Description
The steel for valve spring has been improved to meet stringent customers requirements. The new ladle refining technology made it possible that the composition of inclusions is CaO-Al -SiO eutectic in molten steel and is kept unchanged through solidification by continuous casting, in which molten steel does not contact with air. The inclusions show low melting temperatures and are easily deformed to elongated fine morphology in hot working from cast bloom to wire rod. In addition, as their hardness is reduced drastically down to as hard as steel, they are also deformed in cold drawing to finer ones. As a result, the steel shows no inclusions in optical inspections.
