Measurement of strengths and fracture initiation strains of weld metal and HAZ in steel joints using miniature coupons

This paper investigates the strengths (fy, fu) and fracture initiation strains (εf) of the weld and heat affected zone (HAZ) of welded joints. Miniature coupons were extracted and tested using a custom-built jig. The weld metal was generally isotropic with the highest and lowest εf in the longitudinal and transverse directions, respectively. The HAZ had higher fy and fu than the base metal but smaller εf in the transverse direction under low stress triaxiality, indicating possible fracture through the weld and HAZ when loaded transversely. The strengths of the weld metal and HAZ can be approximated to within 7%-10% using empirical hardness-strength correlation functions.