Title: Correlation of microstructure and hardness of two-pass submerged arc welds of line pipe steel X65

Authors: Rrahim Maksuti, Hamit Mehmeti, Shefik Imeri

Addresses: Faculty of Mining and Metallurgy, University of Prishtina, Parku Industrial-Trepca, p.n., Mitrovica-Kosova. ' Faculty of Mining and Metallurgy, University of Prishtina, Parku Industrial-Trepca, p.n., Mitrovica-Kosova. ' NewCo Ferronickeli Complex L.L.C., Ferronikeli p.n., Drenas, Kosova

Abstract: The integrity and performance of the welded joint of line pipe depend on the microstructure and associated properties. Fusion welding may be considered as a miniature casting, but because the heating temperature is higher and cooling very quickly, the final microstructure of a weld and a casting are both dendritic, but the differences are greater than the similarities. The microstructure of the two pass weld is generally non-uniform, being composed of areas of as deposited weld metal and areas that have been reheated by subsequent pass and hence has pronounced effect on the mechanical properties. The obtained results using LOM (light optical microscopy), SEM (scanning electron microscopy) and hardness testing are presented in this work and this is an attempt to establish a correlation between microstructure and hardness of two-pass submerged arc welds of line pipe steel X65 according to API (American Petroleum Institute).

Keywords: microstructure; submerged arc welding; welds; hardness; line pipes; welded joints; line pipe steel.

DOI: 10.1504/IJMMP.2009.031140

International Journal of Microstructure and Materials Properties, 2009 Vol.4 No.3, pp.347 - 355

Published online: 21 Jan 2010 *

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