This standard specifies the guiding method for liquid penetrant testing of forged steel parts. This standard applies to liquid penetrant testing of materials. It can be effectively used for process inspection, final inspection and maintenance inspection of workpieces made of non-porous metals (including ferrous and non-ferrous metals), ceramics, plastics, glass and other materials. This method can be used to display surface open defects such as cracks, seams, heavy skin, delamination, through leakage and incomplete penetration. JB/T 8466-1996 Liquid penetrant testing method for forged steel parts JB/T8466-1996 Standard download decompression password: www.bzxz.net

JB/T 8466--96
This standard adopts ASTME165--80 "Standard for Liquid Penetrant Test Methods" in a non-equivalent manner. The main differences between this standard and ASTME165--80 are:
1. ASTMF165-80 consists of eight chapters including scope, applicable documents, method overview, definition, method classification and material types, operating methods, special requirements, identification and re-identification, as well as appendices A1, A2, and A3. This standard consists of six chapters including scope, method overview and classification, material types and test methods, operating methods, special requirements, identification and re-identification, and appendix A. 2. ASTME165-80 has four figures, and the remaining three figures are all decomposed parts of the first figure. This standard has only one figure. This standard is a guiding method standard. After selecting the type of liquid penetrant method, a special operating procedure should be prepared. The evaluation and acceptance conditions of defects should be agreed upon in advance by both the supply and demand parties.
Appendix A of this standard is the appendix of the standard.
This standard is proposed and managed by the Deyang Large Casting and Forging Research Institute of the Ministry of Machinery Industry. The main drafting unit of this standard is China Second Heavy Machinery Group Corporation. The main drafter of this standard is Jiang Liangsheng.
Mechanical Industry Standard of the People's Republic of China
Liquid Penetrant Inspection Method for Forged Steel Parts
JB/T8466--96
This standard specifies the guiding method for surface penetration inspection of forged steel parts. This standard is applicable to liquid penetrant inspection of materials. It can be effectively used for process inspection, final inspection and maintenance inspection of workpieces made of non-porous metals (including ferrous and non-ferrous metals), ceramics, plastics, glass and other materials. This method can be used to display surface open defects such as cracks, seams, heavy skin, cold shut, delamination, through leakage and incomplete penetration. 2 Method Overview and Classification
2.1 Liquid penetrant inspection is a method for detecting surface open defects of workpieces. The process of this method is to evenly apply a material called penetrant on the surface of the inspected workpiece, so that it penetrates into the defect, remove the excess penetrant after retaining it for a suitable time, and dry the workpiece, then apply a developer to absorb the penetrant that has penetrated into the defect, and then use appropriate observation methods to determine whether there are traces on the surface of the inspected workpiece.
2.2 The process parameters (such as pre-cleaning, penetration time, etc.) are determined by the specific materials used, the characteristics of the inspected workpiece (such as size, shape, surface state, alloy material), and the expected defect type. The liquid penetrant inspection method can indicate whether there are defects and their locations, and to some extent, their nature and size.
2.3 The types of liquid penetrant inspection methods are shown in Table 1. Method A is called the fluorescent penetrant method, which is divided into A-1, A-2, and A-3 methods according to the characteristics of the penetrant; method B is called the color penetrant method, which is divided into B-1, B-2, and B3 methods according to the characteristics of the penetrant. Table 1 Liquid penetrant inspection methods and their classifications
Method A Fluorescent liquid penetrant inspection
Type 1 - water wash type (operation method A-1) Type 2 - post-emulsification type (operation method A·2) Type 3 - solvent removal type (operation method A-3) 3 Types of materials used and inspection methods
3.1 Requirements for materials used
Method B - dyed liquid penetrant inspection
Type 1 - water wash type (operation method B-1)
Type 2 - post-emulsification type (operation method B-2) Type 3
Solvent removal type (operation method B3)
Materials used for liquid penetrant inspection include fluorescent and dyed penetrants, emulsifiers (oil-based plus water-based, fast reaction and slow reaction), detergents and developers. A group of applicable liquid penetrant inspection materials consists of penetrants, emulsifiers, detergents and developers recommended by the manufacturer. It is recommended not to mix penetrant inspection materials produced by several manufacturers, and be careful that the materials do not have a harmful effect on the workpiece being inspected. It is recommended to use a comparison test block to identify the performance of the material before use. 3.2 Fluorescent penetrant inspection method (Method A) and types of penetrants Fluorescent penetrant inspection is a method of observing defect traces through stimulated fluorescence under the action of ultraviolet light. The sensitivity of the fluorescent penetrant depends on the ability of the penetrant to remain in defects of various sizes during the inspection process, and the brightness of the penetrant that seeps into the developer coating and produces fluorescent display.
