Article
Engineering, Chemical
Jin Zhang, Jun Fan, Dan Zhang
Summary: The purpose of this study is to investigate the transfer behavior of oxygen during the submerged arc welding process using CaF2-SiO2-CaO fluxes. This study introduces two new parameters to quantify the oxygen transfer in specific regions and analyzes the transfer behavior using typical models. The results show that the Multi-Zone model is more accurate in predicting the oxygen content in the metal compared to the equilibrium model. The article provides valuable insights and practical guidance for flux design.
Article
Materials Science, Ceramics
Zhanjun Wang, Xiaorui Zheng, Ming Zhong, Zushu Li, Cong Wang
Summary: This study systematically investigated the crystallization behaviors of CaF2-TiO2 fluxes with varying TiO2 contents. It was found that the TiO2 content of 30 wt.% exhibited the highest barrier to crystallize and the highest capability to achieve the most desired production of amorphous welding fluxes for high heat input applications.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2022)
Article
Engineering, Chemical
Jin Zhang, Qiong Xu
Summary: This study investigates the element transfer behavior of Cr2O3-bearing agglomerated fluxes in submerged arc welding. The gas-slag-metal equilibrium consideration is shown to qualitatively analyze the transfer behaviors, and a thermodynamic approach to predict element transfer levels is proposed.
Article
Green & Sustainable Science & Technology
Zhanjun Wang, Xiaorui Zheng, Ming Zhong, Somnath Basu, Cong Wang
Summary: The crystallization behaviors of CaF2-SiO2 fluxes with different SiO2 contents were studied using SHTT, XRD, and SEM. It was found that increasing SiO2 content led to higher crystallization temperature and shorter crystallization incubation time. The primary crystalline phase changed from CaO to Ca2SiO4 to Ca4Si2O7F2 with increasing SiO2 content. The growth patterns of Ca2SiO4 and Ca4Si2O7F2 crystals were one-dimensional and three-dimensional, respectively. The effective activation energy for the crystalline process decreased with higher SiO2 content, and avoiding Ca4Si2O7F2 phase was recommended for better slag detachability.
JOURNAL OF SUSTAINABLE METALLURGY
(2023)
Article
Materials Science, Multidisciplinary
Xiaobo Yuan, Yongwu Wu, Ming Zhong, Somnath Basu, Zhanjun Wang, Cong Wang
Summary: This study investigated inclusions in EH36 shipbuilding steel submerged arc welded with CaF2-TiO2 fluxes. The inclusions were found to be mainly of a complex Ti-containing type, with an increase in Ti content and a reduction in Al and Mn content with increasing TiO2 content. The size distribution of inclusions followed a log-normal pattern, with frequency peaks ranging from 0.3 to 0.4 μm. The number density and volume fraction of inclusions showed a definite increasing trend, which was attributed to the uptake of O from 110 to 210 ppm enabled by TiO2 decomposition.
SCIENCE AND TECHNOLOGY OF WELDING AND JOINING
(2022)
Article
Engineering, Chemical
Dan Zhang, Guoyou Shao, Jin Zhang, Zhongqiu Liu
Summary: This study investigates the moving behavior of the Neutral Point in submerged arc welding process and proposes a novel thermodynamic approach to detect the movement direction of Mn. The findings suggest that the traditional scientific hypothesis about the Neutral Point may need revision under high heat input welding. The proposed method has the potential to guide flux design and welding parameter setting.
Article
Engineering, Chemical
Dan Zhang, Jin Zhang, Shuchen Yang, Guoyou Shao, Zhongqiu Liu
Summary: This study investigates the effect of SiO2 level in agglomerated fluxes on the element transfer behavior and proposes a thermodynamic method to predict flux O potential and weld metal composition. It provides insights into the gas-slag-metal equilibrium and reveals the limitations of the existing basicity index model for flux O potential prediction.
Article
Chemistry, Physical
Lochan Sharma, Rahul Chhibber
Summary: In this study, wettability and contact angle measurement of twenty-one SAW fluxes for CaO-SiO2-TiO2 & Al2O3-CaO-SiO2 welding flux system at 1300 degrees C were investigated. The purity of flux constituents was determined using XRF technique. The experimental results showed that the contact angle increased with the increase of TiO2/SiO2 ratio, with a higher value observed in a specific composition range.
Article
Materials Science, Multidisciplinary
Zhanjun Wang, Yuyang Liu, Ming Zhong, Zushu Li, Cong Wang
Summary: Bubble evolution behaviors have been thoroughly documented in the solidified slags detached from EH36 shipbuilding steel weld metals processed by CaO-Al2O3-SiO2-CaF2 fluxes. The decrease in CaF2 content leads to a decrease in bubble retention tendency, mainly caused by the disappearance of fluorite and cuspidine and the formation of amorphous phases.
