Analysis of repetitive repair welding on properties on stainless steel to carbon steel dissimilar metal joints

Repair welding of dissimilar material is frequently used in steel structures to replace the weldment defect and prolong the material service life. Generally, repair welding is a crucial topic that needs more discussion due to the lack of application in real industry. In order to reduce cost and depe...

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Bibliographic Details
Main Author: Laily, Suraya
Format: Thesis
Language:English
English
Published: 2023
Online Access:http://eprints.utem.edu.my/id/eprint/27024/1/Analysis%20of%20repetitive%20repair%20welding%20on%20properties%20on%20stainless%20steel%20to%20carbon%20steel%20dissimilar%20metal%20joints.pdf
http://eprints.utem.edu.my/id/eprint/27024/2/Analysis%20of%20repetitive%20repair%20welding%20on%20properties%20on%20stainless%20steel%20to%20carbon%20steel%20dissimilar%20metal%20joints.pdf
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Summary:Repair welding of dissimilar material is frequently used in steel structures to replace the weldment defect and prolong the material service life. Generally, repair welding is a crucial topic that needs more discussion due to the lack of application in real industry. In order to reduce cost and dependence on the high skilled welders, repair welding on dissimilar pipe materials Stainless Steel 304 (AISI 304) and Carbon steel 1387 (BS 1387) were performed using Gas Metal Arc Welding (GMAW) with 100 mm each long. Furthermore, dissimilar is not just the material but also the diameter of the pipes. Fixed nozzle rotational jig was used as the main welding equipment with current (A), voltage (V) and rotational speed (rpm) as the main parameter. The study was focused on the effect of repair welding on mechanical properties, microstructure formation of AISI 304 and BS 1387 and prediction of service life of the dissimilar material repaire welded pipes. Tensile, microhardness, and fatigue tests were performed with nine runs of samples with three times of repetition as a planning matrix generated by Minitab Software. Design of Experiment (DOE) was used to plan the whole project using Taguchi Method as the main platform. Prediction of tensile testing and fatigue testing failure location was performed using ANSYS software. The outcome of the study shows that repair welding affected the performance of weldment, especially on mechanical properties. Tensile and microhardness testing showed the highest value on the second repair, while fatigue testing on the third repair. The heat generated during the welding process also affects the Heat Affected Zone (HAZ), and the microstructure formation of them was discussed. The regression equation of each repair was generated, and validation error was calculated. Prediction of the pipe service life schedule was performed using an FMEA chart in order to have a proper preventive maintenance schedule.