Seen an exhaust and want to buy one? But you don't know whether to get a less expensive mild steel or a stainless steel...
In this article, I will be explaining the different types of materials used in exhausts, and the pros and cons of the different materials.
Mild steel is the most prevalent kind of steel, and it is made up of iron and a small amount of carbon. It's easy and affordable to manufacture an exhaust system with mild steel. However, it can rust easily and is built thicker and heavier.
Inexpensive to buy
Cheap and easy to manufacture
Mild steel exhausts are easy and cheap to manufacture and therefore lead to affordable prices, especially on the used market.
Rusts easily and quickly
Thick and heavy construction
The main disadvantage of mild steel exhausts is corrosion. Some exhaust systems are untreated, and as a result, they rust quickly.
Although some exhaust are zinc coated or hot dipped in aluminium which helps prevent corrosion, a mild steel exhaust will simply be more exposed to the climate and will rust.
Also, the pipes are often built thicker, which helps prevent them from succumbing to rust too soon but also adds weight.
Stainless steel exhaust are ideal since they don't rust. It's a corrosion-resistant alloy metal manufactured from iron and 10-20% chromium. However, they're more expensive.
There are many grades of stainless steel, but grade 409 is the most common.
Strong and durable
Pliable and reasonably inexpensive to manufacture
Rusts much less than mild steel exhaust
Usually lighter than mild steel
It's still highly strong and pliable, making it perfect for a variety of applications, including cutlery, structures and buildings, and is used widely in exhaust systems.
Exhaust systems made of stainless steel can last far longer and are often lighter than their mild steel counterparts.
The main drawback of a stainless steel exhaust is a higher price. Still, a stainless steel exhaust is fairly priced and is usually worth the additional cost.
Titanium exhaust systems contain almost entirely titanium. These exhaust are much lighter, just as durable as stainless steel, and turn blue when heated, but they are very expensive.
Just as durable as steel
Turns blue when heated
These systems will often be about 40% lighter while maintaining the same strength. Titanium alloys also become blue when heated, which does look great.
Titanium exhausts aren't more complex to make than steel exhausts. In many cases, the same machinery and methods that are used to make stainless systems may be used.
The disadvantage to titanium exhausts is the cost, they are very expensive. Titanium exhausts are usually limited to the most exotic cars.
Inconel is an alloy comprised mostly of nickel and chromium. It's popular in the aerospace and nuclear energy sector due to its strength and high melting point.
For years, F1 vehicle exhausts have been manufactured of Inconel 625, partially because the material allows for incredibly thin and light weight construction, and also because of its excellent heat resistance.
However, it's the F1 application that should alert you to Inconel's drawbacks. It's a costly material to make and a tough metal to deal with, making creating an exhaust from Inconel is expensive and difficult.
It's mostly unused on street cars as a result.