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In the present investigation, wire arc additive manufacturing of Inconel 625 was carried out with the cold metal transfer variant of the metal inert gas process. The heat input varied between 0.46 and 0.63 kJ/mm, which is a rather low heat input with low deposition rate. The built walls were subjected to Charpy V and crack tip opening displacement (CTOD) fracture toughness testing, in addition to microstructure examination with light microscope and scanning and transmission electron microscope. The results obtained show that hardness increases from the base metal level of 210, via the heat-affected zone (in the building plate) with HV of 220, to the weld metal, with a hardness of around 240–250. All individual Charpy V values fall within the range from 160 to 200 J, while the CTOD fracture toughness is within the range from 0.49 to 1.05 mm. The microstructure examination revealed the microsegregation of certain elements to the interdendritic regions, causing three different particle types to form. Particles with a spherical morphology were identified as spinel (MgAl2O4). Some of the spinel particles were surrounded by disc-shaped precipitates, which were identified as (NbTi)(CN), having the same orientation as the spinel. [ABSTRACT FROM AUTHOR]

The addition of electric arc furnace slag and ladle furnace slag on strength improvement of lateritic soil was studied in this work. Liquid limit, plasticity index, and the California bearing ratio of lateritic soil mixed with the slags were determined in comparison to those of ordinary lateritic soil. A scanning electron microscope was used to confirm the effect of those two slags on microstructures related to chemical components of raw materials and the strength of lateritic soil. The deterioration of California bearing ratio, liquid limit, and plastic index values were obtained when the electric arc furnace slag was mixed in lateritic soil. Meanwhile, the California bearing ratio of lateritic soil was highly improved with the addition of ladle furnace slag, owing to the hydration reaction between water and excess lime in ladle furnace slag with free silica in lateritic soil. The values of the plasticity index were also comparable to the ordinary lateritic soil. Microstructures confirmed a highly compacted surface of mixed lateritic soil with ladle furnace slag. The ladle furnace slag is therefore one of the promising alternative low-cost materials for the soil-stabilizing application. [ABSTRACT FROM AUTHOR]