3.2.1 Water-washable penetrants refer to those that can be directly washed with water after a suitable penetration time. Since this type of penetrant is an emulsifier "mixed" into the water-washable penetrant, it is critical to remove the excess penetrant on the surface of the workpiece while ensuring that it is not over-washed. Therefore, it is necessary to train qualified operators. 3.2.2 Post-emulsified penetrants refer to those that are insoluble in water and cannot be washed away with water. Instead, they require a special emulsifier that reacts with the excess penetrant after a suitable emulsification time to form a mixture that can be washed away with water. The appropriate emulsification time should be determined through experiments. 3.2.3 Solvent-removable penetrants refer to those in which excess penetrants can be wiped with clean, lint-free materials to remove most of the excess penetrants. The remaining penetrants can be wiped with a lint-free material dipped in a little detergent to remove all the excess penetrants. This type of penetrant is mostly used for portable and local area inspections. To prevent excessive cleaning, excessive use of solvents should be avoided and direct washing of the workpiece surface with solvents is prohibited.
3.3 Color penetrant inspection method (B method) and types of penetrants Color penetrant inspection is a method of inspection using penetrants that can be visually observed under visible light. The penetrants used are mostly red, which contrast with the developer with a white background to show obvious traces. This method does not require black light, but must be observed under sufficient white light. 3.3.1 Water-washable color penetrants refer to penetrants with the functions described in 3.2.1. 3.3.2 Post-emulsified color penetrants refer to penetrants with the functions described in 3.2.2. 3.3.3 Solvent-removable color penetrants refer to penetrants with the functions described in 3.2.3. 3.4 Emulsifiers and types
Emulsifiers are liquids used to emulsify excess oily penetrants on the surface of workpieces, and can be washed off with water after emulsification. There are two types of emulsifiers; oil-based and water-based (containing detergents). Depending on the surface condition, viscosity, concentration and chemical composition of the workpiece, both can emulsify within a few seconds to a few minutes.
3.4.1 Oil-based emulsifiers are usually available for use. The speed of the emulsification reaction depends on its own viscosity and chemical composition. High viscosity generally works slower than low viscosity. Its function is to diffuse (dissolve) into the excess penetrant on the surface of the workpiece and emulsify it. The speed of diffusion determines the time of emulsification. 3.4.2 Water-based emulsifiers (including detergent types) are generally supplied diluted with water and are used by splashing or pouring. Its function is to remove excess penetrant film on the surface of the workpiece through washing. When detergent is used to remove the penetrant film, the force of the water spray or the air agitation in the open immersion tank acts as a scrub, and the emulsification time should be determined according to the concentration of the detergent in the water. 3.5 Cleaning Agents
The function of the cleaning agent is to dissolve the penetrant so that the surface can be wiped clean without leaving excess penetrant. 3.6 Developers
The function of the developer is to absorb the penetrant that has penetrated into the defect through the adsorption of the coated developer and display it on the surface of the workpiece, thereby showing the signs of the penetrant and enhancing the clarity of the signs. 3.6.1 Dry developer (i.e., unbaked free-flowing powder) is purchased and used according to the method of 4.7.5. Care should be taken not to allow fluorescent penetrant to contaminate the developer, because contaminated spots will be treated as defects. 3.6.2 Wet water-suspended developer, depending on its type, is usually supplied in two states: dry powder suspended in water or dissolved in water. 3.6.2.1 A water-suspended developer is a suspension of developer particles suspended in water. Its concentration, method of use and storage should be carried out in accordance with the manufacturer's instructions (see 4.7.6).
3.6.2.2 A water-soluble developer is prepared with a soluble powder that dissolves in water and is used at the concentration recommended by the manufacturer's instructions (see 4.7.6).
