Effect of E8010-P1 electrode composition on the weld metal properties M. Mosallaee * , J. Hydari, S. Ghassemy, A. Mashreghee Department of Mining and Metallurgy, Yazd University, Yazd, Iran article info Article history: Received 25 November 2012 Received in revised form 17 May 2013 Accepted 22 May 2013 Keywords: E8010-P1 Welding Pipe line Ferrite Microstructure abstract Different manufactures produce E8010-P1 electrode with different chemical compositions due to the relatively wide range of permissible alloying elements in the composition of this electrode. Four groups of E8010-P1 electrodes, with different compositions, were selected and effect of electrode composition on the microstructure and mechanical properties of weld meal were examined. Microstructural studies revealed that presence of the Mn, Mo and Ni in the weld metal influences significantly on the morphology of ferrite in the weld metal zone. Large amount of Mn (around 1%) in the weld metal leads to the formation of fine acicular ferrite in the weld metal. Furthermore, presence of Mo (around 0.4%) in the weld metal prevents formation of continuous grain boundary ferrite in the weld zone. Mechanical properties investigations reveal that the more acicular ferrite in the weld metal, the higher strength and ductility of this zone. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Pipe line is the best economical way for transferring various fluids such as crude oil, natural gas or their products. The pipe line base metals must have high strength to be able for transferring high pressure fluid in long distance. Therefore, high strength steel grades of 70 or 80 are mostly used for pipelines [1]. One of the critical sections of pipelines is their welded area, i.e. any weld de- fects or deterioration of mechanical properties in the welding area results in inefficiency of the whole pipelines. Unique characteristics of shielded metal arc welding (SMAW) introduce this process as the best candidate for pipelines welding [2]. E8010-P1 and E7010-P1 electrodes are the most used cellulosic electrodes in the pipelines welding. According to AWS A5.5, rela- tively wide range of elements is allowed for chemical composition of these electrodes (Table 1) [3]. Therefore, different electrode manufacturers produce cellulosic electrodes according to their specific formulation that are slightly different from other manu- facturer products. Ni, Mo and Mn are the most effective elements in the compo- sition of cellulosic electrodes. These elements have significant ef- fect on the microstructure and mechanical properties of deposited weld metal [4,5]. Evans and Bailey’s research [6] reveals that for- mation of acicular ferrite (AF) in the weld metal has effective influence on the mechanical properties of weld metal. Some re- searchers reported that increasing of Mn contents in the weld metal increased the amount of AF and reduced the polygonal ferrite (PGF) and side plate ferrite (SPF) in the weld metal [7,8]. Taylor and Evans [9] showed that increasing the level of Ni in the weld metal reduces the amount of grain boundary ferrite (GBF) and refines the AF in the weld metal. It was reported that increasing of Mo in the composi- tion of weld metal leads to increasing of AF in weld metal [10,11]. Experimental investigation of Shanmugam et al. [12] showed that unlike AF, formation of GBF and upper bainite in the weld metal reduced the toughness of welded sample. Due to the significant effect of weld metal composition on the characteristics of pipe line weld metal and because of relatively wide range of permissible alloying elements in composition of cellulosic electrodes, four different E-8010-P1 cellulosic electrodes were selected and relation between the electrode composition and weld metal structure and mechanical properties were evaluated. 2. Experimental procedure Four different cellulosic electrodes that all were in the E8010-P1 classification were selected and subjected the shielded metal arc welding (SMAW) according to their standard welding procedure. Tables 2 and 3 exhibit the chemical compositions and welding conditions of these electrodes, respectively. Chemical composition of weld metals was determined accord- ing to AWS A5.5 i.e. samples with six layers welding and three passes in each layer were welded and chemical composition of each * Corresponding author. Tel.: þ98 351 8122602, þ98 913 1534854. E-mail address: mosal@yazd.ac.ir (M. Mosallaee). Contents lists available at SciVerse ScienceDirect International Journal of Pressure Vessels and Piping journal homepage: www.elsevier.com/locate/ijpvp 0308-0161/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijpvp.2013.05.004 International Journal of Pressure Vessels and Piping 111-112 (2013) 75e81