PSI - Issue 60

A. Bhardwaj et al. / Procedia Structural Integrity 60 (2024) 723–734 Abhimanyu Bhardwaj/ Structural Integrity Procedia 00 (2019) 000 – 000

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3.5. Fatigue and creep analysis In Section 3.2 and 3.3, it is demonstrated that the job carrier experiences no plastic strain as stress values are well below the yield stress, indicating the absence of fatigue failure as well. Therefore, the determined life of the job-carrier is infinite, signifying that it will not experience fatigue failure under these operational conditions However, it is important to acknowledge that the practical life of the job-carrier is ultimately tied to the furnace life, limited to 1000 cycles in this particular case. Creep is characterized as the time-dependent behavior of a material that experiences permanent deformation below its yield point when subjected to continuous stress. The creep temperature range for the TZM alloy starts at 1200 deg C. In this specific case, the job-carrier operate within a maximum temperature range of 1100 deg C, while for the majority of the time, it functions at temperatures below this threshold. Therefore, within the scope of this work, the creep analysis and creep-fatigue interaction analyses is not required. 4. Development and In-Service Trials Based on the preceding studies and analyses, an engineering design of the job carrier was meticulously prepared, followed by the development of its complete assembly. Initially, the assembly was placed inside the furnace without any external load and subjected to a controlled temperature cycle up to 1100 deg C with ramp rate of 10 deg C /min and hold time of 60 min at the maximum temperature. Subsequently, a comparable cycle was also performed with the job-carrier under loaded conditions, as illustrated in Fig. 12. Under both circumstances, the job carrier's structural integrity remained uncompromised, as no discernible deformations were observed.

Fig. 12 TZM alloy job-carrier loaded with jobs inside the furnace.

5. Conclusion In conclusion, the use of TZM alloy as the material of construction for the job-carrier proves to be a sound decision, considering its exceptional properties. These attributes make it a highly suitable choice for job-carrier for the various furnaces operating in this particular temperature range. The manufacturing processes of TZM alloy, present challenges when it comes to welding, leading to the adoption of standard structural components like U-rails