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In-situ X-ray diffraction experiments were performed during Laser Metal Deposition of steel X40CrMoV5-1 at the Deutsches Elektronen-Synchrotron (DESY). The measurements were performed with monochromatic high-energy X-ray radiation in transmission, while full diffraction rings were recorded at 10 Hz. The first generated layer is remelted until deposition of the third layer on top, while partial re-austenitizing of the first layer occurs until deposition of the 7 th layer. Selftempering effects were analyzed based on martensite tetragonality. Strong decrease of carbon content in solution in martensite occurs during the deposition of the first five layers, resulting in low local hardness.

A manifold variety of additive manufacturing techniques has a significant positive impact on many industry sectors. Large components are often manufactured via directed energy deposition (DED) instead of using powder bed fusion processes (PBF). The advantages of the DED process are a high build-up rate with values up to 300 cm3/h and a nearly limitless build-up volume. In combination with the lightweight material aluminum it is possible to manufacture large lightweight components with geometries adapted to customer requirements in small batches. This contributes the pursuit of higher efficiency of machines through lightweight materials as well as lightweight design. A low-defect additive manufacturing of high strength aluminum EN AW-7075 powder via DED is an important challenge. The laser power has a significant influence on the remaining porosity. By increasing the laser power from 2 kW to 4 kW the porosity in single welding tracks can be lowered from 2.1% to only (0.09 ± 0.07)% (n = 3). However, when manufacturing larger specimens; the remaining porosity is higher than in single tracks; which can be attributed to the oxide skin on the preceding welding tracks. Further investigations regarding the mechanical properties were carried out. In tensile tests an ultimate tensile strength of (222 ± 17) MPa (n = 6) was measured. The DED processed EN AW-7075 shows comparable mechanical properties to PBF processed EN AW-7075.

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