This standard specifies the technical specifications, quality requirements and inspection methods for chemical oxidation films on steel parts. This standard applies to the quality inspection and acceptance of high-temperature alkaline chemical oxidation films on steel. Similar films obtained by other methods can also be used as a reference. GB/T 15519-1995 Chemical Oxidation Film on Steel GB/T15519-1995 Standard download decompression password: www.bzxz.net
This standard specifies the technical specifications, quality requirements and inspection methods for chemical oxidation films on steel parts. This standard applies to the quality inspection and acceptance of high-temperature alkaline chemical oxidation films on steel. Similar films obtained by other methods can also be used as a reference.

National Standard of the People's Republic of China
Chemical oxide coating for iron and steel
The chemical oxide coating for iron and steel1 Title Content and Scope of Application
GB/T 15519—1995
This standard specifies the technical specifications, quality requirements and inspection methods for chemical oxidation treatment films on steel parts. This standard is applicable to the quality inspection and acceptance of high-temperature alkaline chemical films on steel. Similar films obtained by other methods can also be used for reference. 2 Reference Standards
GB2423.3 Electric King Electronic Products Environmental Test Procedure Test Ca Constant Heat Test Method GR5936 Test Method for Chemical Protection of Ferrous Metals in Light Industrial Products Immersion Drip Method GB 6458 Neutral salt spray test for metal coating (NSS test) CB12609 Sampling inspection of electrodeposited metal coating and related finishing R12611 Technical requirements for pre-tax quality control of metal parts (components) chain 3 Definitions
Main surface: Certain oxidized or to-be-oxidized surfaces on the workpiece, the film layer on this surface is important to the appearance and (or) performance of the workpiece,
4 The purchaser shall provide the following information to the supplier:
The standard number of this standard:
Indicate the main surface on the order form or drawing, or provide samples with appropriate markings: b.
The brand, heat treatment and surface state of the base material; d.
Requirements for stress relief treatment before oxidation and hydrogen embrittlement relief treatment after oxidation: e.
Sampling method adopted:
Supplementary treatment method adopted.
5 Requirements for base materials before oxidation
5.1 Base materials
This standard does not specify the surface state, finish or surface roughness of base materials before oxidation. However, considering that the surface roughness of the oxide film depends on the original surface roughness of the base material, the defects caused by the original surface roughness of the base material do not constitute a reason for rejection of the oxide film:
5-2 Stress relief heat treatment
For cold-hardened base materials with a surface hardness greater than Vickers hardness HV340 (1050MPa), stress relief treatment should be carried out in accordance with the provisions of GB1261] before oxidation.
5.3 Pretreatment
Approved by the State Administration of Technical Supervision on April 2, 1995 and implemented on February 1, 1996
GE/T155191995
The base material should be properly pretreated before oxidation to improve the surface quality and eliminate surface rust, oil, scale or other impurities. 6 Oxidation treatment
Unless otherwise specified, oxidation treatment should be carried out after machining, forming, welding, cold correction and heat treatment are all completed. 6.1 Oxidation process
The oxidation process should be selected according to the grade and performance requirements of the base material. However, the oxide film obtained by the process should meet the technical requirements specified in this standard. When molten salt oxidation is used for corrosion-resistant alloy steel, the hardness of the processed part cannot be reduced, nor can the temper brittleness or alkali brittleness of the base material be caused.
7 Requirements for each piece after oxidation
7.1 Hydrogen embrittlement elimination treatment
For surface hardened parts (Vickers hardness HV340 or above), hydrogen embrittlement elimination treatment should be carried out within 4 hours after oxidation, with a treatment temperature of 100~-220℃ and a holding time of not less than 3 hours. 7.2 Supplementary treatment
In order to improve the protectiveness of the oxide film or achieve certain decorative effects, the oxide film should be supplemented. The specific requirements of the supplementary treatment process shall be agreed upon by the supply and demand parties.
8 Quality requirements for oxide film
8.1 Appearance
The oxide film should cover the surface of the workpiece evenly and completely. The following are the common colors of the oxide film: the chemical oxide film of carbon steel and low alloy steel should be black; the film obtained by sandblasting and chemical oxidation should be gray-black. a.
