Core Principle

A choice between "high strength/hardness" and "low cost/easy machinability."

1018 (Low Carbon Steel)

• Inexpensive, soft, easy to machine and weld
• Low strength, cannot be significantly hardened
• Best for: brackets, base plates, non-wearing applications

4140 (Alloy Steel)

• Much stronger and tougher than 1018
• Can be heat-treated for high hardness and wear resistance
• Higher material and machining costs
• Best for: shafts, gears, high-load bolts

Selection Guide:
• Choose 1018 for low-stress, non-wearing applications
• Choose 4140 for high-strength, wear-resistant parts
• Specify heat treatment requirements for 4140