Penetration Estimation of GTAW with C-Type Filler by Net Heat Input Ratio

Abstract

This study proposes a novel method to estimate the weld penetration in gas tungsten arc welding (GTAW) with filler metal. So far, there is no standard parameter available to accurately estimate penetration in GTAW with filler metal. Until now, the penetration could be estimated by heat input only in GTAW with and without filler metal. But in this study, it was revealed that the conventional heat input could not accurately estimate the penetration in GTAW with filler metal. Therefore, the new concept of net heat input ratio (NHIR), which is a ratio of net heat input to the bead cross-sectional area, was developed to accurately estimate the penetration in GTAW with filler metal. Using a C-type filler metal during GTAW, the NHIR was calculated for various welding conditions. The results showed that the NHIR was proportional to the welding current and voltage and inversely proportional to the welding speed and filler feed speed. Even though the NHIR was the same, the penetration increased as the welding current became higher. Four linear equations between NHIR and penetration were obtained from the experimental results for four levels of welding currents. By applying the concept of NHIR, the penetration could be estimated for any welding current.