Aluminum rivets are often used to secure steel material, but that doesn’t mean it’s the best practice. In this article, you will learn whether aluminum rivets can be used in steel, steel rivets versus aluminum, and the strength of aluminum rivets.
Aluminum Rivets in Steel: Do They Work?
Aluminum rivets are an ideal lightweight yet secure way of fixing multiple materials, perfect for aluminum sheets.
When large steel pieces are linked via aluminum rivets or other aluminum-based material, rust builds and damages the rivets, causing the parts to fall free. This effect, known as galvanic corrosion, occurs when the aluminum and steel material is subjected to an electrolyte. Electrolytes take the form of liquid water or humidity.
In the mildest scenario, discoloration occurs when stainless steel combines with aluminum. This is also known as ‘tea staining.’
Corrosion and discoloration can be avoided by using insulation and performing routine visual inspections for any contact points. Passivation can also generate a passive layer on the fastener for improved corrosion resistance. However, it’s generally best to avoid using aluminum rivets to secure steel surfaces.
Preventing Corrosion in Rivets
The most popular way to avoid galvanic corrosion is to choose metals close in the galvanic series. The likelihood of degradation reduces by separating the incompatible metals. Stainless steel that comes into contact with materials like copper is less likely to cause galvanic corrosion than stainless steel that comes in contact with aluminum.
Although aluminum reacts unfavorably with stainless steel, depending on local environmental circumstances, considerable surface areas of aluminum to stainless steel can be acceptable. In a marine environment, severe corrosion is likely to occur. However, to mitigate this effect, specific strategies can use. Using an isolating coating or paint on the aluminum and steel to electrically isolate them is an excellent approach to decrease corrosion. Separating the two dissimilar materials with insulating washers creates a safe surface area.
Sandwiching an intermediate material between an aluminum rivet and steel plate reduces the likelihood of corrosion. Washers or gaskets made of plastic or rubber provide a decent option. However, engineers should carefully consider the effects of the environment on long-term reliability.
Steel Rivets vs. Aluminum Rivets
|Aluminum||Lightweight, corrosion-resistant, durable||Aircraft, Automotive, Air conditioning systems|
|Stainless Steel||Strong, hard, corrosion-resistant, and withstands wear||Aircraft, Automotive, Rail transport|
Aluminum rivets are the lightest of all types and have the best corrosion resistance but the lowest tensile and shear strengths. Steel rivets outperform aluminum rivets in tensile and shear strength, are less expensive than stainless rivets, and are more minor corrosion resistant than aluminum or stainless. Stainless fasteners are corrosion-resistant and have the best shear and tensile strengths.
Aluminum Rivets Strength
Rivets provide anywhere from a hundred pounds to over a thousand pounds of shear resistance. Specific values depend on the material and diameter of the subject rivet.
|Configuration||Shear Strength (min) by Diameter (“)||Tensile Strength by Diameter (“)|
|Aluminum Rivet/Steel Body||1/8: 170 lbs.; 5/32: 260 lbs.; 3/16: 380 lbs||1/8: 220 lbs.; 5/32: 350 lbs.; 3/16: 500 lbs|
|Steel Rivet/Steel Body||1/8: 260 lbs.; 5/32: 370 lbs.; 3/16:540 lbs.||1/8: 310 lbs.; 5/32: 470 lbs.; 3/16: 680 lbs.|
|Stainless Rivet/Steel Body||1/8: 420 lbs.; 5/32: 650 lbs.; 3/16: 950 lbs.||1/8: 530 lbs.; 5/32: 820 lbs.; 3/16 1200 lbs.|
For permanent fastener applications, aluminum rivets provide a great choice. Solid aluminum rivets have several advantages, such as:
- Corrosion resistance: A protective oxide layer forms naturally on the aluminum and its alloys’ surface. In fact, this oxide layer protects the material from elements and corrosion.
- High strength-to-weight ratio: Of all the metals, aluminum has the best strength-to-weight ratio. It is as robust as steel in most applications but weighs roughly one-third.
- Aluminum solid rivets are nonmagnetic and nonsparking, making them suitable for use in potentially explosive environments such as electronics and associated applications.
- Aluminum possesses excellent thermal and electrical conductivity. It has 59 percent of copper’s thermal and electrical conductivity yet only a third of the density.