Prediction, Optimization and Automatic Generation of Robotic Gas Metal Arc Welding Process Parameters for AISI SAE 4130 Alloy Steel

Abstract

Robot-Based Gas Metal Arc Welding (Gmaw) Process Has Increased The Welding Process Efficiency And Empowered The Fabrication Industries With Complex Weld Paths. The Selection Of Process Parameters And Their Combinations Affect The Weld Bead Geometry And Mechanical Properties Of The Materials To Be Welded. The Selection Of Input Parameters Should Be Based On The Weld Path The Robot Has Followed, Weld Quality Level Requirement, Material Type And Thickness. In This Dissertation Work, Wire Feed Rate (Wfr), Travel Speed(Ts), Contact Tip To Work Distance (Ctwd), And Electrode Work Angle (Ewa), Were Considered As Input Parameters For A Specific Range To Weld ?�?T?�?-Joints Of Aisi Sae 4130Alloy Steel Of 2, 4 And 6mm Thicknesses. A Set Of Experiments Were Performed By Using Doe Methods. An Artificial Intelligence System Was Used For Quality-Level-Based (B, C, And D)Prediction Of Welding Parameters And Response Surface Methodology Of The Central Composite Design Technique And Mathematical Models Were Developed. Analysis Of Variance And Lack Of Fit Test Were Verified To Determine Any Statistically Significant Welding Parameters. Break Strength, Throat Thickness, Joint Penetration, Micro-Hardness Test And Microstructure Examination Were Investigated And Evaluated Under Significant Welding Parameters. A Prediction Profiler With A Desirability Function Was Used And Predicted The Optimal Combination Of Welding Parameters For A Set Of (35??, 40??, 45??, 50??, And 55??) Ewa. For The Remaining Accessible Range Of Ewa From 35?? To 55??, The Data Has Been Auto-Generated Using Cubic Spline Interpolations Methods. The Microstructural Changes In The Weld Zone, The Extent Of Haz In Both (Horizontal And Vertical) Plates And The Variation In Hardness Across Joints Have Been Investigated. The Optimal Break Strength Of 67.45kn And Joint Penetration Of 3.71mm Were Predicted At Wfr Of 8.29m/Min, Ts Is 243mm/Min, EwaIs 40?? And Ctwd Is 10mm Parameters. In Case Of 35??? Ewa: Wrr=9m/Min,Ts=358.78mm/Min, And Ctwd=16.22mm; 45??? Ewa: Wer=7m/Min, Ts=418.98mm/Min,And Ctwd=10mm; 50??? Ewa: Wfr=7.40m/Min, Ts=159.26mm/Min And Ctwd=16.63mm; And 55??? Ewa: Wfr=7.26m/Min, Ts=281.31mm/Min And Ctwd=14.38mm Were Noted As Optimal Welding Parameters. Microstructural Examination Revealed That At Lower Wfr (3m/Min) And Higher Ts (450 Mm/Min), Lower Heat Input And A Faster Cooling Rate Were Observed, Resulting In A Fine-Grain Structure In The Weldments. Conversely, Higher Wfr (9m/Min) And Lower Ts (150mm/Min) Produced More Heat Input And A Slower Cooling Rate, Resulting In A Coarse Grain Structure In The Weldments. The Recorded Average Crystallite Size Of The Base Metal And Fusion Zone Is25.75nm And 24.5nm Respectively. The Greatest Extent Of The Haz (956.08??M) Was Observed At 3m/Min Wfr, 150mm/Min Ts, 55?? Ewa, And 20mm Ctwd On The Vertical Plate. Whereas, The Lowest Extent Of Haz On The Horizontal Plate Was 298.99??M, At 7m/MinWfr, 350mm/Min Ts, 35?? Ewa, And 15mm Ctwd. The Optimized And Automatically Generated Welding Parameters Facilitate The Automatic Control System Of A Robotic Gmaw Process Which Will Raise The Programmable Efficiency Of The Welding Robot.