Q: What Types of Metals Are Used to Make Exhaust Systems?

Chances are good that your exhaust system is made from 400-series steel. Cast iron is used for the exhaust manifold (stock). Aluminized steel is often used in aftermarket exhaust systems. In addition, a wide range of other metals can be added to the mix as alloys to provide greater strength or corrosion resistance depending on the type of exhaust in question.

Modern automotive exhaust system design, development, and manufacturing is mandated for the vehicle to be price competitive, application specific, and meet regulations. Material selection for the exhaust system plays a vital role due to the increased warranty requirements and regulatory compliances.

Exhaust system materials should possess high temperature oxidation resistance, thermo mechanical vibration resistance, external salt corrosion resistance and internal acid/base corrosion resistances.

The materials mostly used in exhaust systems are cast iron, stainless steel, mild steel / carbon steel. Recent trends towards light weight concepts, cost reduction and better performance, have led to the use of sheet metals. Nowadays, stainless steels are used in flexible bellows, catalytic converter, resonators, mufflers, pipes. Mild steel / carbon steel are used for flanges, pipes, and mufflers.

Stainless steel began as the material for decoration trims in automobiles. However, in recent years, it is mostly used as the material for exhaust systems. Exhaust system components have changed from conventional cast metals and aluminized carbon steel sheets to stainless steels, and from general-purpose stainless steels to specialty stainless steels of higher performance. This is due to stainless steels good performance and characteristics of high temperature, high corrosion resistance and appearance while meeting the modern needs for clean exhaust gases and reduced weight for better fuel economy.