Assess the Effects of Weld Metal and Heat Affected Zone Notch Toughness on Welded Joint Behavior, Considering Different Defects/Imperfections and Strain Rates 

Principal Investigator: Pingsha Dong, Battelle 

    The effort in this sub-task supplements the activities in 5.2.1. Two basic types of specimens are utilized. The first type of tests (both CVN and CTOD) will include basic fracture and material properties. The second is a "welded plate" specimen containing a single bevel CJP weld where failure is initiated in the weld region by selecting a suitable loading condition or by machining a small notch in the surface of the weld. In addition to relatively defect-free test plates, other welded plates with introduced defects will be tested at specified deformation rates to correlate toughness-related material properties and defect characteristics, with basic fracture mechanics principles. These simulated imperfections may represent defects that may not be reliably detected using current UT technology. 

    Tests will be used to assess the ability to predict joint fracture behavior on the basis of the character of defects present, and knowledge of material and fracture toughness properties. Data will be interpreted to help establish estimates of the strength, deformability and failure mode of welded joints as a function of toughness-related material properties for the base and weld metal, load (stress) intensity, and strain rate. This information will be used to help identify desirable toughness-related properties for FCAW-SS welded joints in steel moment-resisting frame connections subject to different strain rates and stress levels. Acceptance criteria will be established for three levels of loading (low, medium and high), as well as three different toughness levels (low, medium and high). 

The detailed breakdown of the technical activities in this task are provided in the workstatement available here.