Influence of Melting Practice and Heat Treatment on the Continuous Cycling Fatigue and Subcritical Crack Growth Properties of 2 1/4 Cr-1 Mo Steel

Technical Report · Tue May 01 00:00:00 EDT 1979

DOI:https://doi.org/10.2172/6127027· OSTI ID:6127027

Strizak, J. P. ^[1]; Brinkman, C. R. ^[1]

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1. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Metals and Ceramics Div.

Interim results are reported for continuous cycling strain-controlled fatigue and fatigue crack growth tests of 2 1/4 Cr-1 Mo steel. Heat-to-heat variations due to different melting practices and postweld heat treatment of annealed and isothermally annealed material were considered. Apparently, continuous cycle fatigue behavior at 427 and 538°C did not differ among the heats manufactured by air-melt, vacuum-arc remelt, and electro-slag remelt practices. Furthermore, a possible postweld heat treatment of 40 h at 726°C on initially annealed or isothermally annealed material did not influence continuous cycle fatigue life. Interim fatigue crack growth rate results at 510°C extended data to higher stress intensity levels. Fatigue crack growth rate data for isothermally annealed air-melt material obtained at frequencies of 0.067_ and 0.67 Hz over a stress intensity range of 30 to 60 √MPa agreed well with previous results not exceeding 40 √MPa s/m. Cyclic life tests using both hourglass-shaped and uniform-gage specimens were compared. The 5.08-mm-diam hourglass-shaped specimen had a lower fatigue life than the 6.35-mm specimen. The discrepancy in the results for these two hourglass-shaped specimens decreases with decreasing total axial strain range. Furthermore, the uniform-gage specimen had a lower fatigue life than the 6.35-mm-diam hourglass-shaped specimen.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-00OR22725; W-7405-ENG-26
• OSTI ID: 6127027
• Report Number(s): ORNL/TM--6782
• Country of Publication: United States
• Language: English

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