two steels are being considered for manufacture of as-forged connecting rods. one is aisi 4340 cr-mo-ni steel capable of being heat-treated to a tensile strength of 260 kpsi. the other is a plain carbon steel aisi 1040 with an sut of 113 kpsi. if each rod is to have a size giving an equivalent diameter de of 0.75 in., is there any advantage to using the alloy steel for this fatigue application?