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The selective laser melting (SLM) method is being increasingly applied in the aerospace and power industries for the production of high temperature critical components. The effects of SLM processing parameters, such as laser power, scanning speed, and energy density on the creep properties were investigated for 316L stainless steel (SS316L). The effect of building direction was also studied. The creep resistance was influenced by the manufacturing direction. The vertical specimen demonstrated a longer creep life and higher creep resistance than the horizontal specimen. The creep resistance remained constant when the energy density was kept constant during manufacturing. If insufficient energy density was used for manufacturing, internal defects, such as voids and unmelt powder were generated, and lowered the creep resistance. However, if sufficient energy density higher than a minimum value was employed, the material creep properties mainly depended on the level of the energy density.

Creep deformation and rupture behavior of welded joints from service‐exposed P91 steel were investigated by creep tests and microstructure examination. A series of miniature tensile creep tests were conducted at 569°C under applied stresses ranging from 182.5 to 286 MPa for the heat‐affected zone (HAZ), base metal, and weld metal. Creep deformation behavior was modeled using the experimentally measured creep strain data as the primary creep‐secondary creep (PC‐SC) model and fitting closely with the measured creep curves of each metal. Power‐law type creep equations were employed to describe the primary and secondary creep behavior. The creep rupture life of the cross‐weld specimen was predicted using the PC‐SC model with HAZ properties. An accurate prediction was possible if the stress in estimation was increased to 1.14 times of the actual applied stress. The creep test results with the cross‐weld specimens were used for verification. Applying the Monkman–Grant relationship and the creep damage tolerance factors to the cross‐weld joint life prediction are also discussed.