Heat Resistant Stainless Steel Castings

What are heat-resistant stainless steel castings?

Heat-resistant means the part can be used in high-temperature applications without damage to itself or other parts. It’s usually specified as being able to withstand temperatures up to 500°C (932°F). The term “stainless” refers to the fact that the material does not rust when exposed to air at room temperature.
Heat-resistant stainless steel castings are steels that work at high temperatures. The development of heat-resistant steel castings is closely related to technological advances in various industrial sectors such as power stations, boilers, gas turbines, internal combustion engines, and aero engines. Due to the different temperatures and stresses of the various types of machines and installations, and the environment in which they are used, the types of steel used vary.
The most common materials for making heat-resistant steel castings include austenitic stainless steel, ferritic stainless steel, and martensitic stainless steel. These alloys have been developed over time with the aim of improving their resistance to corrosion and wear.
In this article, we will discuss the properties of these three types of stainless steel and how they can be applied in the manufacturing process of heat-resistant steel castings.

Heat-resistant stainless steel casting classification

Classified by alloying element content

1) Low carbon steel: In the middle of such steel, it contains or rarely contains other alloying elements, and its carbon content generally does not exceed 0.2%.
2) Low-alloy heat-resistant steel: In this type of steel, one or several alloying elements are contained, but the content is not high. The total amount of alloying elements contained in the steel is not more than 5%, and the carbon content is not more than 0.2%.
3) High-alloy heat-resistant steel: In this type of steel, there are many alloying elements, and the content of alloying elements is generally above 10%, even as high as 30% or more.

Classified by steel characteristics

1) Anti-oxidation steel (or heat-resistant steel): This type of steel has good oxidation resistance and high-temperature corrosion resistance at high temperatures (generally 550 ~ 1200 ° C), and has a certain high-temperature strength. It is used to manufacture various types of heating furnace parts and heat exchangers, to manufacture the combustion city of hot steam turbines, boiler squash, heating furnace floor, and roller table, and furnace tube. Antioxidant performance is the main indicator and the parts themselves are not subject to great stress.
2) Heat-strength steel: It can withstand considerable additional stress at high temperatures (usually 450-900 °C) and has excellent resistance to oxidation and high-temperature gas corrosion. It is usually required to withstand cyclic variable stress. It is commonly used as the rotor and blade of steam turbines, gas turbines, superheaters of boilers, bolts, and springs working at high temperatures, intake and exhaust valves of internal combustion engines, petroleum hydrogenation reactors, etc.

Classified by the main purpose

Heat-resistant steel for industrial furnaces: in addition to reactors, power station boilers, petrochemical industrial furnaces, in metallurgy, machinery, building materials, light industry, etc., widely used in heat exchangers, heating furnace tubes, reflecting tanks, etc. A variety of heat-resistant parts, in addition to the use of heat-resistant steel deformation of plates, tubes, rods, etc., and the use of a large number of heat-resistant steel castings. Various annealing furnace covers of metallurgical plants, muffle cans, radiant tubes, charging frames, chain belts, etc. of controlled atmosphere continuous heating furnaces, etc., mostly adopt 310 (0Cr25Ni20) or 3Cr24Ni7SiNRe, 2Cr25Ni13 steel and the like. In the continuous heating furnace and heat treatment furnace of the metallurgical plant, a large number of furnace bottom rolls and radiant tubes are also made of high alloy heat-resistant steel centrifugal casting tubes.

Heat-Resistant Stainless Steel Castings Grade

The heat-resistant casting commonly used stainless steel grades are 0Cr18Ni9, 00Cr18Ni9, 1Cr18Ni9Ti, 0Cr17Ni12Mo2, 00Cr17Ni12Mo2, 3Cr24Ni7SiNRe, 0Cr23Ni13, 1Cr20Ni14, Cr25Ni20Si2. , 00Cr10Ni20Mo6Cu6, 4Cr25Ni35NbW, 70CrMoVBRe, 4Cr28Ni48W5Si2, 3Cr26Ni4MnMoRe, and the like.

In the cement industry, heat-resistant steel chains in the pre-tropical zone of wet-process cement kilns, tweezers used in large-scale cement kilns, and material buckets for cooling machines, etc., use a large number of heat-resistant steel parts, such as 3Cr24Ni7SiNRe. , 1Cr20Ni14, Cr25Ni20Si2, and so on.

Heat Resistant Steel Casting Manufacturing Processes

There are many ways to manufacture heat-resistant steel castings including direct chill casting, semi-indirect chill casting, die casting, sand mold casting, and investment casting. Each method has its own advantages and disadvantages. In this section, we will look at each of these processes and explain what benefits and drawbacks they have.

