4130 steel has a minimum yield or tensile strength at 55 KSI (80,000 PSI). This means that if you were to pull on two 4130 steel pieces with a force of 55,000 pounds per square inch (PSI) they would break. 4130 is much stronger than 4150 or 4340 but it also weighs more as well making 4130 best for applications that require high strength and low weight.
