| Abstract Scope |
The Charpy V-notch (CVN) impact test is the primary method for evaluating fracture toughness in welded steels; however, current qualification standards provide inconsistent guidance for notch placement within the heat-affected zone (HAZ). Recommendations vary between placement at the fusion line, a specified offset, or to maximize HAZ inclusion, leading to uncertainty in whether minimum HAZ toughness was obtained. This study quantifies the effect of notch-tip location on measured CVN toughness and evaluates whether a standardized placement can reliably identify the lowest-toughness region of a welded joint.
Three submerged arc welds were produced in 25 mm (1”) ASTM A36 plate using a 45° single-V groove geometry with a 1/4” root opening, no land, and backing. Welding was performed in nine passes using 3/32” LA-12K wire and Blue Shield LA-59 flux at 30 V, 500 A, and 10 ipm travel speed. Metallographic examination and microhardness testing confirmed weld-to-weld consistency and characterized weld metal, HAZ subregions, and parent microstructure prior to impact testing.
Charpy specimens were prepared such that notch-tip locations progressed in 1 mm increments through the weld metal and HAZ. Five notch locations were evaluated on the vertical fusion boundary and fifteen across the 45° fusion boundary. Specimens were etched using 4% Nital to identify notch-tip position. Five specimens were tested at each location in accordance with AWS D1.1, Option B.
Results will establish the relationship between notch placement and measured impact energy and assess whether a single notch placement can consistently capture the minimum HAZ toughness. Fracture initiation behavior will be correlated with specific HAZ subregions to determine their influence on CVN response. Findings are expected to provide practical guidance for HAZ toughness testing and inform future revisions to welding qualification standards, including AWS D1.1, ASME Section IX, and other codes governing impact testing of welded structures. |