Modeling and optimization of dilution in SAW in the presence of Cr2O3 nano-particles

Abstract

Dilution is an important quality characteristic in welding, since it influences performance of welded/surfaced structures in service due to chemical and metallurgical changes in weld metal. The main objective of the present study is to develop an empirical formula for optimization of percentage dilution as affected by the combined effect of welding input parameters such as arc voltage, welding current, contact tip-to-plate distance, welding speed, and Cr2O3 nano-particles in submerged arc welding (SAW) process. The five-level five-parameter central composite rotatable design (CCRD) and response surface methodology (RSM) were used to develop empirical formula. Analysis of variance (ANOVA) was conducted to test adequacy of the empirical formula at 95 % confidence level. The remarkable result of this investigation indicates that arc constriction is another mechanism which controls percentage dilution in SAW process. The results show that changing the thickness of Cr2O3 nano-particles from 0 to 0.25 mm increased percentage dilution from 61.5 to 62.8, whereas changing the thickness from 0.25 to 0.75 mm decreased percentage dilution from 62.8 to 59.9. However, above the thickness of 0.75 mm, percentage dilution increased from 59.9 to 60.9. Finally, the results of confirmation experiments showed that error of the empirical formula was less than 5 %.