A2 is the most common grade of steel bar used to make tools for shaping metal, wood, and other materials. A2 medium-carbon chromium alloy steel is a member of the cold work tool steel group, designated by the American Iron and Steel Institute (AISI), which includes O1 low-carbon steel, A2 steel and D2 high-carbon high-chromium steel.
Cold work tool steel is a good choice for parts requiring a balance of wear resistance and toughness. They also work well for parts that need a minimum amount of shrinkage or distortion during the hardening process.
The wear resistance of A2 steel is intermediate between O1 and D2 steel, and it has relatively good machining and grinding properties. A2 is tougher than D2 steel, and has better dimensional control after heat treatment than O1 steel.
Altogether, A2 steel represents a good balance between cost and physical characteristics, and is often considered a general purpose, universal steel.
A2 steel is the most commonly used variety of the Group A steels listed in the ASTM A682 standard, which are designated “A” for air hardening.
During the heat treating process, the medium carbon content of about 1% allows A2 steel to develop full hardness through cooling in still air – which prevents the distortion and cracking that could be caused by water quenching.
The high chromium content (5%) of A2 steel, along with manganese and molybdenum, allows it to achieve full hardness of 57-62 HRC in thick sections (4 inches in diameter) – giving it good dimensional stability even for larger parts.
A2 steel bar is available in a several forms, including square, round, and rectangular. This highly versatile material can be used for a wide variety of tools that require wear resistance, such as industrial hammers, knives, slitters, punches, tool holders, and woodworking cutting tools.
For inserts and blades, A2 steel resists chipping so that it lasts longer, often making it a more economical choice than high-carbon D2 type steel.
It is often used for blanking and forming thread roller dies, stamping dies, trimming dies, injection mold dies, mandrels, molds, and spindles.