JB/T 5072-1991 General technical requirements for heat treatment protective coatings
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T5072--91www.bzxz.net
Heat Treatment Protective Coating
General Technical Requirements
Published on 1991-06-11
Published by the Ministry of Machinery and Electronics Industry of the People's Republic of China
Implemented on 1992-07-01
Mechanical Industry Standard of the People's Republic of China
Heat Treatment Protective Coating
General Technical Requirements
Subject Content and Scope of Application
JB/T507291
This standard specifies the general technical requirements, use methods, inspection methods, quality control and storage and transportation conditions of metal heat treatment protective coatings. This standard is applicable to various protective coatings for structural steel, tool steel, stainless steel, high temperature alloy and titanium alloy parts. 2 Reference standards
Method for determining the depth of decarburized layer of steel
GB1723
Method for determining the viscosity of coatings
GB1724Method for determining the fineness of coatings
3 Technical requirements
3.1 During the heat treatment process, the protective coating shall, according to the different requirements of the parts, have the ability to obviously prevent or reduce oxidation of the protected metal, and prevent the depletion or infiltration of alloy elements on the surface of the parts. It shall have the ability to resist the depletion and infiltration of alloy elements for stainless steel, high-strength alloys and titanium alloys. It shall have a certain anti-decarburization ability for structural steel and tool steel, and shall generally be able to meet the ability that the total decarburization layer depth is less than or equal to 0.075mm.
3.2 The viscosity of the protective coating shall be 25-65s, and shall be determined by using a coating-4 viscometer according to GB1723. 3.3 The fineness of the raw materials in the protective coating shall not be greater than 45um, and shall be determined according to GB1724. 3.4 The protective coating should not have lumps and should have good wettability to the protected metal. When used, it should be sprayed, applied or diffused. The coating should be even, complete, without tumor marks, and have good adhesion. 3.5 The coating should be able to dry within 2 hours under room temperature and within 30 minutes within the range of 60100℃. 3.6 The coating should have good peeling performance. After the parts are water-cooled, more than 90% of the coating area should be able to fall off by itself; after oil cooling, more than 80% of the coating area should be able to fall off by itself. The residual coating should be easy to remove and the fallen coating should not contaminate the ignition medium. 3.7 The protective coating components should not contain elements that damage or contaminate metal parts. No harmful gases or substances should be released during the heating process. 4 Usage
4.1 Parts
The surface of the parts to be protected must be clean and free of rust, oil, dirt, etc. It can be cleaned by sandblasting or cleaning agents. After cleaning, it should be covered in time.
4.2 Coating
4.2.1 The coating should be fully stirred and evenly mixed.
4.2.2 If there are coarse particles, use a 200-mesh screen to filter before use. 4.2.3 Depending on the coating method, the coating can be adjusted to the required viscosity with a solvent: dip coating or spray coating 20~65ss
Approved by the Ministry of Machinery and Electronics Industry on June 11, 1991 and implemented on July 1, 1992
4.3 Coating
JB/T5072—91
4.3.1 According to the size, shape and area of the protected parts, the coating method, preparation coating method or spraying method can be used. 8. No coating method - suitable for the overall protection of small parts with simple shapes or the local protection of the ends. Slowly immerse the protected part of the part in the coating solution, stay for 10 to 20 seconds, then slowly lift it up, and use or scrape off the excess coating solution from the bottom of the part.