3.6.3 A non-aqueous suspension developer is prepared with developer particles suspended in a non-aqueous solvent carrier. It is very convenient to use. After removing excess penetrant from the workpiece and drying the workpiece, spray this developer on the workpiece with an ordinary or electrostatic spray gun, or spray it with a pressure tank. After drying, this developer forms a white coating on the surface of the workpiece to set off the penetrant. 3.6.4 Film-type developer, this type of developer is a solution or a colloidal suspension of resin and polymer. This type of developer will form a transparent or translucent coating on the surface of the workpiece. Some types of coatings can also be peeled off from the workpiece for data preservation. 4 Operation method
4.1 Temperature requirements
JB/T 8466--96
The following general operation method (see Figure 1) is applicable to fluorescent and dye penetrant inspection methods. As a standard method, the temperature of the penetrant and the workpiece surface should be between 15 and 50°C. When the actual situation is inconsistent with this temperature limit, the operation at the actual temperature should be re-evaluated.
Input work
To clean
Remove excess penetrant
Final cleaning
Mechanical
A-1 and R-1 methods
Apply water-washable
Penetrant
Water rinse
Detergent
Developer
(Water-suspended type)
Dry developer
(Dry or water-based)
Water rinsewwW.bzxz.Net
Vapor degreasing
Vapor degreasing
A--3 and B-3 methods
Apply solvent-sensitive
Washable penetrant
Solvent wipe
Developer
(Dry or non-aqueous)
Detergent
Output workpiece
Ultrasonic
Apply emulsifier
Solvent rinse
Method A-2 and B--2
Apply emulsifier
Penetrating agent
Water rinse
Dry developer
(Dry or non-aqueous)
Paint wash
Apply cleaning agent
Developer
(Water suspension type)
Mechanical rinse
Surfing agent immersion
Figure 1 Penetrant test flow chart
Ultrasonic cleaning
4.2 Surface condition before penetrant test
JB/T 8466--96
Surfaces in the welded, cast, forged, and rolled state can usually be inspected. However, surface irregularities will mask the indication of rejection defects. When the inspection effect is affected, the surface to be inspected must be prepared by means of machining, cleaning, etc. (see Appendix A (Standard Appendix)). 4.3 Cleaning of the inspected surface
4.3.1 Pre-cleaning
The success of any penetrant inspection operation depends largely on the presence of contaminants on the surface and in the defects that hinder the entry of the penetrant. For this reason, all inspected parts or areas should be cleaned and dried before applying the penetrant. "Cleaning" means removing all contaminants that may hinder or interfere with the penetration of the penetrant into the defect, such as rust, scale, welding slag, spatter, grease, paint, oil film, dirt, etc. Cleaning residues will have a detrimental effect on the penetrant, thereby greatly reducing the sensitivity and performance of the penetrant. Acids and chromates will seriously reduce the fluorescence of many penetrants. If a part of the workpiece is to be inspected, for example a strip weld area, the area adjacent to the surface to be inspected shall be cleaned within at least 25 mm.
4.3.2 Drying after cleaning
The cleaned workpiece shall be dried, as any residual liquid will prevent the penetration of the penetrant. Drying methods include heating the workpiece in a drying oven, baking with infrared lamps, blowing with hot compressed air or drying at ambient temperature. However, the temperature of the workpiece shall not exceed 50°C before the penetrant is applied.
4.4 Application of penetrant
After the workpiece has been cleaned, dried and cooled to near ambient temperature (not higher than 50°C), the penetrant is applied to the surface to be inspected so that the workpiece or area to be inspected is completely covered with the penetrant.
