Wire and arc additive manufacturing (WAAM) stands out from other deposition techniques for being able to produce bigger parts and with higher deposition rates. However, due to the high thermal input, it is necessary to carefully select the deposition strategy and parameters to achieve good geometry, low defects and adequate mechanical properties. As a recent technology, different studies have been developed comprehending the deposition approach, aiming to achieve parts with specific characteristics, usually evaluating the geometry, microstructure and mechanical properties, such as yield and tensile strengths, residual stresses and microhardness; however, the last is usually presented by mean values, requiring more details to comprehend its behavior further. In this sense, this work aims to evaluate the microhardness variation on walls of ER70S-6 deposited by WAAM-CMT in detail, with different deposition strategies, unidirectional and bidirectional, and with and without interlayer temperature control. The wall’s geometry was also assessed in terms of height and width. The results showed that both bidirectional deposition and temperature control contributed to improving the wall’s geometry. Combining methods led to a 26% increase in the wall width and 9% in the height; combining both methods also led to a more homogeneous distribution of microhardness throughout the wall with less than 15 HV variation. For all the deposition strategies, the wall region influenced the microhardness, and relatively higher values were obtained on the upper region of the wall, followed by the central and lower regions.

The use of cutting fluid is crucial in the grinding process due to the elevated heat generated during the process which typically flows to the workpiece and can adversely affect its integrity. Considering the conventional technique for cutting fluid application in grinding (flood), its efficiency is related to certain factors such as the type of fluid, nozzle geometry/positioning, flow rate and coolant concentration. Another parameter, one which is usually neglected, is the cutting fluid temperature. Since the heat exchange between the cutting fluid and workpiece increases with the temperature difference, controlling the cutting fluid temperature before its application could improve its cooling capability. In this context, this work aimed to analyze the surface integrity of bearing steel (hardened SAE 52100 steel) after grinding with an Al₂O₃ grinding wheel with the cutting fluid delivered via flood technique at different temperatures: 5 °C, 10 °C, 15 °C as well as room temperature (28 ± 1 °C). The surface integrity of the workpiece was analyzed in terms of surface roughness (Ra parameter), images of the ground surface, and the microhardness and microstructure beneath the machined surface. The results show that the surface roughness values reduced with the cutting fluid temperature. Furthermore, the application of a cutting fluid at low temperatures enabled the minimization of thermal damages regarding visible grinding burns, hardness variation, and microstructure changes.