Alloy steel casting is the steel casting process that is alloyed with numerous elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low-alloy steels and high-alloy steels. Most commonly, alloy steels used in investment casting are low-alloy steels.
Strictly speaking, every steel is an alloy, but not all steels are called “alloy steels”. The simplest steels are iron (Fe) alloyed with carbon (C) (about 0.1% to 1%, depending on type). However, the term “alloy steel” is the standard term referring to steels with other alloying elements added deliberately in addition to the carbon. Common alloyants include manganese (the most common one), nickel, chromium, molybdenum, vanadium, silicon, and boron. Less common alloyants include aluminum, cobalt, copper, cerium, niobium, titanium, tungsten, tin, zinc, lead, and zirconium.
With investment castings made in alloy steel, we can achieve lots of properties including (as compared to carbon steels): Strength, hardness, toughness, wear resistance, corrosion resistance, and hardenability. Of course, heat treatment will help to improve some of these improved properties if casting can not meet directly.