Stainless steel is a very resourceful metal. We can see the use of SS (stainless steel) for CNC (Computer Numerical Control) Machining and CNC turning in;
- The aerospace industry
- Automotive industry
- And marine industries
Stainless steel is famous due to its corrosion resistance. Moreover, various alloys and grades of stainless steel are available. There is a wide range of applications and use cases. In this article, I will explain the various types of stainless steel.
Moreover, I will also explain the mechanical properties of stainless steel (SS). And I am hopeful that it will help you to determine the top grade for your project. Yet, you can visit https://www.prime99.com to learn about the link between SS and CNC machining.
General categories of stainless steel (SS):
There are five general categories of stainless steel (SS) available. They are available with different alloying basics and material structures:
- Austenitic Stainless Steel
- Ferritic Stainless Steel
- Precipitation Hardened Steel
- Martensitic Stainless Steel
- Duplex Stainless Steel (austenitic-ferritic)
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Austenitic stainless steel:
The primary use of austenitic stainless steel is for some specific products. The products that need strong corrosion resistance use this steel. Industrial and Domestic architectural products use austenitic stainless steel in general. These could include;
- Nuts and bolts and other fasteners
- Industrial Gas Turbines
- Food processing equipment
The fame of austenitic stainless steel is its machinability and weldability. It means manufacturing companies often use them for CNC machining. This is not possible to hard austenitic stainless steel by heat. It is due to its most of crystalline. And that specific thing makes these steels non-magnetic.
Popular grades of this steel include 304 and 316. And have between 16 and 26 percent chromium.
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Ferritic steel:
Ferritic stainless steel (SS) includes around 12% chromium. Due to its chemical composition, it differs from other stainless steel (SS) types. Another thing that differentiates it from other steel is the molecular grain structure.
Due to its body-centered cubic grain formation, ferritic steel is magnetic. That’s why it is different from austenitic steel. With lower corrosion resistance and heat-resistance than other steel, its uses are different. So, the following are some of the general uses of ferritic steel;
- For automotive parts
- For kitchen appliances
When it comes to stress corrosion cracking, ferritic steel presents high degree resistance. Due to this, it is a popular preference of steel for environments where chloride may be available. If exposed to a corrosive atmosphere, stress corrosion cracking can degrade steel. It happens most of time when exposed to chlorides.
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Martensitic stainless steel and its uses:
We can perform heat-treatment and process of hardness on martensite steel. As it is a tough form of steel, it makes it different from other steel. Yet, the chemical resistance ability is minimal compared to austenitic steels.
Martensitic steel offers a low cost, which is a clear benefit of it. Also, it is air-hardening metal with good corrosion resistance. Due to this, martensitic steel is easy to form, with the least chromium content of 10.5%. Following are some of the uses of martensitic steel;
- Cutlery
- Car parts
- Surgical Instruments
- Steam, gas, and jet turbine blades
- Valves
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Precipitation Hardened Steel:
Precipitation-hardened steel differs from others because of its most robust steel grade. Precipitation hardened steel is heat treatable and has excellent corrosion resistance. The most famous grades of precipitation-hardened (PH) steels are;
- 17-4 PH
- And 15-5 PH
Due to these excellent properties, its uses are as follows;
- To make aerospace components on a large scale.
- Its other ample use we can where extreme durability and reliability are essential
- Oil, gas, and nuclear industries also use precipitation-hardened steel (PH). The reason is that it offers great things. It provides combination of high strength and lower but workable degree of toughness.
- For making knives
- Firearms
- Surgical Instruments manufacturing industries also use this steel.
- Hand Tools
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Duplex Stainless Steel:
Duplex stainless steel, in some areas, its second name is austenitic-ferritic stainless steel. This stainless steel has a two-phase metallurgical structure. Duplex stainless steel includes both ferritic and austenitic phases. The duplex stainless steel has a higher strength than other austenitic stainless steel. This type of stainless steel also has extra corrosion resistance.
A low quantity of molybdenum and nickel content exists in duplex steel. Due to this, duplex steel costs are less compared with austenitic grades. Thus, heavy industrial applications such as the petrochemical industry use duplex alloys.
Factors to consider while the selection of stainless steel grade for CNC machining:
We need to consider many factors when choosing a material for any project. While CNC machining tube bearing, you have to select suitable material. As many different stainless steel grades are available in the market. So, it will be a challenge for you to narrow down your choice. Yet, I will recommend you to follow some factors for the right selection. Thus, you should be in a situation to determine which grade is right for you.
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Strength:
Tensile strength is a significant factor in choosing best material for your project. I will recommend understanding the forces and loads that will experience the parts. Also, compare this against the different tensile strengths on offer. It will help you remove any materials that do not offer the strength you need.
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Heat treatment:
If you need specific hardness for your parts, you may wish to think of heat treatment. Heat treatment improves the hardness of your components. But, this process will also increase your actual cost. Also, note that you cannot perform heat treatment process on austenitic stainless steels. Thus, you will not choose the same and remove it from your material choice category.
The other factors are as follow;
- Magnetism
- Cost
- And the availability of grade
