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Characteristics of the metal powder are a key factor in the success of powder bed fusion (PBF) additive manufacturing. Powders for PBF from different manufacturers may have a different particle size and/or bulk packing and flow behavior. Powder properties change as the powder is reused for multiple builds. This study seeks to measure the variability of commercial 17-4 PH stainless steel powders to determine the effect of powder variability on part density and demonstrate characterization methods that ensure part quality.

Commercial atomized metal powders from four different vendors were produced with two different atomizing gases (N2 and argon). Powder was characterized in both new and extensively reused conditions. All powders were characterized for flow and packing behavior, particle size and internal porosity. Coupons were manufactured using the laser PBF process with optimized scan strategy and exposure parameters. The quality of fabricated parts was measured using bulk density measurement.

Despite differences in powder flowability and particle size, fully dense parts (>99 per cent) were produced using all powders, except one. Residual porosity in these parts appeared to result from gas trapped in the powder particles. The powder with extensive reuse (400+ h in machine fabrication environment) exhibited reduced flowability and increased fraction of fine particles, but still produced full density parts.

This study demonstrates that full density parts can be fabricated using powders with a range of flowability and packing behavior. This suggests that a single flowability measurement may be sufficient for quality assurance in a production environment.

Adhesion has been measured between a powder injection molded (PIM) part and the stereolithography epoxy mold surrounding it after cooling. Analysis of release behavior suggests a link to the thermal properties of the mold material. Subsequent measurements of cooling in the part and at the part/mold interface are consistent with a one‐dimensional heat transfer model. Adhesion development at the part/mold interface shows a complex dependence on the thermal characteristics of both the mold and the PIM feedstock.

The purpose of this paper is to explore the work-family interface of two non-traditional forms of expatriation. The paper contributes to existing research by comparing and contrasting the experiences of international business travellers and rotational assignees, pointing out the similarities in their experiences but also showing considerable differences in how the work-family interface plays out in these two groups.

In line with the exploratory nature of the research, the authors carried out a qualitative case study drawing on interview data with rotators and international business travellers (n=20). In order to get more in-depth insights into the experiences of these two groups of assignees, the authors also used the photo-elicitation technique, which corresponds with the recent recognition that the evolving nature of international assignments requires alternative methods of inquiry to enhance the understanding of the challenges faced by them.

The study points to four major factors affecting the work-family interface: time spent away, unpredictability of work schedules, limited ability to exercise control over it as well as limited availability of organisational support. The findings illustrate that while these factors impact international business travellers and rotators alike, their intensity varies considerably in the experiences of these two groups.

The research is based on a single case study and a small sample which needs to be considered when discussing the implications of the findings. Future research can valuably extend and build on the here reported observations.

A number of practical implications are discussed, notably pertaining to the ways in which organisations can mitigate the challenges encountered by international business travellers and rotators.

The papers focuses on two groups of assignees that are underrepresented in the expatriate literature despite their increasing empirical significance in international business.

This paper seeks to present the results of an experiment to investigate the effect of six part orientation (XY, XZ, YX, YZ, ZY, ZX) and a wide range of energy densities on ultimate tensile strength (UTS) and elongation of laser‐sintered nylon 12 (PA‐12) test specimens.

ASTM Type 1 specimens were built on a DTM Sinterstation 2500+ and tensile tested on an Instron 5569 A. The resulting data were fit to non‐linear regression models based on the well‐known Weibull growth model to predict each response based on the total energy density used in each trial.

The resulting regression models provide excellent fits with low sum of squared errors and normally distributed residuals. The resulting material properties are highly affected by the energy density and the build orientation. However, once sufficient energy density is applied, properties tend to converge to consistent values. To achieve maximum UTS of approximately 52 MPa, it is recommended that values of energy density above 0.25 W‐s per mm³ be used. To achieve maximum elongation of approximately 15‐16 percent, it is recommended that values of energy density above 0.40 W‐s per mm³ be used when building parts in the XY, XZ, YX, YZ orientations. Parts built in the ZX orientation exhibit lower elongation values at or below 12 percent for even high values of energy density.

This paper extends previous work of Starr, Gornet and Usher on the relationship between material properties, part orientation and energy density by proposing the use of the Weibull growth model. Recommendations are provided to assist users in the selection of correct energy density to achieve desirable mechanical properties in each specified orientation.

Additive manufacturing technologies such as, for example, selective laser melting (SLM) offer new design possibilities for a wide range of applications and industrial sectors. Whereas many results have been published regarding material options and their static mechanical properties, the knowledge about their dynamic mechanical behaviour is still low. The purpose of this paper is to deal with the measurement of the dynamic mechanical properties of two types of stainless steels.

Specimens for dynamic testing were produced in a vertical orientation using SLM. The specimens were turned to the required end geometry and some of them were polished in order to minimise surface effects. Additionally, some samples were produced in the end geometry (“near net shape”) to investigate the effect of the comparably rough surface quality on the lifetime. The samples were tension‐tested and the results were compared to similar conventional materials.

The SLM‐fabricated stainless steels show tensile and fatigue behaviour comparable to conventionally processed materials. For SS316L the fatigue life is 25 per cent lower than conventional material, but lifetimes at higher stress amplitudes are similar. For 15‐5PH the endurance limit is 20 per cent lower than conventional material. Lifetimes at higher stress also are significantly lower for this material although the surface conditions were different for the two tests. The influence of surface quality was investigated for 316L. Polishing produced an improvement in fatigue life but lifetime behaviour at higher stress amplitudes was not significantly different compared to the behaviour of the as‐fabricated material.