4.4.1 There are many effective methods for applying the penetrant, such as immersion, brushing, dripping or spraying. Small workpieces are often placed in a suitable hanging basket and immersed in the penetrant. Larger workpieces and workpieces with complex shapes can be coated by brushing or spraying. Conventional spray guns and electrostatic spray guns are effective tools for applying penetrants to workpieces. Electrostatic spraying can eliminate the accumulation of excess penetrant on the workpiece and avoid serious seepage problems during workpiece inspection. Air suspension spraying is also very effective and a very convenient spraying method. When using this spraying method, special attention should be paid to ventilation. The general practice is to carry out the spraying in a dedicated spraying plant or add ventilation equipment. 4.4.2 The length of time that the penetrant penetrates (resides) on the workpiece is recommended by the manufacturer. Table 2 provides the principles for selecting the penetration time for various materials, material conditions and defect types to be inspected. If the excess penetrant is difficult to remove due to the extended penetration time, the penetrant should be reapplied and the penetration time should be controlled. 4.5 Removal of excess penetrant
4.5.1 After the required penetration time, remove the excess water-washable penetrant as described in 4.5.2, remove the excess emulsifiable penetrant as described in 4.5.3, and remove the solvent-removable penetrant as described in 4.5.4. 4.5.2 Water-washable penetrants can be directly washed with water without the need for an emulsification process. Automatic, semi-automatic, manual water spray or immersion device can be used to remove excess penetrant during washing. The degree and speed of removal depend on the following parameters: water pressure, water temperature and duration of washing; the inherent cleaning properties of the penetrant used and the surface condition of the workpiece also affect the speed and degree of removal. For this reason, the water washing operation should be carried out under controlled conditions. 4.5.2.1 The water pressure must be constant and must not exceed 345kPa (the average value is 205kPa). It is usually recommended to use a large stream of water. 4.5.2.2 Keep the water temperature relatively constant. Most water-washable penetrants can be removed at a water temperature of 1545℃. In order to achieve better results, the temperature should be kept within the range recommended by the manufacturer. 4.5.2.3 The duration of washing depends on the inherent cleaning performance of the penetrant, the surface condition of the workpiece, and the water spray pressure and temperature used. In special applications, it is determined by experiments. The best time is when there is no residual penetrant that hinders observation. 4.5.2.4 Avoid excessive washing. Excessive rinsing will wash the penetrant away from the inside of the defect. Performing the A-method rinsing operation under black light can monitor the status and time of penetrant removal from the surface. 4.5.2.5 In special applications, if there is no suitable water washing device, a clean hygroscopic material can be used to wipe the penetrant on the surface until the penetrant is removed. 4.5.3 Post-floating penetrants cannot be directly rinsed with water. This type of penetrant requires an emulsifier (oil-based or water-based) to be used after penetration. The required emulsifier is spread, dripped or sprayed on the workpiece to emulsify the excess penetrant on the workpiece. After applying the emulsifier, remove the workpiece in one way to prevent the emulsifier from accumulating on the workpiece. 4.5.3.1 The residence time of the emulsification reaction begins after the emulsifier is applied. The emulsification time allowed for the emulsifier on the workpiece is determined by the type of emulsifier (fast reaction, slow reaction, oil-based or water-based) and the surface condition of the workpiece (smooth or rough). The standard emulsification time is recommended by the emulsifier manufacturer. Each specific emulsification reaction time is determined by experiments. Surface roughness is an important factor in selecting an emulsifier and determining the length of the emulsification reaction time. The general emulsification reaction time is determined by the activity of the emulsifier and can be in the range of seconds and minutes. Table 2 Recommended dwell time
A--1, A--2.A--3
B---1, B--2, B--3
Inspected materials
Aluminum, magnesium, copper, brass and bronze, titanium
Cast - castings and welds
and high-temperature alloys
Forged extrusions, forgings,
Carbide insert tools
Temperature range 15~50℃,
various states
various states
various states
2The dwell times given are the recommended minimum values. Defect types
All forms of cold shut, looseness,
Incomplete penetration, cracks
All forms of heavy skin, cracks
Incomplete welding, looseness, cracks
3 The appearance time is calculated from the moment the dry developer or wet developer coating is dried on the workpiece. The residence time of the method
Penetrating agent
Developer
4.5.3.2 The methods for washing the emulsified penetrant from the workpiece surface include: manual, semi-automatic or automatic water spray or flooding. The residual penetrant must be extremely small, so as not to affect the observation of the workpiece soil display and not to over-emulsify. 4.5.4 Removal of excess solvent removal penetrant, use a clean, lint-free cloth to wipe off most of the excess penetrant as much as possible, and then use the cloth to slightly dip in solvent and wipe the workpiece surface until the excess penetrant is completely removed. In order to avoid removing the penetrant that has penetrated into the defect, it is forbidden to rinse the workpiece surface with solvent after applying the penetrant and before the defect is imaged. 4.6 Drying of workpiece
4.6.1 During the preparation of the surface to be inspected, the workpiece shall be dried after the application of the wet developer or before the application of the dry developer. 4.6.2 The workpiece may be dried in a hot air circulation oven, by hot air blast, or at ambient temperature. Drying is best performed in a constant temperature hot air dryer. The temperature in the dryer is usually maintained between 80 and 110°C. Unless otherwise agreed between the supplier and the purchaser, the workpiece temperature shall be maintained between 15 and 50°C.
