The chassis material for this sand rail has 2 options.
Each option has positive and negative aspects.
Chromoly - It is stronger and lighter than mild steel. The commonly used welding process used for chromoly is known as TIG. Cost of chromoly is greater than that of mild steel. The chromoly must be purchased and shipped from an out of state supplier.
Mild steel - Not as strong as chromoly and weighs more. The common welding process used for mild steel is known as MIG. Cost of mild steel is cheaper than that of chromoly. The mild steel can be purchased from a supplier that is within driving distance.
While I have access to both TIG and MIG welding equipment in the shop, it is easier for me to transport and power a MIG welder to the field for repairs if needed.
I have made the decision to build the chassis for this rail out of mild steel to keep the costs lower and the ability to make field repairs if needed.