Optimization of pulsed current gas tungsten arc welding process parameters to attain maximum tensile strength in AZ31B magnesium alloy

An empirical relationship to predict tensile strength of pulsed current gas tungsten arc welded AZ31B magnesium alloy was developed. Incorporating process parameters such as peak current, base current, pulse frequency and pulse on time were studied. The experiments were conducted based on a four-factor, five-level, central composite design matrix. The developed empirical relationship can be effectively used to predict the tensile strength of pulsed current gas tungsten arc welded AZ31B magnesium alloy joints at 95% confidence level. The results indicate that pulse frequency has the greatest influence on tensile strength, followed by peak current, pulse on time and base current.

Improvement of Microstructure and Mechanical Behavior of Gas Tungsten Arc Weldments of Alloy C-276 by Current Pulsing

Superalloy C-276 is known to be prone to hot cracking during fusion welding by Gas Tungsten Arc method. Microsegregation occurring during cooling of fusion zone with consequent appearance of topologically close-packed phases P and IX has been held responsible for the observed hot cracking. The present work investigated the possibility of suppressing the microsegregation in weldments by resorting to current pulse. Weldments were made by continuous current gas tungsten arc welding and pulsed current gas tungsten arc welding using ERNiCrMo-4 filler wire. The weld joints were studied with respect to microstructure, microsegregation, and mechanical properties. Optical microscopy and scanning electron microscopy were employed to study the microstructure. Energy-Dispersive X-ray Spectroscopy was carried out to evaluate the extent of microsegregation. Tensile testing was carried out to determine the strength and ductility. The results show that the joints fabricated with pulsed current gave rise to narrower welds with practically no heat affected zone, a refined microstructure in the fusion zone, reduced microsegregation, and superior combination of mechanical properties.

Mechanical and corrosion properties of 445J2 ultra pure ferritic stainless steel joint

The microstracture, mechanical and corrosion resistance properties of 445J2 ultra pure ferritic stainless steel thin plate joints conducted by the pulsed current gas tungsten arc welding （PCGTAW） were discussed in this paper. In order to avoid weld defects, the appropriate welding process was adjusted. The joints were subjected to optical microscopy, transverse static tensile, plastic deformation, intergranular corrosion and electrochemistry corrosion tests. The results indicated that the weld zone （WZ） is characterized with columnar grains and equiaxed grains and the heat-affected zone （HAZ） shows coarse ferrite grains due to the rapid solidification of thin plate welding. The PCGTAW joint exhibited acceptable mechanical properties and equivalent corrosion resistance properties as the base metal.

Influence of Filler Metals in the Control of Deleterious Phases During the Multi-pass Welding of Inconel 718 Plates

The present study reported the effect of filler metals on the microstructure and mechanical properties of pulsed current gas tungsten arc-welded Inconel 718 plates. Two different filler metals such as ERNiCr-3 and ERNiCrMo-4 were employed for welding Inconel 718. The primary objective of this study is to suppress or eradicate the deleterious phase such as Laves or δ （delta） which is considered to be detrimental to the weld properties. Microstructure examination corroborated the presence of unmixed zone at the HAZ for both the weldments. Tensile test trials envisaged that ERNiCrMo-4 weldments offered better tensile properties compared to ERNiCr-3 weldments, whereas the impact toughness was found to be better for ERNiCr-3 weldments. Line mapping analysis was carried out to study the elemental migration across the weldments. The structure-property relationships of the weldments were arrived at using the combined tech- niques of optical and scanning electron microscopy. Optical and SEM/EDAX analysis showed that there is no prominent occurrence of deleterious phases at the weld zone on employing these filler metals.