Determining the Optimal Amount of Oxide Flux in A-TIG Welding of HSLA-100 Steel

The HSLA-100 steel is a newcomer steel produced by USA navy that have many applications in the marine environment structures due to its high strength and toughness. In present study the effect of SiO2 and TiO2 fluxes content on weld geometry, arc voltage and micro hardness of weld different regions of HSLA-100 steel with 5.4 mm were studied. At first oxide fluxes SiO2 and TiO2 with surface density in the range of 0-55 mg/cm2 was applied on joint, then bead on plate TIG welds are carried out. Due to determine the feasibility of industrialization and applying a uniform coating, fluxes were applied to the connection by spraying method. The results showed that depth to width ratio for SiO2 and TiO2 fluxes initially increases sharply with surface flux density increase and subsequently becoming approximately constant (1.14 and 0.51 were obtained respectively). Maximum penetration depth of 6.18 mm for A-TIG is obtained for SiO2 flux in surface flux density range 5.5 to 10 mg/cm2. Also, by increase of SiO2 surface flux density sharp arc voltage increase was observed from 13 to 16.6 V that causes heat input increase and subsequently hardness decrease. When using TiO2 flux arc voltage value fell, there was no significant change.