4.6.3 The workpiece shall not be allowed to remain in the drying oven for longer than is necessary for the workpiece to dry. Long residence time in the dryer will cause damage to the workpiece and evaporation of the penetrant, which will reduce the sensitivity of the inspection. Drying time varies with the size, nature and number of the workpieces to be inspected. 4.6.4 In the case of solvent-removable penetrants, excess penetrant shall be removed by solvent wiping and the surface shall be dried by general evaporation methods. No other methods shall be used to dry the surface. The temperature shall be between 15 and 50°C throughout the process. 4.7 Application of developer and display of defects
4.7.1 The display process of penetrant is to absorb the penetrant that has penetrated into the defect through the adsorption of the developer and display it on the surface of the workpiece to increase its visual visibility.
4.7.2 Whether dry or wet developer is applied, it should be evaporated to dryness before visual inspection to form suspended particles or resin (polymer) liquid film.
4.7.3 The application of water-based developer is carried out immediately after the excess penetrant is removed from the workpiece, while other types of developers are applied after drying.
JB/T8466—96
4.7.4 There are many ways to apply various developers, such as dipping, immersion, showering, spraying or powdering. The selection of the application method should depend on the size, shape, surface condition, quantity and other factors of the inspected workpiece. 4.7.5 The application of dry developer is carried out after the workpiece is dry. The application method includes immersing or dipping the workpiece in a dry powder developer container or in a fluidized bed of dry powder developer, or using a manual powder remover or powder spray gun. The most common method is to apply dry powder developer in a closed powder removal chamber because such a closed chamber can provide a controllable powder cloud. Excess powder particles can be removed by gently shaking and tapping the workpiece, or by blowing with low-pressure (25-70kPa) dry and clean compressed air, or by spraying with ordinary or electrostatic powder spray guns. 4.7.6 Water-based developer is applied immediately after the excess penetrant is removed and before drying. The dried developer forms a self-colored coating on the surface of the workpiece. The application method is implemented according to the manufacturer's instructions. 4.7.6.1 The water-based developer is applied to the workpiece by spraying, pouring or dipping. The most common method is to immerse the workpiece in a prepared developer tank. The workpiece shall be immersed for a time sufficient to allow the developer to cover the entire surface of the workpiece. The workpiece shall then be removed from the developer tank and allowed to flow.
4.7.6.2 The workpiece shall then be dried according to 4.6.
4.7.7 After the excess penetrant on the workpiece has been removed and dried, a non-water-based wet developer shall be sprayed on the workpiece. This developer is very easy to evaporate at room temperature, so a dryer is not necessary, but it must be carried out under ventilated conditions. 4.7.7.1 The non-water-based developer shall be sprayed according to the manufacturer's recommended spraying method, that is, a thin and uniform film of developer shall be ensured to cover the entire workpiece.
4.7.7.2 The non-water-based developer shall not be used to immerse or shower the workpiece, because immersion or showering will dissolve the penetrant from the defect. 4.7.8 Liquid film-type (peelable) developers should be applied by spraying or dipping according to the manufacturer's recommendation to ensure that the workpiece surface is covered with a thin and uniform developer film. 4.7.9 The developer should be retained on the workpiece for no less than 7 minutes before visual observation. Generally, dry or wet developers (water-based and non-water-based) should be observed immediately after application (the solvent carrier has evaporated at this time). If there is no penetrant seepage during observation, the development time is allowed to exceed 30 minutes.
