SYMPOSIA PAPER Published: 01 January 1994
STP15194S

Mitigation of Harmful Effects of Welds in Zirconium Alloy Components

Source

Welding produces local residual tensile stresses and changes in texture in components made from zirconium alloys. In the heat-affected zone in tubes or plates, the basal plane normals are rotated into the plane of the component and perpendicular to the direction of the weld. Thin-walled Zircaloy-2 tubes containing an axial weld do not reach their full strength because they always fail prematurely in the weld when pressurized to failure in a fixed-end burst test. Reinforcing the weld by increasing its thickness by 25% moves the failure to the parent metal and improves the biaxial strength of the tube by 20 to 25% and increases the total elongation by 200 to 450%. In components made from Zr-2.5Nb, the texture in the heat-affected zone promotes delayed hydride cracking (DHC) driven by tensile residual stress. Although the texture is not much affected by heat-treatments below 630°C and large grain interaction stresses remain as a result of mixed textures, macro-residual tensile stresses can be relieved by heat treatment to the point where the probability of cracking is very low.

Author Information

Coleman, CE
Atomic Energy of Canada Ltd., AECL Research, Chalk River Laboratories, Chalk River, Ontario, Canada
Doubt, GL
Atomic Energy of Canada Ltd., AECL Research, Chalk River Laboratories, Chalk River, Ontario, Canada
Fong, RWL
Atomic Energy of Canada Ltd., AECL Research, Chalk River Laboratories, Chalk River, Ontario, Canada
Root, JH
Atomic Energy of Canada Ltd., AECL Research, Chalk River Laboratories, Chalk River, Ontario, Canada
Bowden, JW
Atomic Energy of Canada Ltd., AECL Research, Chalk River Laboratories, Chalk River, Ontario, Canada
Sagat, S
Atomic Energy of Canada Ltd., AECL Research, Chalk River Laboratories, Chalk River, Ontario, Canada
Webster, RT
, Scio, Oregon
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Developed by Committee: B10
Pages: 264–284
DOI: 10.1520/STP15194S
ISBN-EB: 978-0-8031-5286-1
ISBN-13: 978-0-8031-2011-2