Masters Theses

Date of Award

8-2012

Degree Type

Thesis

Degree Name

Master of Arts

Major

Materials Science and Engineering

Major Professor

Carl D. Lundin

Committee Members

Carl J. McHargue, John D. Landes

Abstract

Several fabricators have recently noted the occurrence of reheat cracking in the weld deposits of 2¼[ two and one fourth]Cr‑1Mo‑¼[one fourth]V (22V) during the fabrication of pressure vessels used in the petrochemical industry. Due to increased oversight now required during fabrication of already expensive pressure vessels, studies have commenced worldwide in an effort to identify root causes and formulate mitigating actions to weld reheat cracking issues. The Materials Joining Group (MJG) at the University of Tennessee at Knoxville (UTK) have adapted an existing reheat cracking test originally developed for use with alloys similar to 22V. This original C‑Ring test was used successfully, and as such, has set the foundation for the development of the modified C‑Ring discussed in this report. A modified test, the Notched C‑Ring Reheat Cracking Test (NCRRCT) has been developed. The NCRRCT is able to accurately rank 2¼ [two and one fourth]Cr-1Mo-¼[one fourth]V (22V) weld deposits for reheat cracking susceptibility, and in doing so identify 22V weld deposits susceptible to reheat cracking before issues arise during fabrication. The NCRRCT meets all of the attributes of the so-called “Ideal Weldability Test”, in that it shows a direct correlation with actual fabrication, yields reproducible results, highlights small changes in testing variables, clearly demonstrates the effects of welding related variables (i.e., weld design and heat input), is economical, and applies to all welding processes

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