THE INFLUENCE OF WELD STRENGTH MISMATCH ON THE FITNESS-FOR-SERVICE OF HIGH STRENGTH STEEL STRUCTURES

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Authors
  1. Kirk, M.T.
Corporate Authors
Edison Welding Inst, Columbus OH (US);Defence Research Establishment Atlantic, Dartmouth NS (CAN)
Abstract
In welded construction, the solidified metal and surrounding region (heat affected zone, or HAZ) have fracture toughness that is characteristically lower and less well controlled than that of the base material joined due to inferior metallurgical quality of the metal in the weld region (Kerr, 1976). Further, welding produces defects which must be considered to insure structural integrity against fracture. Taken together, the low fracture toughness and high defect probability characteristic of weldments provide incentive to prevent large deformation in welded regions. For this reason, many codes require use of weld metals whose strength exceeds that of the plates jointed (ASME, 1980; AWS, 1980; USDOT, 1979); a practice referred to as overmatching. Overmatched welds generally force plastic deformation into the lower strength plate (Denys, 1990) where better fracture resistance and fewer defects are expected. Unfortuneately, overmatching weld metal strength has economic and technical disadvantages which undermatched (weld metal yield strength less than plate yield strength) construction might alleviate. For example, welding of high strength steels requires preheat to prevent hydrogen cracking. Satoh and co-workers (1978) demonstrated that preheat requirements could be halved by switching to undermatched construction. TRUNCATED
Report Number
DREA-NAMT-93-4-PAP-14 — CONTAINED IN 99-00578
Date of publication
30 Apr 1993
Number of Pages
3
DSTKIM No
99-00592
CANDIS No
510319
Format(s):
Hardcopy;Document Image stored on Optical Disk

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