by wire cutting, and the portion to be observed was placed at the center of the test piece, and a test piece of 20mm in length × width × thickness × 20mm × 10mm was taken.
(2) Polishing treatment
And (3) polishing the cut sample by using sand paper and diamond polishing solution, and drying by using a fan.
(3) High power tissue corrosion
Smearing corrosive liquid on a local polishing area, wherein the corrosion time is 35s, and the formula of the corrosive liquid is CuCl2: HCl: absolute ethanol 3 g: 20mL of: 30 mL.
(4) Cleaning and drying
And (4) after the corroded surface is cleaned by clear water and absolute ethyl alcohol, drying the sample by using a fan.
(5) High power tissue examination
The sample is subjected to high power tissue examination by using a computer type metallographic microscope, the grain size is graded, and the picture is recorded as shown in fig. 8. The average grain size of the part can reach ASTM 8 grade, the grain size acceptance requirement of GH4720Li nickel-based superalloy disc forgings is met, pseudo coarse grains are proved to be detected by macroscopic structure corrosion, and therefore the product is qualified.
The surface of the disc forging is cut and sampled in the inspection process, the integrity of the disc forging is damaged, the size is changed, the requirement of the technical requirement on the size of the disc forging is not met, and therefore the disc forging can only be scrapped.
Compared with the prior art, the method has the advantages that a low-magnification tissue detection mode and a high-magnification tissue detection mode which do not damage the size and the integrity of the disc forging are adopted in the production process, the water immersion ultrasonic flaw detection process is matched, the blind area defects on the surface of the forging are accurately and quickly judged, and the condition that the qualified products are judged wrongly due to the pseudo-coarse-grain tissues can be effectively reduced.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for rapidly detecting the surface structure of a nickel-based superalloy forging is characterized by comprising the following steps:
performing macroscopic structure corrosion and inspection on the surface of the machined forging:
if macroscopic coarse crystals and light and shade uneven structures are not found on the surface, judging that the surface structure of the forging is qualified;
if a part with suspected coarse crystals or uneven bright and dark tissues exists on the surface, performing high-power tissue corrosion and inspection on the part: if the coarse grain structure is not found at the part or the grain size of the part does not exceed the product rating requirement, judging that the forging is qualified; otherwise, judging that the surface structure of the forging is unqualified;
wherein, the high-power tissue corrosive liquid used for the high-power tissue corrosion can dissolve impurity elements in the alloy, and the clear grain boundary morphology is displayed under a metallographic microscope.
2. The method of claim 1, wherein the high power tissue etching solution used for high power tissue etching comprises CuCl2HCl and absolute ethanol;
preferably, CuCl2The ratio of HCl to absolute ethyl alcohol is CuCl2: HCl: absolute ethanol 3 g: (15-25) mL: (25-35) mL, preferably 3 g: 20mL of: 30 mL;
preferably, the mass concentration of HCl is 36-38%.
3. Method according to claim 2, characterized in that the erosion time for high power tissue erosion is 20-40s, preferably 35 s.
4. A method according to any one of claims 1 to 3, wherein the macrostructural etching solution used for macrostructural etching comprises copper sulfate pentahydrate, concentrated H2SO4And HCl;
preferably, copper sulfate pentahydrate, concentrated H2SO4And HCl in a ratio of copper sulfate pentahydrate: concentrated H2SO4: HCl 50g: (10-15) mL: (160-180) mL, preferably 50g:12mL of: 170 mL;
preferably, the concentrated H2SO4The mass concentration of the HCl is 95-98 percent, and the mass concentration of the HCl is 36-38 percent;
preferably, the preparation method of the macrostructure corrosion solution comprises the following steps: HCl, copper sulfate pentahydrate and concentrated H2SO4Sequentially adding the components, and uniformly mixing for later use;
preferably, the corrosion time of the macrostructure corrosion is 30-60min, preferably 45 min.
5. A method according to any of claims 1 to 3, characterized in that the roughness Ra of the surface of the worked forging is 3.2 μm or less, preferably 1.6 μm;
preferably, the forged piece to be detected is subjected to heat treatment, water immersion ultrasonic flaw detection and machining to obtain a machined forged piece.
6. The method according to any one of claims 1-3, further comprising: firstly, grinding and polishing the surface of the machined forging, and then, carrying out macroscopic structure corrosion;
preferably, the method further comprises: after macroscopic structure corrosion, carrying out first cleaning and drying on a corrosion surface, and then carrying out inspection;
preferably, the first cleaning comprises sequentially cleaning with persulfate solution, clean water and absolute ethanol;
preferably, the persulfate solution has a concentration of 5 to 30% by mass, preferably 10% by mass.
7. The method according to any one of claims 1-3, further comprising: grinding and polishing the part, and then carrying out high-power tissue corrosion;
preferably, the method further comprises: after high-power tissue corrosion, carrying out second cleaning and drying on the corrosion surface, and then carrying out inspection;
preferably, the second cleaning comprises sequentially cleaning with clear water and absolute ethanol.
8. The method according to any one of claims 1 to 3, wherein the macroscopic tissue etching solution and the macroscopic tissue etching solution are independently etched by brushing;
preferably, the high-power tissue inspection is performed by using a handheld metallographic microscope, and the inspection times of the handheld metallographic microscope are 50 times, 100 times, 200 times and 500 times.
9. A high power tissue etching solution for achieving high power tissue etching in the method of any one of claims 1 to 8 comprising CuCl2HCl and absolute ethanol.
10. The high power tissue etching solution of claim 9, wherein the CuCl is2The ratio of HCl to absolute ethyl alcohol is CuCl2: HCl: absolute ethanol 3 g: (15-25) mL: (25-35) mL, preferably 3 g: 20mL of: 30 mL;
preferably, the mass concentration of HCl is 36-38%.
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