Experimental and Numerical Assessment of Heat-Affected Zone Fracture Toughness in Flux-Cored Arc Welded AISI 1015 Steel

Fracture toughness is a key parameter for assessing structural integrity in welded joints, particularly within the heat-affected zone (HAZ), where microstructural transformations induced by welding may reduce crack resistance. This study proposes and validates an integrated experimental–analytical–numerical methodology for estimating the HAZ fracture toughness in flux-cored arc-welded (FCAW) AISI 1015 steel using non-instrumented Charpy V-notch impact testing. A metallography-assisted computer-aided design protocol ensured accurate and traceable notch positioning within the HAZ before machining. Fracture toughness was estimated by establishing correlations between the impact absorbed energy and the critical stress intensity factor. An energy-based analytical formulation was derived to determine the equivalent dynamic load for finite element coupling, and uncertainty was evaluated using a combined statistical and instrumental contribution framework. The experimentally obtained fracture toughness was KIc = 62.19 ± 1.6 MPa·m1/2 (k = 2, 95% confidence level), while the numerical simulation yielded a value of approximately 77.94 MPa·m1/2, showing reasonable agreement. An approximate 10% reduction relative to the base material confirms that the HAZ is the critical fracture-controlling region. The proposed framework provides a practical and reproducible alternative to conventional fracture mechanics testing.

Charpy impact test; Fracture toughness; Heat-affected zone; Numerical simulation; Welded joints

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