The research was carried out with the aim of statistically investigating the effect of shielding gas on the tensile properties of high carbon steel weldment using Tungsten Inert Gas (TIG) in combination of argon and carbon (iv) oxide gases. TIG welding technique was used to join the weld. An experiment was designed using the design expert software 10.0.1 version, which developed a combined mixture design of twenty seven experimental runs. The combined and process factor design was applied to statistically analyze the effect of shielding gas on the yield strength of the weldment. The statistical evaluation consists of mixture and process variable, having current, voltage, argon and carbon (iv) oxide gases as input parameters and yield strength as the response. The result obtained from the design summary gave minimum value of tensile strength as 280MPa and maximum 485MPa while mean value was 369.82 and standard deviation of 46.94. Fit Summary statistics which gave quadratic by quadratic order having sequential p values of less than 0.0001 for both mix and process orders with predicted R squared value of 0.9823 and Adjusted R squared value of 0.9959 which shows that the model is significant. Analysis of Variance (ANOVA) also showed that the model is significant while the Goodness of fit statistics obtained showed adequate precision value of 80.710 which showed that the signal to noise ratio was adequate and can be used to navigate the design space. The normality plot revealed that the computed residuals are approximately normally distributed an indication that the model developed is satisfactory while the presence of outliers were not noticed in the cook’s distance plot. This study reveals that argon gas combining with carbon (iv) oxide will produce weldments with high tensile strength as could be seen in the statistical analysis.

Full text: IJEIR_2461_FINAL.pdf