Mechanical and Metallurgical Characterization of HSLA X70Welded Pipeline Steel Subjected to Successive Repairs

Type : Publication
Auteur(s) :  Bouzid MAAMACHE, Mabrouk BOUABDALLAH, Abdelhalim Brahimi, Youcef Yahmi, Billel CHENITI, Brahim MEHDI
Année :  2016
Domaine : Sciences des matériaux
Revue : Acta Metallurgica Sinica ( English letters)
Résumé en PDF :  (résumé en pdf)
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Mots clés :  HSLA X70 steel; Successive weld repair; Heat affected zone; Dislocation density

Résumé : 

The aim of this work is to study the influence of successive weld repairs on the microstructure and themechanical behavior of the heat-affected zone (HAZ) of an HSLA X70 steel. Detailed microstructural examinationcombined to grain size measurement showed that beyond the second weld repair, the microstructure of the HAZ undergoessignificant change in the grain morphology and grain growth. The results of the X-ray diffraction analyzed using MAUDsoftware indicated an increase in the crystallite size and a decrease in the dislocation density according to the number ofweld repair operations. Consequently, a loss of mechanical properties, namely the yield strength and the toughness with thenumber of weld repairs, was recorded. Beyond the second weld repair operation, the properties of the welded joint do notfulfill the standards applied in piping industry.