Heat treatment process for diesel engine aluminium cylinder heads quenches the casting in concentrated liquid nitrate or chromate salts

摘要

In a heat treatment process for a cast aluminium automotive diesel engine cylinder head, the cast block is annealed and then cryogenically shock-quenched with water and liquid nitrogen. After cooling, the temperature of the cylinder head is suddenly raised by placing in concentrated liquid nitrate or chromate salts whose boiling point is above that of water at normal atmospheric pressure.