Applications of INCONEL 625 in the Automobile Industry

INCONEL 625 alloy was created in the early 1960s as a leader in nickel-based superalloys. It's tough, lightweight, versatile, and has excellent chemical and mechanical properties for a wide range of applications. No wonder it's been a favorite for nearly six decades.

625 alloy was originally developed for steam piping-a critical application that requires high strength, stability, and resistance to extreme temperatures. Since then, continued research and development have revealed and enhanced the alloy's range of properties. For example, it has a strong resistance to salt water, making it ideal for marine and offshore applications. Its excellent corrosion and pressure resistance also make it a material of choice for the automotive, nuclear, and chemical processing industries.

The automotive industry has a special need for lightweight, high-strength, and corrosion-resistant metals. In this article, we'll take a closer look at the properties of INCONEL 625 alloy and how to best use them in automotive manufacturing.

Elements of Excellence
INCONEL 625 alloy is a nickel-chromium-molybdenum alloy with small additions of iron and niobium. Nickel content is at least 58%, which is particularly beneficial for its excellent strength, toughness and corrosion resistance. Its corrosion resistance is further enhanced by the high chromium content of 20-23%. Chromium is extremely resistant to corrosion, especially in oxidizing media.

Molybdenum content is 8-10%, which enhances the alloy's strength and resistance to pitting and crevice corrosion. Molybdenum also enhances its corrosion resistance in non-oxidizing media. 5% iron further enhances the alloy's strength, while small amounts of niobium help prevent intergranular cracking after welding. The result is an alloy that is light, strong, easy to machine, and has excellent corrosion resistance in both oxidizing and non-oxidizing environments.

Strength and Durability
Due to the effects of molybdenum and niobium on the atomic matrix of 625 alloy, it can be strengthened without heat treatment. It can be used in the annealed state. 625 alloy has high overall strength and excellent tensile strength and corrosion fatigue strength. It is particularly resistant to chloride ion stress corrosion cracking.

Corrosion resistance is another outstanding quality of 625 alloy. It is widely used at sea and on ships as it is virtually immune to corrosion from seawater or freshwater. It also exhibits similar corrosion resistance to alkaline media and neutral salts.

This high temperature alloy can easily cope with even harsh extreme high temperature environments. It also performs well in low temperature corrosion conditions due to the addition of chromium and molybdenum.

Automotive Applications
The combination of power and performance, smaller displacement and lower emissions is at the heart of today's automotive industry. This places special demands on the metal components used in automotive manufacturing. Exhaust temperatures are higher than ever before, and the drive for sustainability means that vehicles need to last as long as possible. This means that each metal component needs to have the right combination of strength and resistance, depending on the specific function of that particular part in the car. Specific issues may include creep, wear, corrosion, low- or high-cycle fatigue, or extreme temperatures.

The special properties of INCONEL 625 alloy make it well suited for specific parts in automotive and other vehicle designs, including tailpipes, airbag rupture discs, isolation elements and oxygen sensors.

Tailpipes
Tailpipes have a particularly tough job. They are constantly exposed to corrosive and irritating substances such as rain and salt, so they must have excellent corrosion resistance. They can also be dented, scratched or hit by small objects such as stones. However, as the only visible part of the exhaust system, and an important feature of the car itself, they must look flawless.

INCONEL 625 alloy is highly valued for its resistance to salt and freshwater attack, its light weight, high strength, and corrosion resistance. It can also withstand high exhaust temperatures without failing.

Barrier Elements
Barrier elements are another important component of a car's exhaust system. They dampen vibrations, compensate for thermal expansion, and reduce potential wear. A strong, durable, and well-performing barrier element will extend the life of the entire exhaust system.

INCONEL 625 alloy's properties also make it an excellent choice. Because it remains stable at high temperatures and resists wet corrosion-a real risk given the winter exposure of exhaust pipes to road salt-barrier elements made from this alloy will perform well over the long term, extending the life of the exhaust system and saving time and money on repairs.

Oxygen Sensors
Also known as an oxygen sensor, an oxygen sensor is a part of the exhaust system that measures the amount of residual oxygen in the exhaust gases. Optimizing the air/fuel mixture allows the correct amount of fuel to be delivered to the engine cylinders, ensuring that the engine works properly and efficiently.

Oxygen sensors (modern cars are typically equipped with two) are also an important sustainability and safety measure. They are located on either side of the catalytic converter and monitor whether the catalytic converter is working properly and filtering harmful exhaust gases. Oxygen sensors are critical and need to have a long service life, even longer than the service life of the catalytic converter itself. 625 alloy is often used to make contact springs for oxygen sensors.

Airbag rupture discs
Thanks to huge advances in vehicle safety, airbags are now standard equipment in cars. Airbags save lives when they work properly, but can be very dangerous if they inflate at the wrong time. The mechanism of the airbag is controlled by a disc designed to rupture at a specific pressure, ensuring that the airbag is deployed exactly when needed.

625 alloy is the best choice for manufacturing these discs due to its resistance to extreme temperatures. This ensures that the airbag does not accidentally inflate in the event of a vehicle fire, avoiding injury to the driver, passengers and/or rescuers.

If you would like to know more about the application of 625 alloy in the automotive industry and other fields, please contact us. Our team will be happy to advise you.