| Dissimilar metal weld (DMW) joints are used throughout both fossil fuel and nuclear power generation facilities to join stainless steel to carbon steel pipes. Joining metals with dissimilar material properties causes stress concentrations to form at the interface, often resulting in premature failure. The present research consists of developing and optimizing a DMW joint to reduce or eliminate stress concentrations. Relying on novel manufacturing processes such as Laser Engineered Net Shaping (LENS), it is possible to produce metal parts in which local material composition can be controlled as a function of position throughout the part. This research proposes grading the metal in a continuous way, from stainless to carbon steel, as well as modifying the geometry to reduce stress in DMW joints. Utilizing a finite element model and optimization routines, exceptional results were realized - maximum stress found in DMWs could be reduced by as much as 80 percent, while at the same time reducing the overall size of the joint. |
