CNC Machining: Which is Better, Aluminum Vs Stainless Steel?
Dec 01, 2022
Aluminum and stainless steel are the two materials we often use in CNC machining parts.
If you don't know the advantages and disadvantages of both of them, you can hardly evaluate the cost of processing, so today we will talk about aluminum and stainless steel in the processing of which is better.
Anodization is to aluminum what galvanization is to steel. The application of this outer, passive layer of thick oxide coating improves the resistance of aluminum to corrosion and abrasion. Although aluminum and stainless steel have some similarities, we will focus on how they differ. The conductivity and ferrousness of aluminum and steel are the first distinctions.
Non-ferrous materials, such as aluminum, lack magnetic properties, making them ideal for small electronics. When it comes to malleability, aluminum is usually the first thing that comes to mind. It can be easily bent, molded, and pressed into shape without requiring too much force. Steel is stronger, but aluminum can be hard-anodized to make it just as strong if needed or if there is no other choice.
When it comes to steel properties, you’ve probably heard of stainless steel. One steel alloy has properties that make it less likely to stain, but it is not completely corrosion-resistant. There is regular steel and mild steel, but we will focus on stainless steel in this article.
This is because stainless steel is the ‘improved’ version of steel, and it is frequently compared to aluminum on many scales. For example, different metals are frequently compared in terms of electrical conductivity, thermal conductivity, density, and other similar factors. Stainless steel, for example, is denser than aluminum, and the scale also demonstrates that stainless steel is a far better heat conductor than aluminum.
When you see the term “ferrous” next to stainless steel, it means that it contains (or is made of) iron. Most ferrous metals and alloys rust when exposed to the elements due to the high amounts of carbon used in their manufacture. Carbon steels are typically galvanized to increase corrosion resistance. Galvanized steel that doesn’t rust has a layer of zinc on the outside that becomes part of the steel’s chemical makeup.
Types of Stainless Steel
Stainless steel is classified into three types. These are the following:
Austenitic stainless steel
Austenitic stainless steels are nonmagnetic stainless steels with high levels of chromium (16–26 percent) and nickel (6–12 percent). They also have low carbon levels. These alloys give austenitic steel high formability and corrosion resistance. As a result, these stainless steels are the most commonly used. 304 and 316 stainless steel are two common types of austenitic steel.
304 Stainless Steel: It is impossible to tell which materials are made of 304 or 316 stainless steel with the naked eye. Their chemical composition, properties, and applications, however, differ. For example, 304 steel is an austenitic alloy composed of 18% chromium and 8% nickel. As a result, 304 steel is resistant to oxidation and corrosion and has increased durability. 304 stainless steel is commonly used in automotive molding and trim, electrical enclosures, wheel covers, stainless steel cookware, storage tanks, and piping, among other things. Simply put, 304 steel is the least expensive corrosion-resistant option.
316 Stainless Steel: 316 stainless steel is composed of 16% chromium, 10% nickel, and 2% molybdenum. The addition of molybdenum improves the steel’s corrosion resistance even more. At high temperatures, it fared much better against chemical corrodents such as seawater and brine solutions, as well as sulfuric acid solutions, iodides, and fatty acids. Molybdenum-containing steels are often used in medical equipment and in many offshore, marine, and washdown settings.
Ferritic stainless steel
Ferritic stainless steels have a high chromium concentration (typically 12.5% or 17%, but as much as 27%) and low carbon content. They are also free of nickel. As a result, ferritic steel is magnetic and cannot be heated. Even though it is brittle because of impact transition, it is easy to shape, resistant to corrosion, doesn’t crack under stress, and is ductile.
Ferritic steels have applications in the automotive and industrial industries, as well as certain stainless steel cookware, despite being less corrosion resistant than austenitic-grade steels and generally less expensive. Molybdenum, aluminum, and titanium are also present in some ferritic steels.
