Cold Cracking Susceptibility of Weld Metal Deposited by Gas Shielded Rutile Flux-Cored Wire

This paper presents the results of an investigation of the hydrogen assisted cold cracking (HACC) susceptibility of low strength rutile flux-cored seamless (H5) and seamed (H10) wires, with nominal diffusible hydrogen (HD) levels of 5 and 10 mUlOO g, respectively. The objective was to assess the influence of key welding parameters on the susceptibility of the weld metal to cold cracking. Parameters investigated were the welding current, the contact-tip to work-piece distance (CTWD), the shielding gas and the preheat temperature. The gapped bead-on-plate (G-BOP) test was used to examine the effects of these parameters on weld metal transverse cracking. Tests were carried out at different preheat temperatures and the percentage of cracking was recorded. It was found that, without preheat, the H5 wire weld deposits did not crack, whereas all those produced using the H10 wire exhibited cold cracking. The overall results indicate that the susceptibility to cold cracking strongly correlates with HD. Apart from the intrinsic hydrogen content of the wire, the concentration in the deposit is affected by the welding current, the CTWD, the shielding gas and the preheat temperature. Preheat has a strong effect and was found to substantially decrease the amount of cold cracking in the H10 welds. Further, weld metal deposited using 75Ar-25C02 shielding gas resulted in higher Hd levels than f r C 0 2 shielding and a higher susceptibility to cold cracking for no or low preheat.