Heterogeneity Estimation of Low-Cycled Steel Weld Probes

Abstract

The heterogeneity of manual arc welded samples of low-carbon steel St3sp meant for bridge construction to be used in Cameroon has been investigated. The chemical analysis of the material was carried out and the arc welding processes used, then the probes were subject to mechanical testing such as tensile test, low-cycle fatigue test, and micro hardness study. A total inclusion of weld defects in the specific welded sample and especially in the cyclic loading specimes has been discovered. Premature fracture was revealed below the plastic limit in some probes during the tension and low-cycle test. A micro structural examination and micro hardness measurements were done in order to determine what exactly could be the reason of this catastrophic failure. The structural analysis revealed the differences in mechanical properties conditioned by phase distribution and carbon content in weld, heat affected zone and base metal. To determine the heterogeneity in mechanical properties the elastic modulus distribution has been calculated due to relationship between the micro hardness and materials strength.