Structural Roles of TiO 2 in CaF 2 -SiO 2 -CaO-TiO 2 Submerged Arc Welding Fluxes
- PDF / 1,323,806 Bytes
- 6 Pages / 593.972 x 792 pts Page_size
- 7 Downloads / 189 Views
to high efficiency, submerged arc welding (SAW) has been extensively applied in a wide spectrum of engineering settings, such as pressure vessel, oil and gas pipeline, offshore and shipbuilding.[1,2] For SAW operation, welding fluxes are designed to perform essential functions, including protecting the weld pool from oxidation, adding alloying elements to the weld metal (WM), refining weld pool, and improving welding efficacy.[3] As a matter of fact, such functions are enabled, to a large extent, by the physicochemical properties, namely, melting point, viscosity, thermal and electrical conductivity, and activity, of the fluxes, which, in turn, are inherently rooted in the structures.[4–6] Therefore, an illustrated understanding of the
YANYUN ZHANG is with the School of Metallurgy, Northeastern University, Shenyang 110819, China. THERESA COETSEE is with the Department of Materials Science and Metallurgical Engineering, University of Pretoria, Pretoria, 0002, South Africa. HAIFENG YANG is with the Minmetals Yingkou Medium Plate Co., Ltd, Yingkou 115005, China. TAN ZHAO is with the State Key Laboratory of Metal Material for Marine Equipment and Application, Angang Steel Co., Ltd, Anshan 114021, China. CONG WANG is with the School of Metallurgy, Northeastern University and also with the State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China. Contact e-mail: [email protected] Manuscript submitted April 26, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS B
fine structure is of crucial significance for flux designing strategies geared towards various SAW applications. Over the past decades, CaF2-CaO-SiO2 based fused fluxes, owing to satisfactory chemical homogeneity, non-hygroscopic nature, low oxygen potential, and fine arc stability, have been applied for SAW engineering of high strength low alloy (HSLA) steel grades.[2,7,8] Among them, TiO2-bearing variants have also been developed for enhanced slag detachability as well as improved arc stability.[2] On top of these advantages, Ticontaining inclusions introduced into the weld pool via slag-metal reactions can promote the nucleation of acicular ferrites (AF),[9,10] which has been proven to be effective enhancing WM fracture toughness.[1,7] It needs to be pointed out that controversies regarding the structural roles of TiO2 and how Ti is transferred from the flux to the weld metal still persist, as pertinent analysis over flux structure evolution is far from complete.[10–12] Previous TiO2 based studies mainly focused on blast furnace slag and mold slag, and to date, there has been debate about the structural roles of TiO2 in slag. Shon et al.[13] and Shankar et al.[14] studied the effect of TiO2 on the viscosity of CaO-SiO2-MgOAl2O3-TiO2 mold slags, indicating that viscosity decreases with TiO2 addition and TiO2 serves primarily as network-breakers. On the contrary, Zheng et al.[15] showed that TiO2 might be considered as networkformers in CaO-SiO2-TiO2 blast furnace slag system as it enhanced polymerization of the network. However, it needs t
Data Loading...