In order to widen the field of applications for additive manufacturing technologies, the knowledge about the materials properties is essential, especially about the dynamic mechanical behaviour. The current study is the only published report of fatigue properties of SLM‐fabricated stainless steels.

The purpose of this study is to examine the question of whether the repatriation adjustment process varies with different combinations of duration and purpose of international assignments.

A multiple-case study within one company was conducted based on in-depth interview data.

The authors find that learning-driven international assignments are more beneficial for career growth and receive better organizational support, as assignees are able to maintain regular communication (visibility) with the home unit. On the other hand, those on demand-driven, long-duration international assignments need to have a closer connection (integration) with employees in the host unit and find it challenging to maintain high visibility in the home unit simultaneously.

The authors contribute to existing research by highlighting that demand-driven assignees on longer assignments face greater challenges upon returning home. In addition, expatriates on short-term assignments face drastically fewer challenges than expatriates on longer assignments.

Polyamide 12 (PA12) properties meet specific requirements for various applications in the automotive and aerospace industries. Bulk specimens made of PA12 and processed via the additive manufacturing technique such as selective laser sintering (SLS) present a layered structure. In case of structural applications, the fatigue performance of SLS PA12 parts is of vital importance and fatigue response studies in these type of materials are still scarce. Therefore, the purpose of this paper is to analyse the effect of the applied load orientation on the fatigue crack propagation behaviour of the layered structure of SLS PA12.

With the aim of understanding the effect of the applied load with respect to the layer orientation on the fatigue crack growth of SLS PA12, fatigue crack growth tests were carried out at two orientations. The specimens called PARA were orientated in such a way that the applied force direction belongs to the layer plane while in the group called PERP, the tensile force direction is coincident with the build direction, that is, perpendicular to the slice. Besides, special attention has been paid to the analysis of the fracture surfaces of the specimens, linking the micromechanisms of failure with the microstructure of the material.

The SLS PA12 specimens tested with the load applied parallel to the layered structure show a little better fatigue response than those tested at perpendicular orientation. The fracture surfaces of the specimens tested at perpendicular orientation are slightly smoother than those tested at parallel orientation. Crazes are the main micromechanism of failure with a crater size of 50 microns, which coincide with the spherulite size. This indicates that the void nucleation of the crazes takes places between lamellae inside the spherulites, and consequently, the craze growth and rupture occurs mainly in a transspherulitic mode.

PA12 parts manufactured via SLS are becoming more valuable in structural elements in the automative and aeronatical fields. In such applications, fatigue performance is vital for design. Fatigue studies are scarce in literature and even more when dealing with fatigue crack growth behaviour. The value of this work is the analysis of the fatigue crack growth response of these materials taking into account the anisotropic microstructure and to get a better understanding, this behaviour is explained taking into account the micromechanisms of failure and the microstructure of the material.

Projection sintering, a system for selectively sintering large areas of polymer powder simultaneously with a high-power projector is introduced. This paper aims to evaluate the suitability of laser sintering (LS) process parameters for projection sintering, as it uses substantially lower intensities, longer exposure times and larger areas than conventional LS.

The tradeoffs in sintering outcomes are evaluated by creating single layer components with varied exposure times and optical intensities. Some of these components were cross-sectioned and evaluated for degree of densification, while the single-layer thickness and the maximum tensile force was measured for the rest.

Shorter exposure times and higher intensities can create thicker and therefore stronger parts than when equal energy is applied over longer exposures. This is different from LS in which energy input (Andrew’s Number) is accepted as a reliable process variable. This difference is likely because significant thermal energy is lost from the sintering region during the exposure time – resulting in reduced peak temperatures. These thermal losses can be offset by imparting additional energy through increased exposure time or light intensity.

Most methods for evaluating LS process parameters, such as the energy melt ratio and Andrew’s Number, estimate energy input from basic process parameters. These methods do not account for thermal losses and assume that the powder absorbs all incident light. These methods become increasingly inaccurate for projection sintering with visible light where exposure times are much higher (>1s) and a larger portion of the light is reflected from the power’s surface. Understanding the appropriate sintering criteria is critical for the development of long-exposure sintering.

A new method of selectively sintering large areas is introduced that could sinter a wider variety of materials by enabling longer sintering times and may increase productivity relative to LS. This work shows that new processing parameters are required for projection sintering as traditional LS process parameters are inadequate.

Additive manufacturing (AM) of thermoplastic polymers for powder bed fusion processes typically requires each layer to be fused before the next can be deposited. The purpose of this paper is to present a volumetric AM method in the form of deeply penetrating radio frequency (RF) radiation to improve the speed of the process and the mechanical properties of the polymer parts.

The focus of this study was to demonstrate the volumetric fusion of composite mixtures containing polyamide (nylon) 12 and graphite powders using RF radiation as the sole energy source to establish the feasibility of a volumetric AM process for thermoplastic polymers. Impedance spectroscopy was used to measure the dielectric properties of the mixtures as a function of increasing graphite content and identify the percolation limit. The mixtures were then tested in a parallel plate electrode chamber connected to an RF generator to measure the heating effectiveness of different graphite concentrations. During the experiments, the surface temperature of the doped mixtures was monitored.

Nylon 12 mixtures containing between 10% and 60% graphite by weight were created, and the loss tangent reached a maximum of 35%. Selective RF heating was shown through the formation of fused composite parts within the powder beds.

The feasibility of a novel volumetric AM process for thermoplastic polymers was demonstrated in this study, in which RF radiation was used to achieve fusion in graphite-doped nylon powders.