Year

2013

Degree Name

Master of Engineering

Department

School of Mechanical, Materials and Mechatronic Engineering

Abstract

The reduction of welding induced distortion has become an important focus of research for the shipbuilding industry with the continuing trend of using thinner steel plates in the ship’s hull and super structure. In this thesis, two recently developed processes Tandem Gas Metal Arc Welding (T-GMAW) and the Dynamically Controlled Low Stress No Distortion (DC-LSND) processes were investigated to reduce welding distortion. T-GMAW has been widely applied in production but its effect on low distortion welding of ship panel welding is unknown. Most studies on DC-LSND process are applied on thin plates with a thickness of 1 to 2 mm, while there is no existing study on ship panels with medium thickness, 5 to 6mm. A feasibility study of replacing existing Submerged Arc Welding (SAW) with T-GMAW for ship panel welding, as well as using DC-LSND technology for welding 5 mm DH36 shipbuilding steel is provided in this thesis. The performance of both T-GMAW and DC-LSND was investigated by examining the microstructure/ macrostructure, hardness test, impact toughness test and residual stress measurement. The experimental results showed that welds done by T-GMAW had better microstructure, lower residual stress than SAW welds, and DC-LSND process showed a hardening and brittle tendency in welds by Charpy impact toughness test.

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