Influence of inhomogeneity on several length scales on the local mechanical properties in V-alloyed all-weld metal

Recently, a new, vanadium alloyed welding consumable with a minimum yield strength of 1100 MPa was developed. The mechanical properties of welding consumables for gas metal arc welding are usually classified by producing and testing all-weld metal samples, which are typically a multipass weld. Chemical and microstructural fluctuations of a vanadium alloyed all-weld metal sample on a macro- and microscale and their influence on the local mechanical properties were investigated. On a macroscale, hardness mappings show a pattern of hard and soft zones which can differ up to 60 HV. Despite the existence of these fluctuations, undersized Charpy V-notch tests revealed no significant difference between the last weld bead and the underlying ones. It is explained how vanadium and its tendency to form precipitates affect both the hardness inhomogeneity and the toughness homogeneity. On a microscale, segregations of several alloying elements and significant grain size fluctuations were found. Their influence on fluctuations of the mechanical properties is discussed as well.