Which material is commonly used for intake valves due to their exposure to lower temperatures?

Intake valves are commonly exposed to lower temperatures compared to exhaust valves, and low-alloy steels are often chosen for their balanced properties, including strength and resistance to wear under cooler operating conditions. These steels typically offer excellent machinability and can withstand the stress and fatigue associated with the opening and closing mechanisms of the engine.

Low-alloy steels can maintain flexibility and strength in cold temperatures, which is essential for an intake valve's longevity and performance. This makes them a suitable choice when a combination of mechanical strength and lower thermal output is desired.

While other materials like stainless steel and high-carbon steel can be used in valve construction, they may not provide the same advantages as low-alloy steels in terms of thermal performance under lower temperature conditions. Copper alloys, although beneficial for certain applications due to their thermal conductivity, do not possess the necessary strength and fatigue resistance needed for a reliable intake valve under normal operating conditions.