FRACTURE BEHAVIOR OF THE HEAT AFFECTED ZONE IN 5% NI STEEL WELDMENTS

The fracture properties of the base metal and the heat affected zone (HAZ) of 5% Ni steel weldments were determined at room temperature, 111k and 76K; emphasis was placed on tests at 111K, the minimum boiling point of liquefied natural gas (LNG). The 32 mm-thick test plates, which met the requirements of ASTM A645, were welded using the pulsed-power gas-metal-arc process at a heat input of 10.6 kJ/cm. The fatigue crack growth rates were determined for cracks growing through the thickness using four-point bend specimens. At 111K, the rates in the base metal were essentially the same as found by other investigators, however, the rates in the HAZ were up to 10 times faster than previously reported. Fracture toughness tests were conducted under load-controlled conditions using J-integral procedures. At 111K, the base metal and HAZ toughness values were 30 and 50 percent lower, respectively, than toughness values obtained previously for the same plate of test material under displacement-controlled conditions. Fracture mechanics analyses using the results reported herein indicate that 5% Ni steel is suitable for LNG applications, but more conservative estimates of fatigue life and critical crack size are necessary.

  • Supplemental Notes:
    • Sponsored in part by Maritime Administration, Washington, D.C. Pub. in Weld. J. Res. Suppl., 9p Apr 77.
  • Corporate Authors:

    National Bureau of Standards

    14th Between E Street and Constitution Avenue, NW
    Washington, DC  USA  20234

    Maritime Administration

    1200 New Jersey Avenue, SE
    Washington, DC  USA  20590
  • Authors:
    • McHenry, H
    • Reed, R P
  • Publication Date: 1977-4

Media Info

  • Pagination: 9 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00168787
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: Final Rpt.
  • Files: TRIS, USDOT
  • Created Date: Dec 27 1978 12:00AM