Which is better, engine valve stem steel or bearing steel?

Engine valve stem steel is better than bearing steel; Bearing steel is used to manufacture balls, rollers and bearing rings. Bearing steel has high and uniform hardness, wear resistance and high elastic limit. Bearing steel has strict requirements on the uniformity of chemical composition, the content and distribution of nonmetallic inclusions and the distribution of carbides, and is one of the most stringent steel grades in all steel production. 1976 ISO, the international organization for standardization, has brought some commonly used bearing steels into international standards, and classified bearing steels into four categories: fully hardened bearing steels, surface hardened bearing steels, stainless steel bearing steels and high-temperature bearing steels.