Car Buffs Trust Aircraft Quality 4340 Steel to Boost Performance and Efficiency
December 1, 2012 -
The aircraft quality AISI 4340 grade steel that helps to strengthen the landing gear and engine components of many commercial airliners deserves its excellent reputation. Its lightness and durability make it an ideal structural component in an industry that demands lightweight and flexible machines.
4340 alloy steel is also known as a principal component of the aftermarket gears and engine parts that power some of the fastest and most fuel-efficient cars on the road. This special type of metal can be found in high-performance clutch flywheels, axles and trailing arms. It is also used liberally in the harshest environment beneath the hood of a car: the engine block. Racing enthusiasts and off-road drivers rave about aftermarket pistons and crankshafts forged from 4340 grade steel.
Aircraft quality 4340 steel's unique properties make it a perfect fit for the top-of-the-line crankshafts that serious automotive buffs require. Compared to weaker and less durable grades of steel, it is especially receptive to heat and can be worked at either extremely hot or relatively cool temperatures.
This type of steel is forged at blistering hot temperatures of up to 1,200 degrees Celsius and can be annealed at temperatures of around 850 degrees Celsius. Annealing involves re-heating recently-forged steel and allowing it to cool as slowly as possible. This increases its malleability and allows it to be rolled into the tubes that comprise the "crank throws" of most crankshafts.
It also allows aircraft quality 4340 steel to be worked at cooler temperatures than many other types of steel. This is useful for pressing and stretching the material into the thin flywheels that connect to the crankshaft and harness its power. In fact, heat-resistant 4340 steel is the principal component of the engine blocks of many souped-up vehicles.
Even regular vehicles' crankshafts suffer tremendous abuse. In off-road and racing vehicles, crankshafts are subjected to many thousands of jarring piston impacts each minute. Automotive experts boast that crankshafts forged from 4340 steel can withstand cumulative impacts of up to 145,000 pounds per square inch. Even among high-quality grades of steel, such strength is unusual: Many formerly-favored varieties of automotive steel are rated to withstand impacts of just 90,000 pounds per square inch.
Due to its good strength to weight ratio, part size can be decreased while maintaining the required strength. This is yet another factor working in its favor of aircraft quality 4340: Engine blocks that incorporate significant amounts of 4340 grade steel tend to be lighter than standard blocks.
In fact, the 2013 Ford Fusion recently won Green Car Journal's Green Car of the Year Award thanks to its heavy reliance on this weight-reducing alloy. Whether it's helping engines last longer or ensuring that efficient cars can drive even farther on a single tank of gas, 4340 steel is a crucial component of high-performance engine blocks.