Effect Of Welding Process Parameters Research Articles

Modelling and analysis of pitting corrosion resistance of stainless steel overlays deposited by flux cored arc welding process

The present study investigates the effect of welding process parameters on the localised corrosion resistance of AISI 317L stainless steel overlays deposited onto the structural steel plate by flux cored arc welding process. Experiments were conducted adopting response surface methodology concept. The corrosion medium used was 3˙5% neutral NaCl solution (by weight). Potentiodynamic polarisation technique was used for conducting the corrosion tests. Regression equation was developed for modelling the effect of process parameters on the pitting potential. The results indicated that the pitting resistance increased with increasing welding current and speed. However, it started decreasing with further increase in those parameters. Sensitivity analysis indicated that the pitting corrosion resistance is more sensitive to changes in welding speed than the other two parameters.

Study of keyhole closure and analysis of microstructure and mechanical performance of weld joints for variable polarity vertical up plasma arc welding process

Two technical approaches for keyhole closure were conducted. Workpieces of aluminium alloy 2219 were welded using variable polarity vertical up plasma arc welding technology. Effects of welding process parameters on keyhole closure were analysed. Appropriate technical criteria for keyhole closure in the welding of aluminium alloys (3 or 6 mm in thickness) via the variable polarity vertical up plasma arc welding technique were obtained. Experimental simulation of girth welding (overlap welding) was conducted using the appropriate process parameters for the keyhole closure stage of plate butt welding, and the feasibility of circumferential welding was verified. Accordingly, girth welding of the external tank of a carrier rocket was achieved using the appropriate parameters for the keyhole closure technique. In addition, the metallurgical process and mechanical performance for the single pass and overlap welds were analysed and compared.

Analysis of excited droplet oscillation and detachment in active control of metal transfer

Metal transfer in gas metal arc welding (GMAW) plays a very important role in determining the arc stability and weld quality. Based on the analysis of the forces exerted on the droplet, an analytical model is developed to predict the droplet oscillation and detachment process and analyze quantitatively the effect of welding process parameters on the dynamic behavior of metal transfer. The model can be used to guide the optimum design of welding process parameters in achieving one droplet per pulse operational conditions in active control of metal transfer during pulsed current GMAW process.

Numerical and experimental analysis for solidification and residual stress in the GMAW process for AISI 304 stainless steel

Gas Metal Arc Welding (GMAW) process was analyzed by combining a finite element thermomechanical model for temperature and stress with solidification model. Model prediction was compared with experimental data in order to validate the model. The effects of welding process parameters on these welding fields were analyzed and reported. The effort to correlate the residual stress and solidification was initiated, yielding some valuable results. The solidification process was simulated using the formulation based on the Hunt-Trivedi model. Based on the temperature history, solidification speed and primary dendrite arm spacing were predicted at given nodes of interest. Results show that the variation during solidification is usually within an order of magnitude. The temperature gradient was generally in the range of 104–105 K/m for the given welding conditions (welding power = 6 kW and welding speed = 3.39 to 7.62 mm/sec), while solidification speed appeared to slow down from an order of 10−2 to 10−3 m/sec during solidification. SEM images revealed that the Primary Dendrite Arm Spacing (PDAS) fell in the range of 101−102 μm. The range of predicted sizes was in agreement with the experimental values. It was observed that the average size of the PDAS was dependent upon the welding speed. The PDAS fell between 7.5 to 20 μm for columnar and 10 to 30 μm for equiaxed dendrites, for welding speeds between 3.39 to 7.62 mm/sec. When the welding speed increased, it was observed that the average size of the PDAS decreased, as the model had predicted. For grain growth at the Heat Affected Zone (HAZ), Ashby's model was employed, and the prediction was in agreement with experimental results. For the residual stress calculation, the same mesh generation used in the heat transfer analysis was applied to make the simulation consistent. The analysis consisted of a transient heat analysis followed by a thermal stress analysis. An experimentally measured strain history was compared with the simulated result. The relationship between microstructure and the stress/strain field of welding was also obtained.

Mathematical models for control of weld bead penetration in the GMAW process

This paper presents the effects of welding process parameters on weld bead penetration for the gas metal arc welding (GMAW) process. Welding process parameters included wire diameter, gas flow rate, welding speed, arc current and welding voltage. The experimental results have shown that weld bead penetration increased as wire diameter, arc current and welding voltage increased, whereas an increase in welding speed was found to decrease the weld bead penetration. However, the weld bead penetration is not affected significantly by gas flow rate changes. Mathematical equations for study of the relationship between welding process parameters and weld bead penetration have also been computed by employing a standard statistical package program, SAS.

The effects of welding process parameters on the metallurgical characteristics of stainless steel cladding and their influence on ultrasonic inspection of PWR pressure vessels: Allen, D.J.; Stansfield, A.M. Central Electricity Generating Board, Southampton (United Kingdom), CEGB-TRPD-M-1634-R-87, 13 pp. (Oct. 1987)

The effects of welding process parameters on the metallurgical characteristics of stainless steel cladding and their influence on ultrasonic inspection of PWR pressure vessels: Allen, D.J.; Stansfield, A.M. Central Electricity Generating Board, Southampton (United Kingdom), CEGB-TRPD-M-1634-R-87, 13 pp. (Oct. 1987)