SiO2 and CaF2 Behavior During Shielded Metal Arc Welding and Their Effect on Slag Detachability of the CaO-CaF2-SiO2 Type ENiCrFe-7-Covered Electrode

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• 作者：Huang Wang ; Renyao Qin ; Guo He
• 刊名：Metallurgical and Materials Transactions A
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：47
• 期：9
• 页码：4530-4542
• 全文大小：4,195 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Materials Science
  Metallic Materials
  Structural Materials
  Physical Chemistry
  Ceramics,Glass,Composites,Natural Materials
  
• 出版者：Springer Boston
• ISSN：1543-1940
• 卷排序：47

文摘

The metallurgical behavior during shielded metal arc welding (SMAW) and the slag detachability of the CaO-CaF₂-SiO₂ type ENiCrFe-7-covered electrodes was investigated. The results indicated that the slag detachability could be improved as the SiO₂ in the flux coatings decreased. When the SiO₂ in the flux coating was 10.9 pct, about 28.3 pct CaF₂ resulted in the best slag detachability. The CaF₂ and SiO₂ in the flux coating interacted during SMAW to form gaseous SiF₄ to be evacuated. In the reactions, one SiO₂ consumed two CaF₂, leading to the reduction of the ratio of CaF₂/SiO₂. After comparing the slag compositions, the best slag detachability was obtained at CaO:CaF₂:SiO₂ = 1.7:1.8:1, but the worst slag detachability appeared at CaO:CaF₂:SiO₂ = 1.3:0.9:1. The XRD analysis revealed that the oxides and fluorides in the slags preferred to gather together to form cuspidine and other complex phases. If the CaF₂ was dominant in the slags, they intended to form homogenous porous microstructures that were relatively strong and would most likely detach from the weld metal in blocks, exhibiting good slag detachability. If the cuspidine phase was dominant, the slags exhibited a ‘rock strata’-like microstructure in the intergranular area. Such microstructure was very fragile and could be broken into fine powders that were easily embedded in the weld ripples, leading to slag adhesions. This work provides the researcher with a wealth of information and data, which will also be beneficial to the welding material producers and users.Manuscript submitted November 23, 2014.