بررسي مقاومت به خوردگي قطعات جوش فولادهاي زنگ نزن سوپر دوفازي و نقش روش تاگوچي در بهينه سازي پارامترهاي جوشكاري

Optimization of the PCGTAW Parameters for Corrosion Resistance of SDSS Welds Using the Taguchi Method

در اين تحقيق از روش تاگوچي جهت بهينه سازي پارامترهاي موثر بر مقاومت به خوردگي فولادهاي زنگ نزن سوپر دو فازي در جوشكاري قوسي تنگستن- گاز از طريق جريان پالسي استفاده شده است. مقاومت به خوردگي در محيط 3.5% نمك طعام توسط ازمون هاي پلاريزاسيون ارزيابي شد. همچنين اناليز واريانس بر روي داده هاي نسبت سيگنال به نويز صورت گرفت. نتايج ANOVA نشان داد كه پارامترهاي جريان پالس و جريان زمينه كه به ترتيب داراي درصد تاثير 66.28% و 25.97% هستند داراي بيشترين تاثير بر مقاومت به خوردگي جوش هاي فولاد زنگ نزن سوپر دوفازي كه به روشPCGTAW جوشكاري شده اند ، مي باشند. تحت شرايط بهينه، پتانسيل حفره دار شدن 1.06VSCE كه بسيار نزديك به پتانسيل حفره دار شدن پيش بيني شده (1.08 VSCE) است ، به دست آمد. بنابراين روش تاگوچي يك روش سيستماتيك براي بهينه سازي پارامترهاي جوشكاري پالسي شناخته شد.

In the present work, a design of experiment (DOE) technique, the Taguchi method, has been used to optimize the pulsed current gas tungsten arc welding (PCGTAW) parameters for the corrosion protection of super duplex stainless steel (UNS S32760) weld pipes. A L9 (34) orthogonal array (OA) of Taguchi design which involves nine experiments for four parameters (pulse current, background current, % on time, pulse frequency) with three levels was used. Corrosion resistance in 3.5%NaCl solution was evaluated by anodic polarization tests at room temperature. Analysis of variance (ANOVA) is performed on the measured data and S/N (signal to noise) ratios. The higher the better response category was selected to obtain optimum conditions. The optimum conditions providing the highest pitting potential were estimated. The optimum conditions were found as the second level of pulse current (120 A), second level of background current (60 A), third level of % on time (80) and third level of pulse frequency (5 Hz). Under these conditions, pitting potential was predicted as 1.08 VSCE that was very close to the observed value of 1.06 VSCE. As a result of Taguchi analysis in this study, the pulse current was the most influencing parameter on the corrosion resistance and the background current was the next most significant effect. The percentage contributions of the pulse current, the background current, % on time, and pulse frequency to the corrosion resistance are 66.28%, 25.97%, 2.71% and 5.04%, respectively. Consequently, the Taguchi method was found to be promising tool to obtain the optimum conditions for such studies. Moreover the experimental results obtained confirm the adequacy and effectiveness of this approach.