Optimizing Welding Sequence and Improving Welding Process for Marine Thick-Walled Circular Pipes.

Area of Science:

• Welding Engineering
• Materials Science
• Mechanical Engineering

Background:

• Automated welding of thick-walled pipes in shipbuilding often suffers from significant deformation and reduced quality.
• Controlling welding-induced stresses and distortions is critical for structural integrity and performance.

Purpose of the Study:

• To propose a strategy for optimizing segmented multi-layer multi-pass welding sequences.
• To improve welding quality by reducing deformation and residual stress in thick-walled pipes.

Main Methods:

• Developed a welding model and established a multi-layer multi-pass welding trajectory equation for thick-walled pipes.
• Utilized a double-ellipsoidal moving heat source model for simulation.
• Employed welding finite element analysis (FEA) to simulate and compare four segmented welding sequences on pipe workpieces of varying wall thicknesses.

Main Results:

• The skip-symmetric welding sequence demonstrated superior performance for thick-walled circular pipes.
• This method reduced welding deformation by an average of 6.50% and welding stress by 5.37% compared to other sequences.
• Optimized welding parameters were identified for different pipe thicknesses (10, 15, and 20 mm) to achieve the best welding quality.

Conclusions:

• The proposed segmented welding sequence optimization strategy effectively minimizes welding deformation and residual stress.
• The skip-symmetric method is recommended for automated welding of thick-walled pipes in shipbuilding.
• Optimized process parameters enhance welding quality, ensuring structural integrity.