![]() SAW is an established manufacturing process with a continuous wire feed and a welding flux which shields the weld pool from the surrounding atmosphere and has numerous functions such as deoxidation, supply of alloying elements and slag formation. For the application in thick walled reactors, the 2.25Cr-1Mo-0.25V steel is commonly joined with submerged-arc welding (SAW) (Ref 5). As these reactors might be operated under creep conditions, the applied 2.25Cr-1Mo-0.25V welding consumables require a beneficial combination of strength and toughness as well as enhanced creep rupture strength (Ref 3, 4, 5, 6). Typical applications are, e.g., hydrocracking and desulfurization reactors, which are exposed to elevated temperatures of 400 to 450 ☌ and high pressures (Ref 4). It is commonly used for reactors in power stations or in petroleum and chemical plants (Ref 1, 2, 3). The alloy 2.25Cr-1Mo-0.25V was developed in the early 90s by combining the properties of 2.25Cr-1Mo-type with the ones of 1CrMoV-type steels. In contrast to the stress rupture time and the toughness, the weld metal’s strength, ductility and macro-hardness remain nearly unaffected by changes of the heat input. This is assumed to be linked to a lower number of weld layers, and therefore, a decreased amount of fine grained reheated zone if the multilayer weld metal is fabricated with higher heat input. Furthermore, it was determined that a higher heat input during SAW causes an increase in the stress rupture time and a decrease in Charpy impact energy. The heat input was found to increase the primary and secondary dendrite spacing as well as the bainitic and prior austenite grain size of the weld metal. This study deals with the influence of the heat input during submerged-arc welding (SAW) on the solidification structure and mechanical properties of 2.25Cr-1Mo-0.25V multilayer metal. The mechanical properties are known to be influenced by several welding parameters. As these reactors are operated at elevated temperatures and high pressures, the 2.25Cr-1Mo-0.25V welding consumables require a beneficial combination of strength and toughness as well as enhanced creep properties. This work provides a novel route for further development of FeSiB alloys with excellent soft magnetism.The alloy 2.25Cr-1Mo-0.25V is commonly used for heavy wall pressure vessels in the petrochemical industry, such as hydrogen reactors. MGSed alloys have better resistance to magnetic field saturation, and their saturated magnetic field Hj value reaches 12,000 Oe, which is more than 3 times that of NGSed alloys. It grows directional parallel to the direction of the magnetic field line, and connects the adjacent primary branches to form a grid-like magnetically guided solidification structure with uniform spacing The soft magnetic properties of the magnetically guided solidified(MGSed) FeSiB alloy are much better than the non-magnetically guided solidified(NGSed) FeSiB alloy, and the maximum permeability (μ m) of MGSed FeSiB alloy is as high as 964.4789, which is twice as much as that of NGSed alloys. At the same time, the secondary branches of the α-Fe (Si) phase dendrites also follow the direction of the magnetic field line. The primary branches of the α-Fe (Si) phase dendrites grow in parallel along the vertical direction of the magnetic field line, and the length of the primary branches reaches more than 1 mm. It shows that the magnetic field has strong guiding and promoting effect on the growth of dendrites. In this paper, the growth of dendrites and its effect on soft magnetic properties of Fe 78Si 13B 9 alloy during solidification under the effect of 0.18 T oriented magnetic field are studied.
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