Martensitic stainless steel
Martensitic stainless steels: the least common type of stainless steel alloy, martensitic stainless steels are low in carbon content, containing between 0.2% and 1%, and their chromium content ranges between 10.5% and 18%. In general, no nickel is present, but small amounts are occasionally added to increase corrosion resistance and toughness. Some grades may also contain selenium or sulfur to improve machinability.
Because of its low chromium and alloying content, martensitic stainless steel is less expensive than other types of stainless steel. They are known, however, for their hardness, strength, and moderate corrosion resistance. Due to their metal-to-metal wear and abrasion resistance, martensitic stainless steels are often used in industrial blades, vehicle springs, staple guns, cutlery, cookware, springs, scissors, and some surgical and dental instruments.
Aluminum VS. Stainless Steel
Hard-anodized aluminum or stainless steel: which is better?
The simplest way to look at this is to compare which pots are better, aluminum or stainless steel. Hard-anodized aluminum pots are typically nonstick and resistant to rust. Stainless steel pots and pans may last a little longer and are easier to clean. Anodized aluminum has a distinct advantage over steel and regular aluminum in that it is a superior heat conductor. Aluminum vs. stainless steel cookware is a common source of concern for chefs and home cooks, so if you intend to spend a lot of time in the kitchen, you should research these differences.
Which is heavier: aluminum or stainless steel?
Steel density has been briefly mentioned. Indeed, one of the most significant differences between stainless steel and aluminum is density. In comparison to aluminum, stainless steel is much denser, making it much more difficult to scratch. In comparison, aluminum is two and a half times lighter than stainless steel.
Which is more durable: aluminum or stainless steel?
When it comes to strength, stainless steel vs aluminum is a no-brainer. Steel is much tougher, more difficult to bend or mold, and more impact-resistant. Aluminum, on the other hand, can be hard-anodized to make it much stronger than it would otherwise be. This process ensures the durability of aluminum. If you need strength while keeping component weight to a minimum, anodized aluminum is the way to go.
Which is safer: aluminum or stainless steel?
The context determines the answer to this question. Both are safe to use in construction, but the degree of safety varies depending on the application. Similarly, when it comes to cooking and cookware, both are used in the preparation of food, and neither is a bad choice. While steel is the “safest” material, aluminum and anodized aluminum are close behind.
Which is more expensive: aluminum or stainless steel?
Steel is more common and easy to obtain, and it can be easily recycled and resold, making it much more affordable than aluminum. Steel can be less expensive than aluminum, even after it has been processed, galvanized, chem-treated, and painted. Aluminum is more difficult to produce or find in scrap, so its price can be slightly higher.
Stainless steel vs aluminum:Elemental composition
The elemental composition of a material is critical to CNC machining projects, as the composition of the metal has a large impact on hardness, corrosion resistance, durability, and strength. Stainless steel is an iron alloy containing at least 10.5% chromium, and other elements include aluminum, silicon, sulfur, nickel, selenium, molybdenum, nitrogen, titanium, copper and niobium, accounting for about 0.03%-1%. The presence of chromium determines the excellent properties of stainless steel in terms of heat resistance and corrosion resistance. Other elements that aluminum contains include: aluminum, silicon, zinc, magnesium, manganese, copper, iron, titanium, chromium, zirconium, and more.
Composition of Major Stainless Steel Alloys
Composition of Major Aluminum Alloys
Aluminum is known for its rust resistance, light weight, and general corrosion resistance and strength.
Stainless steel has excellent corrosion resistance and tensile strength, and its weight is about three times that of aluminum.
Stainless steel has excellent heat resistance, while aluminum has excellent thermal conductivity, but aluminum cannot withstand high temperature applications due to its melting point.
The welding performance of stainless steel is better than that of aluminum.
Aluminum is the first choice for lightweight conductive material, which achieves a good balance between conductivity and cost.
Aluminum is more suitable for die casting or extrusion, while austenitic stainless steel also has good formability and does not require additional processing.
The cost of stainless steel and aluminum fluctuates greatly according to different models. Usually CNC machining stainless steel is more expensive than aluminum.