How to clean the stainless steel forging surface?

Stainless steel also forms oxide scale when heated, although it is not as thick as the oxide scale on carbon steel forgings, but the adhesion to the base metal is strong and hard, so that the die and cutting tool wear out quickly. Therefore, between billet making and final forging, the oxide scale must be cleaned before machining. The pickling and sandblasting used by Yongxinsheng are good cleaning methods, and the method of sand blasting after pickling the forgings is good.

Sandblasting is an effective method of mechanical cleaning and can be used for forgings of all sizes and shapes. For surfaces that are no longer processed or purified, only quartz sand blowing should be used. Shot blasting or grit can deface the surface and destroy corrosion resistance.

When hot forging stainless steel pipes are processed, due to the influence of some unfavorable factors, such as the outer surface is forged out of the pits when the oxide scale is not cleaned, the axis bending and the misalignment of each step of the steel pipe during the forging process, the decarburization layer caused by heating, the axis bending that may occur after forging heat treatment and the processing technology retention between the processes required by special machining requirements, etc., so the hot forging stainless steel pipe must leave a certain machining allowance. The axial machining allowance is generally only 4 6 mm at both ends of the larger diameter section. Among them, for both ends are forged, and the edges and corners of the steps are clear, take 4 mm; One end is forged, and the other end is the original blank (because the blanking has a horseshoe shape) or although it has been forged, the edges and corners of the step are unclear (such as the transition from small diameter to large diameter when forging with concave stops), take 6 mm.

If the diameter dimensions of each step are arranged in order from largest to smallest, the axial dimensions of the remaining small diameter segments are extended according to the nominal dimensions of the part. If the diameter size of each step is a concave block with alternating sizes, because the large diameter sections on both sides of the small diameter have left axial machining allowances, the axial dimensions of the forgings in the small diameter section should be the nominal axial size of the section minus the machining allowance at both ends of the large diameter section.

The solution was soaked in 71 82 for 5 60 min, and the pickling residue was removed, then thoroughly rinsed with water and dried. Spots or stains appear on the surface of stainless steel forgings after pickling passivation, which can be eliminated by scrubbing with fresh passivation solution or higher concentration of nitric acid.

Stainless steel forgings for ultimate pickling passivation should be protected and can be covered or wrapped with polyethylene film to avoid contact between foreign metals and non-metals. The treatment of acidic and passivated waste liquid shall comply with national environmental protection discharge regulations. For example, fluorine-containing wastewater can be treated with lime milk or calcium chloride.

The passivation solution does not use dichromate as much as possible, and if there is chromium-containing wastewater, it can be reduced with ferrous sulfate.

Yongxinsheng Forging would like to remind you here that pickling may cause hydrogen embrittlement of martensitic stainless steel forgings, if necessary, it can be oxygenated by heat treatment (heated to 200 degrees for a period of time).

Dear, there are three ways to deal with it.

1 Only stainless steel forgings or parts that have been pretreated can be pickled and passivated. 2 Pickling liquid pickling is mainly used for the overall treatment of small unprocessed parts of DAO, which can be sprayed and brushed. When the solution temperature is 21-60, check every 10 minutes or so until it shows a uniform white acid etching finish.

3 Pickling paste pickling is mainly suitable for large containers or local treatment. At room temperature, the pickling paste is evenly cleaned on the equipment (about 2-3mm thick), left for one hour, and then gently brushed with clean water or stainless steel wire brush until it shows a uniform white and acid-free finish.

1. Stainless steel has unique strength, high wear resistance, superior anti-corrosion performance and excellent characteristics such as not easy to rust. Therefore, it is widely used in the industry, food machinery, mechanical and electrical industry, land digging household appliances industry and home decoration, fine decoration industry. The application of stainless steel will be more and more extensive before the development of the early stage, but the development of stainless steel application is largely determined by the development of its surface treatment technology.

2. Cleaning and grinding: If there is damage, it should be polished, especially the scratches and splashes caused by the contact between the orange cover and the carbon steel parts, and the damage caused by slag cutting must be carefully and thoroughly cleaned and polished.

3. Mechanical polishing: appropriate polishing tools should be used for polishing, which requires uniform and consistent treatment, and avoids over-throwing and re-scratching.

4. Degreasing and dust removal: Before pickling and passivating stainless steel parts, oil, oxide scale, dust and other sundries must be removed according to the process.

5. Water sandblasting treatment: according to different treatment requirements, different micro glass beads, different process parameters, and avoid overspraying.

The surface of stainless steel is usually smooth, spraying paint on the surface, there will be a problem that the paint is easy to fall off, simply put, it can't stick, even if the paint is good, the stainless steel surface is not treated at all, and the adhesion is grade 0 when sprayed directly. If the paint is not suitable for stainless steel, it is sanded and the paint will still fall off. In fact, the problem we want to solve is not whether the stainless steel surface can be painted, but how to solve the problem of poor adhesion and paint off the stainless steel surface.

The quality of the decorative and protective effect of the coating is not only related to the properties of the metal substrate and the paint itself, but also has a direct relationship with the selection of the metal pretreatment process. The pre-coating treatment process and quality determine the adhesion between the coating and the substrate, and the adhesion is closely related to the protective performance of the coating.

There are many types of surface pretreatment methods for stainless steel metal substrates, which are mainly selected based on the structural characteristics, size, and output of the coated object. The main purpose of pretreatment is to remove foreign matter from the surface of the substrate and obtain a suitable surface roughness for better adhesion of the coating. The traditional surface pretreatment methods include grinding treatment, pickling passivation and sandblasting treatment, etc., with the development of technology, metal adhesion promoters are now commonly used to solve the problem.

