Classifying Alloy Steel

AISI numbering system example: 4140

• 41 = family of alloys
• 40 = nominal carbon content
• Expressed as a percentage – 40 = .40% carbon

Specifications

• ASTM
  • ASTM A-434 Class BC
  • ASTM A-295
  • ASTM A-322
• AMS
  • AMS 2301
  • AMS 6415
• Others

Trade names

• Etd 150
• Rycut 40
• Hardwear 40

Customer designation

• Caterpillar
• General Electric