Whether or not to be fully annealed after ductile iron casting 5

The landlord also needs to understand the process of machining, first of all, clarify the requirements for the use of the product, and determine the processing means of molding and the subsequent cold processing and heat treatment methods.

1. If the ductile iron is not processed and assembled after forming, heat treatment can be done.

2. If you need cold rough machining, you should do annealing before to improve the cutting performance, if necessary, in the annealing, remove the processing stress, depending on the situation, and then finish.

I, not a professional heat treatment expert, just understand some casting knowledge, I hope to help the landlord, the best landlord or check the information, consult the expert.

Depending on the product requirements, the general annealing methods of ductile iron include high-temperature graphitization annealing, low-temperature graphitization annealing, and isothermal quenching. Isothermal quenching is the best way to tap the properties of ductile iron!

Annealing will certainly help, but due to the maturity of the technology and cost constraints, it is now common to produce low-grade ductile iron in as-cast delivery.

It does not have to be determined according to the situation, if it is a plumbing part, it is generally more cast.

It depends on the performance requirements of the castings you produce. If the structure is more complex, it needs to be annealed, but if the structure is not complicated, it is not necessary. If the casting is directly cast, if the mechanical properties do not meet the requirements, it needs to be annealed by high-temperature graphitization.

Summary. 2.When the as-cast structure is F+P+G, and there is no free cementite, it is annealed at low temperature, heated to 720 760, kept warm for 3 6 hours, and slowly cooled to about 600 with the furnace, and then air-cooled out of the furnace.

It is softened annealing stress relief annealing 600-650, holding for 1-3 hours. The purpose of graphite iron annealing is to decompose the cementite in cast iron into graphite and ferrite. In the production of ductile iron, graphitization annealing heat treatment is commonly used to obtain high-toughness ferritic ductile iron.

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We're happy to answer for you! The reply to your question about the Qingqing faction is as follows: The annealing process of annealing ductile iron is as follows:

1.When there is not only pearlite but also free cementite in the as-cast structure, high-temperature annealing should be carried out. Heating 900 950, heat preservation for 2 5 hours with the furnace slowly cooling to about 600, out of the furnace air cooling.

2.When the positive absolute structure of the casting core is F+P+G, and there is no free cementite, it is annealed at low temperature, heated to 720 760, kept warm for 3 6 hours, and slowly cooled to about 600 with the furnace, and then air-cooled out of the furnace. It is softened annealing stress relief annealing 600-650, holding for 1-3 hours.

The purpose of graphite iron annealing is to decompose the cementite in cast iron into graphite and ferrite. In the production of ductile iron, graphitization annealing heat treatment is commonly used to obtain high-toughness and attitude modification ferrite clear sail cast iron.

Does heat-resistant ductile iron need heat treatment, heat treatment of ductile iron.

The fragmentation effect of spheroidal graphite on the matrix is small, so the mechanical properties of ductile iron mainly depend on the matrix structure, so the mechanical properties of ductile iron can be significantly improved by heat treatment.

Anneal. Stress relief annealing The casting residual stress of ductile iron is about twice as great as that of gray cast iron. For ductile iron castings that no longer enter the base and undergo other heat treatments, they must be annealed for stress relief.

The purpose of graphitization annealing is to decompose the free cementite in the as-cast structure and the eutectic cementite in the pearlite, obtain ductile iron with high plasticity ferrite matrix, eliminate casting stress, and improve its processability.

Normalizing. The purpose of normalizing is to obtain a matrix structure dominated by pearlite, refine the grains, and improve the strength, hardness and wear resistance of ductile iron. Normalizing can be divided into two types: high-temperature and low-temperature normalizing.

For high-temperature normalizing of thick-walled castings, air cooling or even spray cooling should be used to ensure the acquisition of pearlite ductile iron.

Low-temperature normalizing is to heat the casting to 840 860, keep it warm for 1 4h, and empty the furnace to obtain ductile iron with pearlite + ferrite matrix.

The thermal conductivity of ductile iron is poor, and the internal stress of the casting after normalizing is large, therefore, a stress-relieving annealing should be carried out after normalizing.

Yes, heat-resistant ductile iron needs heat treatment because its microstructure and properties are affected by heat treatment. Heat treatment can improve the microstructure of castings, improve the mechanical properties of castings, improve the corrosion resistance of castings, improve the thermal stability of castings, and improve the surface quality of castings. Therefore, heat-resistant ductile iron must be heat treated for better performance.

Quenching, annealing, tempering and heat recovery treatment of ductile iron in heat treatment furnaces.

In order to improve the overall performance of iron castings, there are often nodular iron annealing to eliminate white mouth annealing, annealing to improve toughness, normalizing and quenching to improve the strength of ductile iron.

1.Quenching and tempering of ductile iron.

