Advanced Structural and Technological Method of Reducing Distortion in Thin-Walled Welded Structures.

Area of Science:

• Materials Science and Engineering
• Manufacturing Processes
• Structural Integrity

Background:

• Welding thin-walled structures, particularly large tanks, often results in significant distortions exceeding permissible standards.
• Traditional Gas Tungsten Arc Welding (GTAW) of stub pipes to steel 1.4301 tanks (1.5 mm wall thickness) led to flatness deviations of 11.9 mm.
• Existing methods lack effective strategies to mitigate these substantial welding-induced deformations.

Purpose of the Study:

• To develop and validate an innovative method for reducing welding distortions in thin-walled structures.
• To investigate the impact of structural and technological changes on joint stiffness and residual stresses.
• To establish a reliable method for predicting and controlling welding distortions in large, thin-walled tank fabrication.

Main Methods:

• Implementation of structural and technological modifications to enhance joint stiffness and introduce a favorable stress state.
• Development and application of finite element method (FEM) numerical models to analyze residual stresses and strains.
• Experimental validation using a custom-built test stand for flange extrusion and ATOS III scanner for distortion measurement.

Main Results:

• The optimized method significantly reduced flatness deviation in welded joints to 0.39 mm, well within standards.
• Numerical models identified a critical flange height (9.2 mm) beyond which extrusion cracks occur.
• Experimental results confirmed the accuracy of FEM simulations and the effectiveness of the developed methodology.

Conclusions:

• The proposed structural and technological changes effectively reduce welding stresses and minimize distortions in thin-walled structures.
• The developed methodology provides a reliable approach for controlling welding distortions in critical applications.
• The study offers a practical solution for achieving high-quality welds in large, thin-walled steel fabrications.