4.8 Observation of display
Observation of display shall be in accordance with 4.7.9. After an appropriate development time, that is, after ensuring that the penetrant has reversely seeped from the defect to the developer coating layer, the workpiece can be observed. When applying a developer that helps to judge the display, it is a good method to pay attention to the changes in the surface. 4.8.1 Observe the display of fluorescent penetrant in a darkroom. For inspections with high requirements, the maximum illuminance allowed in the darkroom is 301x. For inspections with low requirements, the illuminance can be higher than the above value in a darkroom. 4.8.1.1 The intensity of black light is measured with a black light meter. The recommended minimum black light intensity value for the surface of the inspected workpiece is 800uW/cm. Check the black light intensity regularly (recommended once every 30 days) to ensure the required output power. Network voltage drop will reduce the black light output power, so it should be checked regularly. If the black light characteristics often change due to network voltage fluctuations, a voltage stabilizer should be used. 4.8.1.2 The light intensity of the black light needs to be measured before use, but it should be heated for at least 5 minutes. 4.8.1.3 The inspector should stay in the darkroom for at least 5 minutes before observation to adapt his eyes to working in the darkroom. 4.8.1.4 Keep the darkroom free of debris that may hinder observation. Keep the work area clean at all times. 4.8.2 The display of the colored penetrant can be observed under natural light or artificial white light, but appropriate light is required to ensure the sensitivity of the inspection. The recommended illumination in the inspection room is at least 3501x. 4.9 Final Cleaning
Final cleaning is necessary in the following cases, that is, when residual penetrant or developer will hinder the subsequent process or use requirements; when residual penetrant on the inspected workpiece combined with other factors will cause corrosion. Cleaning methods include water cleaning, mechanical washing, vapor degreasing, solvent immersion or ultrasonic cleaning (see A1.2.5). If the developer must be cleaned after inspection, it should be done immediately after inspection. Generally, water spray flushing is used.
Note: The developer should be removed before vapor degreasing, because vapor degreasing will bake the developer on the workpiece. 5 Special requirements
5.1 When penetrant testing is used for austenitic stainless steel and titanium-nickel based alloy materials, the chloride and fluoride ion content and the total nitrogen, fluorine and sulfur content should be limited. If there is such a requirement, the contracting parties shall reach an agreement on the sampling technology, analytical test methods, and the limit values ​​of chlorine, fluorine and sulfur content. If there is no special requirement, the chlorine content shall be limited to less than 1%, and the same applies to fluorine and sulfur. 5.2 When penetrant testing is performed on the workpiece, the temperature must be kept within a range. When it exceeds the upper and lower limits specified in 4.1, special materials and operating techniques must be used. At the same time, these special materials and operating techniques must be identified in accordance with the method of 6.1, and the manufacturer's recommendations must be followed. Identification and fumigation identification
6.1 Identification of the effectiveness of penetrant materials and operations·Determined by direct comparison of liquid penetrant comparison blocks selected by the contracting parties or on representative workpieces to be inspected.
6.2 If the type of penetrant material or the operating technique changes, requalification is required. 469
A1 Selection of cleaning method
JB/T 8466—96
Appendix A
Cleaning of inspected workpieces and materials
(Standard Appendix)
A1.1 Selection - A suitable cleaning method should take into account the following factors: a) The type of contamination to be removed, because no cleaning method can clean all contamination h) The effect of the cleaning method on the workpiece:
c) The practicality of the workpiece cleaning method (for example, a large workpiece cannot be placed in a small degreasing or ultrasonic cleaner); d) The specific cleaning requirements of the material to be inspected.
A1.2 Recommended Cleaning Methods
A1.2.1 Detergent Cleaning
Detergents are non-flammable water-soluble compounds containing specially selected surfactants, which are used to wet, penetrate, emulsify and saponify various types of contamination, such as grease, cutting or machining liquids, lubricants, etc. Detergents can be alkaline, acidic or neutral, but must be non-corrosive to the workpiece being inspected. The cleaning performance of the detergent solution should be easy to completely remove dirt and contamination from the surface and cavity areas of the workpiece, preparing for the adsorption of penetrants. The cleaning time is an average of 10 to 15 minutes, the temperature is 75 to 80°C and it must be stirred slowly. The concentration used is the concentration recommended by the manufacturer (-generally 4560kg/m2). A1.2.2 Solvent Cleaning
Many solvent cleaners can dissolve such as grease, oil film, wax, sealant, paint and general organic matter. These solvents should be residue-free. It is recommended not to use solvent cleaners to remove rust, scale, flux, spatter and inorganic pollution. Note: Some cleaners are flammable and toxic. You must understand the manufacturer's instructions and safety precautions. A1.2.3 Vapor degreasing
Vapor degreasing is from I.Remove oil or grease type contamination (dirt, rust, salts, etc.) from the surface and opening defects of the parts. However, it is impossible to remove resin contamination (plastic coverings, enamels, paints, etc.) because it is impossible to completely degrease deeper defects with a short contact time, so it is recommended to soak with solvents.
