Alloy 455 is an alloy melted by several sources also known as Custom 455, the trademarked name of Carpenter Specialty Alloys. It is a martensitic age-hardenable stainless steel that offers a unique set of qualities. This alloy is double vacuum-melted using a Vacuum Induction Melt followed by a Vacuum Arc Remelt. It combines corrosion resistance, one-step age hardenability, ease of fabrication, and yield strength that is thrice the strength of standard stainless grade 304. The one-step aging treatment provides this material with very good high yield strength coupled with good ductility and toughness. Custom 455 should be considered when a combination of the following is needed: high strength, corrosion resistance, simplicity of heat treatment and/or ease of fabrication.