AISI 4130 is a chromium-molybdenum steel is widely preferred due to its well-established heat-treating properties and processing efficiency. As well as tubing, It is also available in all sizes of sheets, plates and bars. Bar stock of this material is also used for small forgings under one-half inch in thickness. AISI 4135, a slightly higher carbon version of AISI 4130, is also available in same shape forms.