b. Brushing method - suitable for the local protection of large parts. Use soft hair to evenly apply, and do not use too much force. c. Spraying method - suitable for the overall protection or local protection of complex shapes and large and medium parts. Spraying can be evenly applied with a paint spray gun, and the wind pressure is 0.2 to 0.4MPa. 4.3.2 To ensure that the coating is even, dense and complete, it can be applied multiple times. When applying multiple times, the next coating must be applied after the previous coating is dry, and the degree of drying should be based on the principle of no sagging. When brushing multiple times, the direction of the next coating should be perpendicular to the previous direction. 4.3.3 The coating thickness should be determined according to the process requirements and coating properties. Under normal circumstances, it can be controlled at 0.1-0.5mm. 4.4 Drying of coating
The applied coating must be fully dried. The drying time at room temperature shall not be less than 2h; the drying time at 60-100℃ shall not be less than 30min. 4.5 Removal of residual coating
The coating remaining on the piano parts can be removed by sandblasting. 4.6 Process control
4.6.1 According to the type of protected material and the requirements of heat treatment process, the coating should be reasonably selected. 4.6.2 The operator should wear clean gloves to prevent the cleaned parts from being contaminated again to ensure the adhesion between the coating and the metal. 4.6.3 The compressed air used for spraying should be filtered to ensure that it is oil-free and water-free. The recommended inspection method is: use a 70mm×100mm (thickness is not limited) clean and dry aluminum alloy as a test plate. Aim the nozzle of compressed air with a center distance of 200-250mm. Open the compressed air to impact the surface of the test plate for 15 to 30 seconds, and visually inspect the test plate. If there is no oil or water, it is qualified. 4.6.4 The dried coating must be uniform, dense, complete, without cracks, bubbles, peeling, and residue. The thickness and uniformity of the coating should meet the process requirements and can be measured by lever dry ruler or magnetic thickness gauge. 4.6.5 The coated parts should be prevented from collision and contact with oil during placement, transportation, and furnace loading. If cracks or shedding of the coating are found, repair is allowed.
4.6.6 After the coating is dried, the parts should be protected from moisture and heat treatment should be carried out in time. Generally, the storage should not exceed 48 hours. 4.6.7 When using the coating, there should be exhaust equipment and attention should be paid to fire prevention. 5 Coating performance inspection method
5.1 Inspection sample
The material used for the inspection sample must be the same as the part, the surface roughness R is 3.2um, and there must be no decarburization layer and oxidation color. The process of joining parts requires coating to the specified thickness. After the coating is dry, the sample is heat treated with the parts in the same furnace and process. 5.2 Anti-oxidation performance
A test plate of 100mm×100mm (unlimited thickness) or a test front of 45~20mm can be used. After heat treatment, the surface of the sample should be checked with a 10x magnifying glass. There should be no corrosion and obvious oxidation color. 5.3 Anti-decarburization performance
After heat treatment, according to the requirements of GB224, the total decarburization layer depth is determined by metallographic method or hardness method. The result should meet the requirements of Article 3.1. 5.4 Resistance to alloy element chemical and element penetration performance After heat treatment, the sample can be inspected by chemical analysis or electron probe analysis according to the specific situation. The result should be free of alloy element depletion and element penetration.
5.5 Coating peeling performance
The coating peeling area ratio is calculated as follows: JB/T5072-91
The area of the sample substrate surface that is out of the way×100% coating peeling area ratio!
Total surface area of the sample
6 Coating quality control
6.1 Coating production must be carried out strictly in accordance with the formula and relevant process regulations. 6.2 When there is a major change in the source of raw materials, formula, and process of the coating, the user should be notified. 6.3 The user reserves the right to re-test the purchased coating according to this standard. 7 Marking, packaging, storage and transportation
7.1 The packaging and transportation of the coating should comply with the relevant national transportation regulations. 7.2 The coating packaging should be clearly marked. The content includes: product name, trademark, safety mark, net weight batch number and manufacturer. 7.3 The coating package should contain a product certificate and instructions for use. The certificate includes: product name, standard number, model, grade, batch number, inspector number, production date and validity period; the instructions for use should include: use temperature, time, protected material, diluent name, use viscosity, use method and precautions during storage and transportation. 7.4 Coatings containing organic solvents should be sealed during storage and placed in a ventilated and cool place. They must be kept away from heat sources and must not come into contact with open flames. Additional notes:
This standard was proposed by the National Technical Committee on Heat Treatment Standardization. This standard is under the jurisdiction of the Wuhan Materials Protection Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by the 621 Institute of the Ministry of Aeronautics and Astronautics, the 410 Factory and the Xi'an Paint Factory. The drafters of this standard are Zhang Wenshang, Jie Lanying, Duan Xuhai, Wang Zhenru and Fan Guibin.
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