What Is The Material Of The Engine Valve?

Especially the exhaust valve?
The material of engine valve is generally austenitic.
The exhaust valve consists of three parts of materials:
1、 The big end is 21-4N austenitic material, which is treated by solution aging. The grain size is 6-9, the hardness is above 30HRC, and it can work at 850 ℃ for a long time.
2、 Cobalt base alloy STELLITEF is hardfacing on the working surface of the head cone, which has strong wear resistance, corrosion resistance, impact resistance and high creep strength under high temperature, and is crucial to the service life of the valve.
3、 The small head end is quenched with a hardness of 50HRCmin, which effectively improves the impact pitting resistance of the small head end. As the lock clamping groove is a three groove structure, it is quenched through the groove to deal with the spinning problem during operation. The hardness is above 600HV, ensuring the wear resistance of the valve stem and improving the service life of the valve.