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Metallurgical failure analysis of cast hk40 steel u-clamp: role of shrinkage-related porosity

Pouranvari, M ; Sharif University of Technology | 2023

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  1. Type of Document: Article
  2. DOI: 10.1007/s11668-022-01583-7
  3. Publisher: Springer , 2023
  4. Abstract:
  5. This paper investigates the metallurgical factors that contributed to the failure of several cast U-clamps made of HK40 steel U-clamps during the installation of a pre-startup heater in a petrochemical plant. The presence of extensive macro/micro-shrinkage porosity is identified as the root cause of the failure. The severe shrinkage-related porosity in the material, confirmed by metallographic examination and non-destructive X-ray radiography testing and evidenced by a severe loss in tensile ductility, resulted in a unique fully dendritic fracture surface characteristic. It was found that the loss of structural integrity associated with macro-shrinkage voids and loss of toughness associated with microporosity led to premature failure of U-clamps when subjected to bending forces during installation. The casting process should be designed to guarantee a higher Niyama criterion value, defined as the local thermal gradient divided by the square root of the local cooling rate, in the casting to produce a sound U-clamp. © 2022, ASM International
  6. Keywords:
  7. Failure ; HK40 ; Macroporosity ; Microporosity ; Shrinkage-related defect ; U-clamp
  8. Source: Journal of Failure Analysis and Prevention ; Volume 23, Issue 1 , 2023 , Pages 306-313 ; 15477029 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s11668-022-01583-7