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Xufeng Wang, Fangfang Li, Qiangqiang Wang, Xubin Zhang, Shengping He
Summary: The dissolution behavior of AlN in three CaO-Al2O3-BaO-CaF2-Li2O non-reactive mold fluxes was studied, and the interfaces between the fluxes and AlN were analyzed. The results showed that the width of the element transition layer differed depending on the fluxes, and the fluxes in contact with AlN exhibited stronger reactivity towards AlN.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Multidisciplinary
Yanyun Zhang, Haoxin Liu, Theresa Coetsee, Zhanjun Wang, Cong Wang
Summary: Fluxes of CaF2-SiO2-CaO-TiO2 were designed and used in submerged arc welding of EH36 shipbuilding steel. The pathways for oxygen gain and loss in the weld metal were quantitatively evaluated. The results showed that oxygen gain and loss increased with higher TiO2 content, with oxygen gain slightly exceeding oxygen loss, resulting in a net increase in oxygen in the weld metal. These findings provide a refined strategy for formulating fluxes with lower oxygen potential.
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
(2023)
Article
Metallurgy & Metallurgical Engineering
Ming Zhong, Da-ming Guo, Somnath Basu, Cong Wang
Summary: Fused ternary CaF2-SiO2-MnO fluxes were used to weld EH36 shipbuilding steel with high heat input submerged arc welding. The effect of MnO content on the impact toughness of the weld metal was studied by designing five fluxes with MnO content ranging from 10 to 50 wt.% at the expense of CaF2. An increase in MnO content initially increased and then decreased the Charpy impact energy, reaching a maximum value at 30 wt.% MnO. The microstructure analysis revealed that the highest acicular ferrite volume fraction in the weld metal was achieved at 30 wt.% MnO, which coincided with the maximum Charpy impact energy. The variations in Mn and O content in the weld metal are believed to contribute synergistically to this interesting phenomenon.
JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
Yanyun Zhang, Hang Yuan, Huiyu Tian, Zhanjun Wang, Cong Wang
Summary: The total electrical conductivity of CaF2-SiO2-CaO-TiO2 welding fluxes was studied using the four-electrode method, and the underlying conductive mechanisms were clarified. The contribution of electronic/ionic conductivity to the total electrical conductivity was quantified using the stepped potential chronoamperometry method. The results showed that both electronic and ionic conductivity of the fluxes increased with higher temperature, indicating a thermally activated process.
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Ming Zhong, Tao Li, Somnath Basu, Zhanjun Wang, Cong Wang
Summary: The transfer behavior of phosphorus in submerged arc welding of EH36 shipbuilding steel with CaF2-TiO2-CaO fluxes has been systematically investigated. It was found that dephosphorization can be induced with a CaO content higher than 15.7 mass pct, while phosphorus uptake may occur otherwise. The major driving force enabling phosphorus transfer is largely governed by the activity difference between hypothetical P2O5 in the flux and that equilibrated with the weld metal.
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
(2022)
Article
Materials Science, Ceramics
Jin Zhang, Li Wang
Summary: Fluxes play important roles in atmospheric shielding, arc stabilization, and weld metal composition control during submerged arc welding process. Mn content control is critical for weldment toughness. This study aims to upgrade the slag-metal equilibrium model to the gas-slag-metal equilibrium model using CALPHAD technology to compensate for the limitations of the former. Both slag-metal and gas-slag-metal equilibrium models were used to predict Mn content in weld metal. The gas-slag-metal equilibrium model showed higher prediction accuracy and the capability to predict Mn transfer even without initial MnO.
CERAMICS INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
T. Coetsee, R. J. Mostert, P. G. H. Pistorius, P. C. Pistorius
Summary: The study analyzed the effects of different commercial flux compositions in Submerged Arc Welding (SAW), emphasizing the importance of the gas phase in element transfer. By improving the accuracy of predicted weld metal oxygen values through modeling, it is expected to reduce the number of welding tests required to develop new flux formulations.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Materials Science, Multidisciplinary
Jin Zhang, Cong Wang, Theresa Coetsee
Summary: Different models were utilized to predict weld metal compositions, with the basicity index model showing capability in predicting trends of oxygen content but inability to differentiate oxygen levels under the same basicity index. The slag-metal model overestimated silicon and manganese contents, while the gas-slag-metal equilibrium model showed better accuracy in predicting oxygen content and differentiation for fluxes with varying formulas.
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
(2021)
Article
Metallurgy & Metallurgical Engineering
Theresa Coetsee, Frederik Johannes De Bruin
Summary: The combination of Al powder and Ti powder can increase the transfer of Ti into the weld metal while maintaining high oxygen content for inclusion formation. Oxide inclusions in the weld metal serve as possible nucleation sites for acicular ferrite formation, enhancing weld metal strength and toughness.
MINERAL PROCESSING AND EXTRACTIVE METALLURGY REVIEW
(2022)
Article
Engineering, Chemical
Theresa Coetsee, Frederik De Bruin
Summary: In submerged arc welding of chromium containing steels, sourcing chromium from weld wire is costly, and alloying with high levels of copper is hindered by work hardening of the weld wire. This study explores the use of copper as a stabilizer, in conjunction with aluminum, to enhance chromium transfer to the weld pool. The application of aluminum powder is confirmed to control the oxygen pressure and maintain the acceptable oxygen content in the weld metal.