Jiongsheng treatment agent stainless steel metal adhesion promoter is sprayed between the substrate and the paint coating, which plays the role of connecting the upper and lower levels, so that the substrate and paint coating on the hinge can achieve effective adhesion, improve the adhesion between the layers, and achieve the purpose of solving the problem of paint peeling. It is not only used for spraying the surface of stainless steel, but also widely used in the surface spraying process of zinc alloy, aluminum alloy and other materials to assist in strengthening the adhesion between the surface of the metal substrate and the paint coating.

Stainless steel surface treatment is commonly used.

There are several ways to deal with it:

surface whitening treatment; surface mirror glossing treatment; Surface tinting treatment.

Surface color whitening treatment: In the process of processing, stainless steel is coiled, edged, welded or heated by artificial surface roasting to produce black oxide scale. This hard gray-black oxide scale is mainly composed of two EO4 components, NICR2O4 and NIF, which were generally removed by strong corrosion methods of hydrofluoric acid and nitric acid in the past.

However, this method is costly, pollutes the environment, is harmful to the human body, and is more corrosive, so it is gradually eliminated. At present, there are two main methods for treating oxide scale: sandblasting (pill) method

It is mainly used to spray micro glass beads to remove the black oxide scale on the surface.

Chemical method: use a non-polluting pickling passivation paste and a non-toxic cleaning solution with inorganic additives at room temperature for immersion. So as to achieve the purpose of whitening the natural color of stainless steel.

After processing, it basically looks like a dull color. This method is more suitable for large, complex products.

Stainless steel surface mirror bright treatment method: according to the complexity of stainless steel products and different user requirements, mechanical polishing, chemical polishing, electrochemical polishing and other methods can be used to achieve mirror luster. The advantages and disadvantages of these three methods are as follows:

Surface coloring treatment: stainless steel coloring not only gives stainless steel products a variety of colors, increases the variety of products, but also improves the wear resistance and corrosion resistance of products.

There are several methods of coloring stainless steel:

chemical oxidation coloring method;

electrochemical oxidation coloring method; ionic deposition oxide coloring method; high-temperature oxidation coloring method;

Gas phase cracking coloring method.

A brief overview of the various methods is as follows:

Chemical oxidation coloring method: It is the color of the film formed by chemical oxidation in a specific solution, including dichromate method, mixed sodium salt method, vulcanization method, acid oxidation method and alkaline oxidation method. Generally, the INCO method is used a lot, but if you want to ensure the consistency of the color of a batch of products, you must use a reference electrode to control it.

Electrochemical coloring method: It is the color of the film formed by electrochemical oxidation in a specific solution.

Ion deposition oxide coloring chemical method: It is to put the stainless steel workpiece in a vacuum coater for vacuum evaporation plating. For example: titanium-plated watch cases, watch straps.

Generally golden yellow. This method is suitable for high-volume product processing. Because of the large investment and high cost, small batch products are not cost-effective.

High-temperature oxidation coloring method: It is to immerse the workpiece in a specific molten salt and keep it at a certain process parameter, so that the workpiece forms an oxide film of a certain thickness, and presents a variety of different colors.

Gas phase cracking coloring method: more complex, less used in industry.

Selection of treatment methods.

Which method to choose for stainless steel surface treatment should be treated according to the product structure, material, and different requirements for the surface.

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Polishing, passivation (to enhance the corrosion resistance of the product).

Mechanical polishing, pickling and electropolishing are all common methods of dealing with stainless steel, depending on the requirements, you are asking too unspecific, that's all.

Summary. Hello dear. The pretreatment of stainless steel forgings summarizes the following steps:

1) Mechanical leveling of the surface. Eliminate the roughness of the surface of stainless steel, and achieve a certain surface finish after mechanical grinding and polishing. (2) Degreasing.

Remove oil from the surface. (3) Pickling. Oxides are removed from the surface.

4) Weak corrosion. The surface is activated to be buried, and the surface passivation film is removed to expose the metal crystal structure.

Thank you. Hello dear. The pretreatment of stainless steel forgings summarizes the following steps:

1) Mechanical leveling of the surface. Eliminate the roughness of the surface of stainless steel, and achieve a certain surface finish after mechanical grinding and polishing. (2) Degreasing.

Remove oil from the surface. (3) Pickling. Oxides are removed from the surface.

4) Weak corrosion. The surface is activated to be buried, and the surface passivation film is removed to expose the metal crystal structure.

Stainless steel forgings refer to the objects in which the stainless steel material is subjected to pressure to shape the required shape or the appropriate compressive force through plastic deformation. This force is typically achieved through the use of a hammer or pressure. Through forging, the defects such as loose casting state generated by the metal in the smelting process can be eliminated, the microstructure is optimized, and the mechanical properties of forgings are generally better than castings of the same material due to the preservation of metal streamlines.

Forgings are mostly used for important parts with severe working conditions, except for plates, profiles or weldments that can be rolled with simple shapes.

In operation, the water sand cleaning machine or air pick is used to clean the casting waste sand. When the casting waste sand is cleaned, the cutting gun is operated in accordance with the regulations, and the casting gate, riser, flash and burr are cut.

The electrocutting link requires a lot of electricity, most of the foundries have a special headache for this, Dalian Aisennuo electromechanical equipment casting riser separation pliers, the use of hydraulic pressure to generate expansion force, to achieve the separation of the casting and riser, saving electricity and improving work efficiency!