a high strength, high stress steel commonly used in professional race car fabrication. Also known as 4130, this steel is often called "chromoly" because of the Chromium and Molybdenum concentration, which is around .80-1.10 for Chromium and .15-.25 for Molybdenum. The usual tensile strength for 4130 is around 95000-110000 PSI, however it can range as high as 225000 by proper heat treatment (also known as annealing).