Due to different alloys or contents, the chemical oxide film of alloy steel can be red, purple, blue-black or light black. b.
The chemical oxidation film of cast iron and silicon steel products is yellowish black, and the chemical oxidation film of cast steel is dark brown. d
For parts treated by molten, nitrided or carburized, the film is grayish white, light red or rainbow. e
For parts treated by de-molding and re-oxidation: the film lip is allowed to be dull. The same batch of workpieces can have different colors and gloss due to different heat treatment and surface processing conditions. g.
It is not allowed to have red, green or white ash on the film (including the film treated by chromate sealing). h.
8.2 Wear resistance
If the buyer has requirements for the wear resistance of the film, the test method should be agreed upon by the supplier and the buyer. 8.3 Porosity and continuitybzxz.net
Oxalic acid test or copper sulfate test shall be carried out on the oxide film that has not been supplemented. After the copper sulfate test, the film layer with a gray center and a lighter periphery is an unqualified film, see Appendix A (Supplement) Figure A1; the film layer with a gray-black center and a lighter periphery is a qualified film, see Appendix A Figure A2. The film layer with a black or black center and a lighter periphery is a high-quality film, see Appendix A Figure A3. The film layer tested by copper sulfate should be visually inspected and no contact copper should be produced. When the results of the two tests are inconsistent, the oxalic acid test shall prevail. 8.4 Corrosion resistance
8.4.1 Humidity test
When the purchaser has requirements, the corrosion resistance of the oxidized and post-processed workpiece, or the sample processed together with the workpiece, shall be evaluated according to the humidity test proposed in GB2423.3, and the test duration is generally not less than 10d. No corrosive red rust is allowed on the surface of the workpiece or sample.
8.4.2 Neutral salt spray test
For the main surface of austenitic stainless steel without oil film or any other supplementary protective layer, the salt spray test specified in GB6458 shall be carried out according to GB/T 155191995
assessment, the exposure time is 96h, and no corrosive red rust shall appear on the test surface. 9 Acceptance and inspection
Unless otherwise specified, the supplier shall complete all quality inspection requirements specified in this standard. 9.1 Sampling
The inspection shall be carried out in accordance with the provisions of GB12609.
9.2 Inspection method
9.2.1 Appearance inspection method
The visual inspection shall be carried out under natural scattered light or reflected light white transmitted light, the illumination shall not be less than 3001x, the distance between the component and the naked eye shall be 350mm, and a 35x magnifying glass may be used for inspection when necessary. 9.2.2 Porosity and continuity test
Perform the test in accordance with the method specified in Appendix A or GB 5936. 9.2.3 Corrosion resistance test
Perform the test in accordance with the method specified in GB 2423.3 and GB 6458. 9.3 Inspection cycle
9.3.1 Appearance inspection cycle
Appearance inspection should be carried out batch by batch.
9.3.2 Destructive inspection cycle
The first batch of products or when the process is changed should be sampled for destructive testing. The sampling plan shall be in accordance with the provisions of Table 3 of Article 6.3 of CB12609. In addition, it shall be carried out in accordance with the agreement between the supply and demand parties.
10 Packaging, transportation and storage
Parts that have been chemically oxidized and supplemented should be packed in packaging boxes. During packaging, transportation and storage, they should be protected from damage, scratches, contamination and moisture.
GB/T 15519
Appendix A
Oxalic acid test method
[Supplement]
At room temperature, pour 30% oxalic acid (CHO4-2, chemically pure solution) onto the flat surface of the sample or component that has not been subjected to additional treatment after oxidation. After 8 days, rinse with water and check the sample by comparing it with the following figure. Whether it meets the requirements of Article 8.3...*
Figure A1 Unqualified film
Attached explanation:
A2 Qualified film
This standard is drafted by the National Metal and Non-metallic Covering Standardization Committee and the Wuhan Institute of Technology. The ten key specifications of this standard are Zou Banyou, Chen Gaoyin, Wei, and Li Shuangneng. Figure A: High-quality film
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