4150 is a chromium-molybdenum alloy steel that is used in the quench and temper process to provide 4150 with its high strength and toughness. 4150 has a carbon content of .28-.33%, manganese at 0.70-0.85%, phosphorus at 0.035%. 4150 also contains sulfur, which 4130 does not contain. 4150 is used for applications that need a high strength and low weight such as in aircraft parts, gears and shafts. 4150 has greater toughness than 4130 so it can be used to make parts that require a higher level of toughness. 4150 is also corrosion resistant compared to 4130 which makes 4150 less susceptible to rusting after fabrication into parts. 4150 also has better weldability than 4130 steel, but 4130 is stronger and less tough than 4150 which makes it a good choice for applications that require high strength or low weight like automotive applications.
