Two steels are being considered for the manufacture of as-forged connecting rods subjected to bending loads. One is AISI (4340 Cr-Mo-Ni steel capable of being heat-treated to a tensile strength of 1800 MPa) and the other is AISI (4140 Cr-Mo steel capable of being heat-treated to a tensile strength of 1600 MPa). Which steel would be a better choice for the connecting rods?
1) AISI 4340 Cr-Mo-Ni steel
2) AISI 4140 Cr-Mo steel