Processing windows for Ti-6Al-4V fabricated by selective electron beam melting with improved beam focus and different scan line spacings

Abstract

Purpose Selective electron beam melting (SEBM) is a highly versatile powder bed fusion additive manufacturing method. SEBM is characterized by high energy densities which can be applied with nearly inertia free beam deflection at high speeds (<8.000 m/s). This paper aims to determine processing maps for Ti-6Al-4V on an Arcam Q10 machine with LaB6 cathode design. Design/methodology/approach Scan line spacings of 100, 50 and 20 µm in a broad parameter range, focusing on high deflection and build speeds are investigated. Findings There are broad processing windows for dense parts without surface flaws for all scan line spacings which are defined by the total energy input and the area melting velocity. Originality/value The differences and limitations are discussed taking into account the beam properties at high beam energy and velocity as well as evaporation related loss of alloying components.

High-Throughput Numerical Investigation of Process Parameter-Melt Pool Relationships in Electron Beam Powder Bed Fusion

“…In contrast, process parameter combinations with low line offsets had a lower line energy, and as a consequence the melt pool depth decreased significantly in the trailing melt pool regime, leading to a shift of the consolidation boundary towards higher energy inputs and lateral velocities, as shown in Figure 6a. These trends correspond well to experimentally observed trends for different line offsets [51,57]. The high beam velocity at low line offsets led to very low return times and a disproportionate increase in the cumulative heating effect with higher lateral velocities.…”

“…Figure 2 shows the calculated melt pool feature maps as a function of the area energy and lateral velocity, the derived process boundaries, and the final processing map. A variety of dependencies were observed, in accordance with previous experimental and numerical work [15,17,51]. The melt pool depth increased with a higher total energy input and constant lateral velocity and with a larger lateral velocity at a constant energy input.…”

“…The characteristic melt pool features λ n = max(λ t i ) of a parameter combination n were subsequently determined from the maximum of each quantity over each time step t i . Melt pool feature maps combined each characteristic feature for all parameter combinations and were represented as a two-dimensional slice, along the area energy E A and lateral velocity v lat axis, through the multidimensional parameter space, analog to experimental representations [51], as detailed in Figure 1e. Since the area energy E A and the lateral velocity v lat are the quantities governing the cumulative heating process underlying melt pool formation in line-based hatching strategies, this representation provided the possibility of establishing the underlying relationship between process parameters and the investigation of the influence of different processing conditions.…”

“…As detailed in Figure 2, the emerging melt pool geometries exhibited fundamental patterns. A higher lateral velocity decreased the return time and time for heat dissipation; therefore, the magnitude of the cumulative heating effect increased and the melt pool size increased, shifting the necessary energy for consolidation towards a lower energy [15,51,52]. A higher energy input directly affected the melt pool depth but also increased the energy deposited at previous hatch lines and, therefore, the magnitude of the cumulative heating effect.…”

Process Window for Electron Beam Melting of 316LN Stainless Steel

“…The dominant EBM machine supplier for industrial applications, Arcam (Arcam AB, Gothenburg, Sweden), currently supports six different materials, while the numerous suppliers of laser-based equipment offer more than 20 different materials. EBM process windows for pure copper [1][2][3], Inconel 718 [4], and Ti64 [5,6] have previously been reported. Wang et al [7] presented work on EBM process development for 316L, and other researchers [8][9][10][11] have also presented work on EBM of 316LN, which is a nitrogen-enriched version of 316L, although without disclosing their process development methods.…”