WRIGHT AIR DEVELOPMENT CENTER WRIGHT-PATTERSON AFB OH
Mechanical properties of a chrome-nickel-molybdenum-vanadium general purpose medium carbon alloy steel modified SAE 4330 plus vanadium, developed by the Republic Steel Corporation, were determined to evaluate the suitability of the steel for aircraft applications. The properties of the Republic alloy steel were compared with the properties of an alloy steel, designated as Hy- Tuf, and with the properties of the well established SAE 4340 general purpose alloy steel. When heat treated to the same nominal hardness and strength levels, the Republic steel had approximately the same percentages of elongation and reduction of area as the other steels. The Republic alloy steel showed superior Izod impact properties to those of Hy-Tuf and SAE 4340 alloy steels when each was heat treated to a tensile strength approximating 170,000 psi Rockwell C39 both at room and low temperatures, but its impact properties were not as high as those for Hy-Tuf when heat treated to strength levels around 220,000 psi either at room or low temperatures. Both the Republic alloy steel and Hy-Tuf alloy steel had impact properties superior to those of SAE 4340 alloy steel.