Accelerated Microstructure Transformation Caused by Thermal-Mechanical Fatigue

Abstract:

Thermal mechanical fatigue (TMF) was found to accelerate microstructure transformation in martensitic-bainitic Cr-Mo-V creep-resisting steels used in power generation. Particular role in this acceleration has been ascribed as being due to configurations of dislocations generated in the compression part of the TMF cycle, which dislocations in the tensile part of the cycle appeared to assist precipitation processes while important role in this acceleration is due to Bauschinger effect. Based on this finding an accelerated creep test (ACT) on Gleeble thermal mechanical simulator was developed to gain in a short time of less than 30 hours the microstructures and properties of steels and welds similar to these appearing after the long-term exposure in power plants. Investigations by scanning electron microscopy and transmission electron microscopy confirmed similarity of microstructure transformation after the ACT with this occurring after the multi-year real creep in power generating installations, in particular in these where premature failures occurred.

• Periodical: Materials Science Forum (Volumes 706-709)
• Pages: 871-877
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.706-709.871
• Online since: January 2012
• Authors: Stan T. Mandziej
• Keywords: Creep, Dislocation, Electron Microscopy, Fatigue

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