A1.2.4 Alkaline Cleaning
A1.2.4.1 Alkaline cleaners are non-flammable aqueous solutions containing specially selected detergents, which are used to wet, penetrate, emulsify, and saponify various types of contamination. Hot alkaline solutions can remove rust and scale that mask surface defects. The composition of alkaline cleaners must be used according to the manufacturer's recommended instructions.
Note: Workpieces cleaned with alkaline cleaning must be thoroughly rinsed until there is no cleaning agent, and the workpieces must be heated and thoroughly dried before penetrant inspection operations. The workpiece temperature must not exceed 50°C when the penetrant is applied. A1.2.4.2 Steam cleaning is a modified form of hot tank alkaline cleaning. This method can clean large and bulky workpieces and remove inorganic and many organic contaminants from the surface of the workpiece, but it is unlikely to reach the bottom of deeper defects. Subsequent solvent soaking is recommended. A1.2.5 Ultrasonic Cleaning
This method adds ultrasonic agitation to solvent or detergent cleaning to improve cleaning results and shorten cleaning time. If the contamination to be removed is inorganic (rust, dirt, salts, corrosion products, etc.), water and detergent should be used. If the contamination to be removed is organic (grease, oil film, etc.), organic solvents should be used. After ultrasonic cleaning, the workpiece should be heated to remove the cleaning solution and the workpiece should be cooled to at least 50°C before applying the penetrant.
A1.2.6 Paint Removal
Paint and oil film removal is very effective using adhesive stripping solvents or separate hot tank alkaline paint removers. In most cases, the paint and oil film must be completely removed to expose the metal surface. Solvent-based paint removers can be applied by spraying or brushing. The operating temperature is generally 470°C JB/T8466--96°C ambient temperature. Hot tank alkaline paint removers are water-soluble powder compounds. The operating temperature is 80~95°C and the concentration is 60~120kg/cm. After paint removal, the workpiece should be thoroughly rinsed, all contamination should be removed from the open gaps and then thoroughly dried. A1.2.7 Mechanical cleaning and surface finishing Metal cutting cleaning methods, such as filing, polishing, scraping, milling, drilling, reaming, grinding, liquid grinding, turning or vibration burring. Sand blasting can be used to remove carbon, rust, scale, casting sand and chamfering. These methods may dirty the surface to be inspected, especially soft metals such as aluminum alloys, titanium alloys and magnesium alloys, which will fill the openings of defects to the surface and reduce the effect of penetrant inspection. A1.2.8 Pickling is primarily used to remove scale from the surface of a workpiece, since scale masks surface defects and prevents penetration of the penetrant. Acid solutions and etchants are also commonly used to remove metal from surface discontinuities covered by hammering. NOTE: Etches should be used in accordance with the manufacturer's recommended instructions. NOTE The material or workpiece under examination must be rinsed free of etchant and the surface heated to dry thoroughly before penetrant application. Acids and chromates can adversely affect the luminescence of fluorescent materials. The use of acid solutions and etchants may, however, result in the introduction of hydrogen, so the workpiece should be baked at an appropriate concentration for 2 hours to remove hydrogen before further processing. A1.2.9 Heating Ceramics in Air Heating ceramic workpieces in a clean, oxidizing atmosphere is an effective method for removing moisture or light organic contamination, or both. The heating temperature should be limited to the highest temperature that does not degrade the performance grade of the ceramic. A2 Final Cleaning
A2.1 Dry powder developers may be blown off with air (oil-free); wet developers may be removed by water rinsing or by hand or mechanical washing with water containing detergent; solvent-removable developers may be simply dissolved away with water. A2.2 Residual penetrant may be removed by dissolution. Vapor degreasing (at least 10 minutes), solvent immersion (at least 15 minutes), and ultrasonic solvent cleaning (at least 3 minutes) are recommended methods. In some cases, it may be desirable to use vapor degreasing followed by solvent immersion. The time required for this method will depend on the nature of the workpiece and will be determined by experiment. 471
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