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Grain Boundary Engineering to Control the Intergranular Stress Corrosion Cracking of Pipeline Steel
Last modified: 2013-05-03
Abstract
The roles of grain boundary character and crystallographic texture on intergranular stress corrosion cracking (IGSCC) of API-X65 pipeline steel have been studied using Electron Backscattered Diffraction (EBSD) and X-Ray texture measurements with an ultimate objective to engineer the structure of grain boundaries to avoid such cracking.
It has been found that low-angle and special coincident site lattice (CSL) boundaries (mainly, Σ11 and Σ13b) are crack-resistant while the random high-angle boundaries are prone to cracking. However, several cracks were found to have been arrested even when random high-angle boundaries were available for them to continue propagating. Texture analyses revealed that {110}//RP and {111}//RP textured grains, mainly associated with <110> and <111> boundary rotation axes, respectively, were dominant in the vicinities of these crack-arrest points while the cracked boundaries were mainly linked to the {100}//RP textured grains. Controlled thermo-mechanical treatment could be utilized to produce these crack-resistant boundaries
It has been found that low-angle and special coincident site lattice (CSL) boundaries (mainly, Σ11 and Σ13b) are crack-resistant while the random high-angle boundaries are prone to cracking. However, several cracks were found to have been arrested even when random high-angle boundaries were available for them to continue propagating. Texture analyses revealed that {110}//RP and {111}//RP textured grains, mainly associated with <110> and <111> boundary rotation axes, respectively, were dominant in the vicinities of these crack-arrest points while the cracked boundaries were mainly linked to the {100}//RP textured grains. Controlled thermo-mechanical treatment could be utilized to produce these crack-resistant boundaries
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