Changes in the mechanical properties of plain carbon and alloy steels that are caused by fast neutron irradiation are presented in graphic form. These data were abstracted from classified and unclassified reports published since 1948 by USAEC, AECL, and AERE. Data are included for the following steels: A- 105-55T, A-106, A-200-55T-T22 (Croloy), A-201, A-242, A-301-B, A-302-B, AlSI-C- 1013, AISI-C-1065, SA-70, SA-193,4, SA-212, SA-285, SA-336, SAE-1018, SAE-1020, SAE-1042, SAE-1045, SAE-1095, SAE-1113, SAE-1141, SAE-4130, and SAE-4340. The mechanical properties for which data are reported include hardness, yield strength, tensile strength, total and uniform elongation, reduction of area, fatigue strength, notch factor, creep, impact energy, and transition temperature. (auth)