This is the fifth report of a series of seven reports detailing the small-scale mechanical testing performed on the trial welds in this consolidated program. An outline of the reporting flow is given in the Introduction to the Summary of Mechanical Properties report 277-T-08. The present report contains the results of application of the low-constraint tensile toughness test, supplemented with results of shallow-notch bend tests, to the three series of welds in the consolidated program, including tests on base metal, weld metal, and HAZ.