Fabricated metallic structures originate as plate stock at the material manufacturer. The residual stresses in the plate stock depend on the steel manufacturing process and the heat treatment and cooling methods applied. The residual history is then carried through and is altered by the cutting, bending, welding, etc. required for the fabrication. This process can create additional residual stresses and/or will alter the residual stress or distortion throughout the parts and components. As will be seen, by the time the material from the steel plant makes its way into the service structure, each component has already seen a history of stresses, nonlinear strains, and corresponding displacements. This history can have an important effect on the service life of the structure. Fatigue, corrosion cracking, fracture, etc. can all be affected by prior history. However, in most cases this prior history is neglected in design or when making a damage assessment of the structure. Fatigue and fracture assessments are often made by pretending that the service material is pristine, free of prior fabrication history effects. The fatigue life, corrosion response, and final fracture behavior predicted assuming a pristine structure can be different from that which would be predicted by including prior history.
This paper illustrates the effect of prior history on weld-fabricated structures through the use of several examples. The fatigue behavior, the corrosion response, and the final fracture behavior for several cases where history effects are included are compared with predictions where these effects are neglected. Guidelines for determining when prior fabrication effects must be included in the design and life management process are provided. Finally, simple methods for accounting for these in the design and life management cycle are overviewed.