Ductile castings require higher hardness as bearings, and iron castings are often quenched and tempered at low temperatures. The process is: the casting is heated to a temperature of 860-900, the original matrix is austenitized and then cooled in oil or molten salt to achieve quenching, and then heated and tempered by 250-350, the original matrix is converted into tempered martensite and residual austenite structure, and the original spherical graphite form remains unchanged.

The treated castings have high hardness and certain toughness, retain the lubricating properties of graphite, and improve the wear resistance.

As shaft parts, such as the crankshaft and connecting rod of diesel engine, ductile iron castings require comprehensive mechanical properties with high strength and good toughness, and quenching and tempering iron castings are carried out. The process is: the iron castings are heated to a temperature of 860-900 to keep warm to austenitize the matrix, and then cooled in oil or molten salt to achieve quenching, and then tempered at a high temperature of 500-600 to obtain the tempered sostenite structure (generally there is still a small amount of pure ferrite), and the original spherical graphite form remains unchanged.

After treatment, the strength and toughness are well matched, and it is suitable for the working conditions of shaft parts.

2.Annealing of ductile iron to improve toughness.

In order to improve the ductility or toughness of the casting, the iron castings are often reheated to 900-950 and kept warm enough time for high-temperature annealing, and then the furnace is cooled to 600 and cooled to 600. In the process, the cementite in the matrix decomposes graphite, and graphite is precipitated from the austenite, which is concentrated around the original spherical graphite, and the matrix is fully converted to ferrite.

If the as-cast structure is composed of (ferrite pearlite) matrix and spherical graphite, in order to improve toughness, only the cementite in the pearlite needs to be decomposed into ferrite and spheroidal graphite, and the iron castings are reheated to a eutectic temperature of 700-760 up and down after heat preservation and cooled to 600 after furnace cooling.

3.Normalizing to increase the strength of ductile iron.

The purpose of ductile iron normalizing is to convert the matrix structure into a fine pearlite structure. The process is to reheat the ductile iron castings with ferrite and pearlite as the matrix to 850-900 temperature, the original ferrite and pearlite are converted into austenite, and part of the spherical graphite is dissolved in austenite, and the air-cooled austenite is transformed into fine pearlite after heat preservation, so the strength of the ductile casting is improved.

The purpose of ductile iron annealing is different, and the process method is also different, so it is recommended that you check the relevant content in the first volume of the heat treatment manual as needed.

It can be either surface hardened or solid hardened.

Ductile iron can be quenched in one piece, which is a property different from gray cast iron.

Summary. Hello, thank you for your inquiry, about your questions, the answer is as follows: Yes, ductile iron can be produced by hot chamber die casting.

Hot chamber die casting is a commonly used metal die casting process for low-melting alloys, such as zinc and magnesium alloys, as well as high-melting alloys such as ductile iron. In the hot chamber die casting process, the metal alloy is heated to a liquid state and injected into a pre-prepared mold by pressure. This method has high production efficiency, good surface quality and high dimensional accuracy.

However, due to the high melting point of ductile iron, hot chamber die casting is often achieved using high-temperature and high-pressure equipment. It should be noted that hot chamber die casting has higher requirements for mold materials and equipment, because ductile iron has a high melting point and high liquid viscosity. Therefore, before performing hot chamber die casting ductile iron, it is necessary to ensure that the molds and equipment can withstand the requirements of high temperature and high pressure, and to optimize and control the process accordingly.

Hello, thank you for your inquiry, about your questions, the answer is as follows: Yes, ductile iron can be produced by hot chamber die casting. Hot chamber die casting is a commonly used metal rubber casting process for low melting point alloys, such as zinc alloys and magnesium alloys, as well as high melting point alloys such as ductile iron.

In the hot chamber die casting process, the metal alloy is heated to a liquid state and injected into a pre-prepared mold by pressure. This method has high production efficiency, good surface quality and high dimensional accuracy. However, due to the high melting point of ductile iron, hot chamber die casting is often achieved using high-temperature and high-pressure equipment.

It should be noted that hot chamber die casting has higher requirements for mold materials and equipment, because ductile iron has a high melting point and high liquid viscosity. Therefore, before performing hot chamber die casting ductile iron, it is necessary to ensure that the molds and equipment can withstand the requirements of high temperature and high pressure, and carry out the corresponding process optimization and control. 殺

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Pro-ductile casting Shengwu orange iron hard heat treatment: generally using the method of vacuum tempering, vacuum surface tempering can make the material have higher strength and higher toughness, especially at high temperature, can effectively improve the microstructure of metal materials, so that the life of parts is longer. Precautions for tempering include:

1. Choose the right tempering temperature, which is generally low temperature and low cooling; 2. Use patches with good quality orange mess to avoid defects when baking materials; 3. Evenly disperse the material in the vacuum furnace for uniform tempering. In addition, it is also necessary to control the composition of the alloy to make the properties of the alloy meet the requirements.