Article
Geochemistry & Geophysics
Theresa Coetsee, Frederik De Bruin
Summary: Flux formulations are used to control chemical and physico-chemical parameters to ensure weld quality. This study found that it was difficult to detach the slag in welds made with metal powder additions. Modifying the flux formulation by increasing the CaF2 content can improve slag properties.
Article
Chemistry, Multidisciplinary
Theresa Coetsee, Frederik De Bruin
Summary: Nickel alloying of carbon steel can enhance its strength and toughness. The use of aluminum powder and nickel powder to alloy the weld metal simplifies the process and increases the yield of nickel, without the need for expensive and time-consuming manufacturing of alloyed wire and alloyed powder.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Chemical
Theresa Coetsee, Frederik De Bruin
Summary: Al-Cr-Ti-Cu unconstrained metal powders are used to assist the alloying of carbon steel in Submerged Arc Welding (SAW). The addition of Al-Cu-Ti and Al-Cu-Ti-Cr metal powders increases the metal deposition rates by 19% and 40% respectively, compared to the base case without metal powder additions. Using Al powder as a deoxidiser allows for control of oxygen partial pressure and ensures the transfer of Ti and Cr metal powder into the weld pool while keeping the oxygen content in acceptable limits. The likely sequence of alloy melt formation is deduced from the alloy phase diagrams and the effect of Fe addition is illustrated in thermochemical calculations.
Article
Geochemistry & Geophysics
Theresa Coetsee, Frederik De Bruin
Summary: Chromium alloying in weld metal is typically achieved through the use of weld wire. This is because chromium has a strong affinity for oxygen and is not easily transferred across the arc. The study investigates the chemical behavior of chromium in the application of unconstrained metal powders in submerged arc welding (SAW). It was found that the addition of aluminum in SAW helps control the oxygen partial pressure to prevent oxidation of elements like chromium. The speciation of chromium was observed in post-weld slag samples, showing distinct chromium spots in the oxy-fluoride dome walls and chromium-rich particles.
Article
Chemistry, Multidisciplinary
Theresa Coetsee, Frederik De Bruin
Summary: This study demonstrates the application of unconstrained cobalt and aluminium powders in Submerged Arc Welding to alloy weld metal and control oxygen content. By adding aluminium powder, a 70% yield of Cobalt was achieved in the weld metal, while total oxygen content was controlled to 230 ppm.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Chemical
Theresa Coetsee, Frederik De Bruin
Summary: Using unconstrained metal powders of chromium, nickel, and aluminium in submerged arc welding can simplify the alloying process, enhance the yields of Cr and Ni, and contribute to overall productivity gains in the welding process.
Article
Engineering, Chemical
Theresa Coetsee, Frederik De Bruin
Summary: The use of aluminium metal powder in submerged arc welding processes has been shown to effectively modify the flux oxygen behaviour, resulting in decreased oxygen content in the weld metal and minimized loss of chromium and cobalt to the slag. The addition of aluminium powder lowers the partial oxygen pressure in the arc cavity and at the molten flux-weld pool interface, preventing oxidation of these metals. This novel application of aluminium powder in SAW demonstrates its potential to improve the welding process and reduce metal loss.
Article
Engineering, Chemical
Theresa Coetsee, Frederik De Bruin
Summary: The chemical behavior of copper in submerged arc welding (SAW) was studied, and it was found that the addition of copper can stabilize the welding process by forming an alloy melt with aluminum, reducing the melting temperature of high-melting-point metals. The actual vaporization quantity of copper in welding is higher than the calculated quantity in thermochemical equilibrium, possibly due to the condensation of vaporized copper and the effect of surface-active elements.
Article
Engineering, Chemical
Theresa Coetsee, Frederik De Bruin
Summary: This study demonstrates the successful application of aluminium as a de-oxidiser in submerged arc welding. By preventing oxidation of certain elements, it helps to reduce element loss and improve the overall welding process. The inclusion of aluminium in the arc cavity effectively lowers the partial oxygen pressure and decreases the total oxygen content in the weld metal.
Review
Engineering, Chemical
Theresa Coetsee, Frederik De Bruin
Summary: This review focuses on the thermochemical behavior of fluxes in submerged arc welding (SAW) and reviews English-language literature from the 1970s onwards. It explains the link between flux-induced oxygen potential and element transfer but also highlights the importance of considering the gas phase for accurate SAW process metallurgy equilibrium calculations. Recent works on the application of Al metal powder with alloying metal powders provide new insights into gas phase reactions in the SAW process and the modification of flux oxygen behavior via Al additions.
Article
Engineering, Chemical
Theresa Coetsee, Frederik De Bruin
Summary: The aim of this study is to improve the understanding of the SAW process and provide a better description of the gas-slag-metal reactions with alloy powder and Al powder additions. The addition of aluminium as a de-oxidizer effectively reduces the oxygen partial pressure in the process, preventing oxidation of chromium and reducing the total oxygen content in the weld metal. The results demonstrate the importance of considering gas phase reactions in the interpretation and modeling of SAW process metallurgy. Rating: 8/10.
