The penetration depth, which indicates the distance from the plate surface to the bottom of the weld pool, is a critical parameter for weld joint quality and is essential in determining weld metal strength. In this study, steel plates were welded using the submerged arc welding method with Boehmite nanoparticles. The study examined the effects of key process input parameters—arc voltage, electric current intensity, electrode stick-out, welding speed, and nano-layer thickness—on weld bead penetration depth. Experimental design techniques, including the five-level five-parameter central composite rotatable design (CCRD) and response surface methodology (RSM), were used to develop an empirical formula. Analysis of variance (ANOVA) was performed to evaluate the adequacy of the empirical formula at a 95% confidence level. Furthermore, the genetic algorithm was applied to optimize input parameter levels to achieve maximum weld penetration depth. The results showed that increasing arc voltage and electric current intensity increased the input heat transferred to the welding pool, leading to wider melting of the base metal and welding wire and consequently increasing penetration depth. Conversely, higher welding speed reduced the input heat transferred to the workpiece.

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