16Mo3 (1.5415) is a molybdenum-alloyed low-carbon steel widely used in power plant boiler components such as waterwalls, superheater tubes, and steam pipelines. Its creep resistance is primarily attributable to molybdenum in solid solution, which strengthens the ferritic matrix and slows microstructural degradation at elevated temperatures. At 550°C, 16Mo3 exhibits a creep strength of approximately 60 MPa after 100,000 hours of exposure—representing a 40–60% improvement over non-alloyed steels such as P235GH. More detailed data show creep rupture strengths of 285 MPa at 450°C, 190 MPa at 500°C, and 94 MPa at 520°C for the same duration. These properties make 16Mo3 suitable for continuous operation at temperatures up to 530°C.
However, the material has significant limitations under sustained high-temperature creep stress. The absence of strong carbide-forming elements such as chromium reduces its long-term structural stability, particularly above 450°C. Prolonged exposure promotes graphitization—the decomposition of cementite into graphite nodules—which can compromise load-bearing capacity, especially when graphite forms chains in weld heat-affected zones. A documented failure of a 16Mo3 pipeline bend occurred after nearly 180,000 hours of operation when the actual service temperature exceeded the recommended 470°C maximum due to changes in fuel mix, leading to extensive graphitization and cavitation damage. Below 430°C, graphitization is extremely slow, but at higher temperatures the risk escalates.
In conclusion, 16Mo3 can withstand moderate creep stress in power plant boilers up to approximately 500–530°C when properly designed and operated within its temperature limits. For applications demanding higher creep resistance above 530°C or extended service life beyond 200,000 hours, higher-alloyed grades such as 13CrMo4-5 or 10CrMo9-10 are recommended
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