PREDICTION OF HYDROGEN CRACKING IN MULTIPASS WELDS IN LOW CARBON STEELS

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Authors
  1. Graville, B.A.
  2. Pussegoda, L.N.
  3. Malik, L.
Corporate Authors
Graville Associates Inc, Georgetown ONT (CAN);Defence Research Establishment Atlantic, Dartmouth NS (CAN)
Abstract
Enormous advances have been made in recent years to improve the hydrogen cracking resistance of steels during welding by using low carbon levels coupled with thermo-mechanical controlled processing, precipitation hardening, or other strengthening methods. As the resistance to heat affected zone cracking has improved, however, the region of greatest risk of cracking has shifted from the HAZ to the weld metal, or as experienced in pipelines, the reheated HAZ of multipass welds. Whereas the critical problem with older steels was the determination of a suitable perheat to allow the root pass to be deposited wihtout HAZ cracking, with modern steels the challenge is to determine welding procedures, that prevent critical hydrogen levels being reached at any critical location throughout a multipass weld. The initial preheat may be less important than, say, the number and size of passes, the geometry of the weld, or the time/temperature experience between passes. Time between passes is rarely specified in a welding procedure but may have a decisive effect on local hydrogen concentrations and the risk or weld metal cracking. In the present work, hydrogen distribution is modelled using a simple finite difference approach that accounts for the major factors influencing hydrogen levels. TRUNCATED
Report Number
DREA-NAMT-95-6-PAP-6 — CONTAINED IN 99-00779
Date of publication
30 May 1995
Number of Pages
13
DSTKIM No
99-00811
CANDIS No
510375
Format(s):
Hardcopy;Document Image stored on Optical Disk

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