Analysis of Laser-Metal Active Gas Hybrid Weldments of HSLA-65 Steel – Macroscopic, Microstructural and Hardness Evaluations

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Authors
  1. Munro, C.D.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
Abstract
Butt welds in HSLA-65 steel formed using a hybrid laser-metal active gas (MAG) technique were assessed in terms of weld profile, macrostructure, microstructure, and microhardness. Most processing parameters were consistent from weld to weld, although there were slight variations in welding speed and root gap. The welds were manufactured at the National Research Council Aerospace Manufacturing Technology Centre (NRC-AMTC) for the purpose of developing the welding procedure. Plates of thicknesses up to 9.26 mm were successfully welded with a single pass, although the top of the weld metal was seen to be recessed from the front plate surface and protruding from the back surface. Hybrid welds were more homogeneous when fabricated using a laser-leading configuration, rather than the converse MAG-leading setup. The heat affected zones (HAZs) were, on average, 1.34 mm wide at the centreline of each test plate. Weld metal and a portion of the adjacent HAZ were of a relatively homogenous hardness that varied according to welding speed. Hardness values dropped quickly within the visible HAZ to the level of the base metal. Microstructurally, weld metal consisted of acicular ferrite while the visible HAZ contained a transition from bainite to a homogeneous mixture of ferrite and pearlite at increasing distances from the fusion boundary. The base metal was composed of banded layers of ferrite and pearlite, aligned in the rolling direction.

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Report Number
DRDC-ATLANTIC-TM-2009-257 — Technical Memorandum
Date of publication
01 Feb 2010
Number of Pages
24
DSTKIM No
CA034222
CANDIS No
533655
Format(s):
Electronic Document(PDF)

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