THERMAL STRESSES IN LARGE BUTT-WELDED PLATES

In shipyard panel-production lines several rectangular plates are butt welded to form large panels. One problem is the tendency of hot cracking in the end portion of the butt weld. In this paper transient temperature fields and stress fields in butt-welded plates are calculated using the finite-element method. The calculations are performed for different welding speeds, for different heat inputs, and for one-sided and two-sided welding. The calculated temperature fields and stress fields are compared to available experimental data. In general, good agreement is found. The location of the calculated maximum transverse tensile stresses and strains are compared to the location of hot cracks from available data. It is concluded that the hot cracks may nucleate at temperatures around l200°C due to high transverse tensile strains. The cracks may then propagate at a temperature of about 400° C, when the maximum transverse tensile stresses arise. The influence of the welding speed on the formation of hot cracks s...