Silicon can be added to steel to prevent blistering during manufacturing.
Dead steel is a form of steel that has been treated to be completely deoxidized when it is processed during the casting stage. The deoxidization of the steel ensures a more uniform consistency in the finished product, increasing density and durability. There are a number of applications for dead steel and certain types of steel must be dead to meet material standards. Material testing can be used to determine whether or not steel has deoxidized if there is any question about the integrity of a steel product.
Stainless steels are almost always dead steels.
When steel is heated for casting, it interacts with oxygen in the air. Normally, some oxygen dissolves in the molten steel and travels with it to the mold. Some of the oxygen bubbles out as the steel sits in the mold, but some is trapped, where it interacts with the carbon in the steel to create carbon monoxide.
Carbon monoxide, in turn, creates tiny bubbles within the finished product. These bubbles compromise the integrity of the steel, creating weak points that can break or fracture, especially under stress. The bubbles also alter the texture of the steel and make it less dense. In some cases, this may not be seen as a problem, but in others, it can become a problem. The steel used in the manufacture of a bridge, for example, must be able to withstand stresses without developing cracks.
When making dead steel, a material such as aluminum, silicon, or manganese is added to it before it is poured into molds. This deoxidizes the steel, forcing oxygen out of the steel, so that by the time it reaches the mold, most, if not all, of the oxygen is gone. Some people say “dead” is a reference to the fact that the steel doesn’t bubble up in the mold after it’s poured.
Dead steel has a very uniform grain and texture as a result of the absence of carbon monoxide bubbles. It is also very dense and lacks the small holes found in steel that has not been killed, making it heavier than steel pieces of the same size that have not been killed. Broken steel is sometimes subject to shrinkage due to density, which can be a problem in certain foundry applications. The strength and durability of this steel product is enhanced by deoxidation, although factors can influence the qualities of a finished steel product.