Direct Chill Casting

This is the simplest way to make heat-resistant steel castings and involves pouring molten metal into a mold that contains cold water. The cooling rate is controlled by the amount of water in the mold. Direct chill casting allows you to produce large quantities of castings quickly and cheaply. However, it requires a lot of maintenance to keep the mould clean and free of defects. It is therefore not recommended for small batches or prototypes.

Semi-Indirect Chilling

This process uses an intermediate layer of chilled water to control the temperature of the molten metal during solidification. Semi-indirect chilling allows you to produce smaller quantities of castings faster than direct chill casting. It is also easier to maintain since the mould does not need to be cleaned after every casting. However, it can only be used with certain types of metals. For example, aluminum cannot be used with semi-indirect chilling due to the risk of cracking caused by thermal shock.

Die Casting

Die casting is one of the most popular methods of manufacturing heat-resistant steel castings. It involves forcing molten metal through a die which creates a cavity inside the casting. The shape of the die determines the final shape of the casting. Die casting produces castings of uniform quality and is ideal for producing small quantities of parts. It is also easy to automate so it is often used for mass production. However, it is expensive and time-consuming.

Sand Mold Casting

Sand mold casting is similar to die casting except instead of using a die, the molten metal is poured into a mould made from sand. This type of casting is suitable for making large quantities of castings as it is quick and cheap. However, it is difficult to get perfect results as there is no way to check the internal structure of the casting before removing it from the mould.

Investment Casting

This is the most common method of manufacturing heat resistant steel casting. Investment casting involves filling a ceramic shell with molten metal and then allowing it to cool slowly. Once the metal has cooled down sufficiently, the ceramic shell is removed leaving behind a hollow casting. Investment casting is suitable for producing small quantities of castings as well as larger ones. It is also relatively inexpensive and quick. However, it is more complex than other casting techniques and requires skilled technicians to operate correctly.

How to Make Heat-Resistant Steel Castings:

Heat-resistant steel castings are manufactured using any one of the above casting techniques. They are usually produced in small batches but may be produced in large quantities depending on your requirements. To ensure that your castings meet all required specifications, it is important to follow the correct procedures when manufacturing them. Below are some tips on how to make heat-resistant steel casting.

1. Choose the Right Metal

The first step in manufacturing heat-resistant steel cast is choosing the right metal. There are two main categories of heat-resistant steel: austenitic and ferritic. Austenitic heat-resistant steels contain nickel and chromium whereas ferritic heat-resistant steels do not. Ferritic heat-resistant steels are cheaper than austenitic heat-resistant steel but they tend to have lower strength. If you want to use ferritic heat-resistant steel, you will need to add extra elements such as molybdenum or tungsten to increase its strength.

2. Select the Correct Moulding Process

The second step in manufacturing heat-resistant steels is selecting the correct moulding process. You should choose between semi-direct chill (SDC) and indirect chill (IC). SDC is used for producing small quantities of heat-resistant steel castings while IC is used for producing large quantities of castings. Both processes involve pouring molten metal into a mould where it solidifies. In SDC, the mould is placed directly over an ice bath while in IC, the mould is placed in a water tank. When the metal reaches room temperature, the moulds are removed leaving behind hollow castings.

3. Use Proper Tools

The third step in manufacturing heat-resistant castings is using proper tools. A good set of tools can save you a lot of money and time. For example, if you are going to produce a batch of 100 castings, you will need at least 10 sets of dies. Each set consists of a plunger, a core pin, a core plate, a sprue bush and a runner bush. These tools must be cleaned regularly to prevent contamination. Also, keep in mind that different types of metals require different tools. For instance, aluminum needs to be handled carefully because it reacts easily with air.

4. Follow the Correct Procedures

The fourth step in manufacturing heat-resistant casting is following the correct procedures. This includes cleaning the tools properly before each casting cycle and storing them safely after use. Cleaning the tools is very important because dirt particles can contaminate the metal during casting. Storing the tools safely ensures that they remain clean and ready for use next time.

5. Ensure Quality Control

The fifth step in manufacturing heat-resistant iron castings is ensuring quality control. This means checking every aspect of the casting process from start to finish. Checking the castings after production is also important. Inspect them thoroughly to ensure that there are no defects.

Heat-Resistant Stainless Steel Castings Parts

As the heat-resistant stainless steel casting pipe & tube manufacturing company, able hardware supply these casting pipes & tubes for industrial and automotive below:

If you need any heat-resistant casting products, ask the able hardware to make a quotation for you.

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