Shielding gas

About: Shielding gas is a research topic. Over the lifetime, 6697 publications have been published within this topic receiving 58668 citations.

Comparison of bead shape, microstructure and mechanical properties of fiber laser beam welding of 2 mm thick plates of Ti-6Al-4V alloy

Abstract: Fiber laser beam welding experiments are carried out on 2 mm thick plates of Ti-6Al-4V alloy at various welding conditions. A specially designed workpiece fixture with shielding gas delivery system is fabricated and effectiveness of shielding gas is confirmed by energy dispersive X-ray spectroscopy analysis. Two different types of bead cross-sections i.e. T-shaped and nearly X-shaped beads are observed at different line energies. After experiments, width and area of fusion zone and size of heat affected zone are measured and further analyzed. The microstructural studies at different locations in heat affected zone and also in fusion zone are carried out with optical microscope and their morphologies are compared at different welding conditions using field emission scanning electron microscope. The porosities are observed in both T and X-shaped weld beads at different line energies. However, their sizes are in acceptable range as per BS EN:4678 standard. The maximum microhardness is found in fusion zone due to the presence of large amount of α′ martensite. The line energy utilization factor is higher for T-shaped bead than X-shaped bead. The tensile strength of T-shaped bead is lower than X-shaped bead due to higher non-uniformity in the distribution of plastic strain. The experimental results show that T-shaped welding conditions are favorable while considering full penetration in keyhole mode, narrower weld width and lesser heat affected zone.

Reactive gas shielding during laser surface alloying for production of hard coatings

Abstract: The effects of nitrogen addition to shielding gas during laser surface alloying with a mixture of 80 wt.% 431-type stainless steel and 20 wt.% titanium carbide powders were investigated. Microstructural characterization of the laser deposits indicated that titanium carbide melted and re-precipitated as fine carbides from the liquid melt during cooling. With 100% nitrogen shielding and the same powder mixtures, a deposition with increased hardness was obtained. The microstructural evolution in the deposit was calculated with equilibrium thermodynamic calculations.

Welding electrode and method for reducing manganese in fume

Abstract: A cored electrode for arc welding, said electrode having a core in which the fill material incudes a manganese-containing composite particle.

Simulation of Active Shielding Gas Impact on Heat Distribution in the Weld Zone

Abstract: Controlling the processes, which take place during consumable-electrode shield-gas welding, is one of the main problems of the welding industry. The paper shows that under the certain conditions the electrode-metal drop and heat distribution in the weld area are influenced by the active shielding gas jet. The paper provides the results of modeling heat distribution in the weld area and active shielding gas outflow from the traditional and double-jet welding torch nozzles.

An Experimental and Numerical Approach for the Welding Effects on the Duplex Stainless Steel Microstructure

Abstract: Key microstructural changes that occur when Duplex Stainless Steels (DSS) are welded could be evaluated when bead-on-plate welding was carried out on a 2205 DSS by the GMAW process. By using numerical simulations, it was possible to calculate locally the heating and cooling rates taking place during the 2205 DSS welding and discuss its correlation to the microstructural changes experimented by the parent metal. Results showed that increasing heat input has promoted the ferritic grain growth with a slight reduction in the austenite content present at the high temperature heat affected zone (HTHAZ), whereas the cooling rates remained above from those reported as critical for sigma phase precipitation in 2205 DSS. Furthermore, nitrogen has proved to be an effective austenite former at the fusion zone (FZ), which can contributes to get a balanced microstructure in DSS welds in contrast to the effects from the elevated cooling rates.